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2014-01-13sched/clock, x86: Use a static_key for sched_clock_stablePeter Zijlstra
In order to avoid the runtime condition and variable load turn sched_clock_stable into a static_key. Also provide a shorter implementation of local_clock() and cpu_clock(int) when sched_clock_stable==1. MAINLINE PRE POST sched_clock_stable: 1 1 1 (cold) sched_clock: 329841 221876 215295 (cold) local_clock: 301773 234692 220773 (warm) sched_clock: 38375 25602 25659 (warm) local_clock: 100371 33265 27242 (warm) rdtsc: 27340 24214 24208 sched_clock_stable: 0 0 0 (cold) sched_clock: 382634 235941 237019 (cold) local_clock: 396890 297017 294819 (warm) sched_clock: 38194 25233 25609 (warm) local_clock: 143452 71234 71232 (warm) rdtsc: 27345 24245 24243 Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-eummbdechzz37mwmpags1gjr@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-07-18tracing: Typo fix on ring buffer commentszhangwei(Jovi)
There have some mismatch between comments with real function name, update it. This patch also add some missed function arguments description. Link: http://lkml.kernel.org/r/51E3B3B2.4080307@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-18tracing: Use trace_seq_puts()/trace_seq_putc() where possiblezhangwei(Jovi)
For string without format specifiers, use trace_seq_puts() or trace_seq_putc(). Link: http://lkml.kernel.org/r/51E3B3AC.1000605@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> [ fixed a trace_seq_putc(s, " ") to trace_seq_putc(s, ' ') ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-05-28ring-buffer: Do not poll non allocated cpu buffersSteven Rostedt (Red Hat)
The tracing infrastructure sets up for possible CPUs, but it uses the ring buffer polling, it is possible to call the ring buffer polling code with a CPU that hasn't been allocated. This will cause a kernel oops when it access a ring buffer cpu buffer that is part of the possible cpus but hasn't been allocated yet as the CPU has never been online. Reported-by: Mauro Carvalho Chehab <mchehab@redhat.com> Tested-by: Mauro Carvalho Chehab <mchehab@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-04-29Merge tag 'trace-3.10' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "Along with the usual minor fixes and clean ups there are a few major changes with this pull request. 1) Multiple buffers for the ftrace facility This feature has been requested by many people over the last few years. I even heard that Google was about to implement it themselves. I finally had time and cleaned up the code such that you can now create multiple instances of the ftrace buffer and have different events go to different buffers. This way, a low frequency event will not be lost in the noise of a high frequency event. Note, currently only events can go to different buffers, the tracers (ie function, function_graph and the latency tracers) still can only be written to the main buffer. 2) The function tracer triggers have now been extended. The function tracer had two triggers. One to enable tracing when a function is hit, and one to disable tracing. Now you can record a stack trace on a single (or many) function(s), take a snapshot of the buffer (copy it to the snapshot buffer), and you can enable or disable an event to be traced when a function is hit. 3) A perf clock has been added. A "perf" clock can be chosen to be used when tracing. This will cause ftrace to use the same clock as perf uses, and hopefully this will make it easier to interleave the perf and ftrace data for analysis." * tag 'trace-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (82 commits) tracepoints: Prevent null probe from being added tracing: Compare to 1 instead of zero for is_signed_type() tracing: Remove obsolete macro guard _TRACE_PROFILE_INIT ftrace: Get rid of ftrace_profile_bits tracing: Check return value of tracing_init_dentry() tracing: Get rid of unneeded key calculation in ftrace_hash_move() tracing: Reset ftrace_graph_filter_enabled if count is zero tracing: Fix off-by-one on allocating stat->pages kernel: tracing: Use strlcpy instead of strncpy tracing: Update debugfs README file tracing: Fix ftrace_dump() tracing: Rename trace_event_mutex to trace_event_sem tracing: Fix comment about prefix in arch_syscall_match_sym_name() tracing: Convert trace_destroy_fields() to static tracing: Move find_event_field() into trace_events.c tracing: Use TRACE_MAX_PRINT instead of constant tracing: Use pr_warn_once instead of open coded implementation ring-buffer: Add ring buffer startup selftest tracing: Bring Documentation/trace/ftrace.txt up to date tracing: Add "perf" trace_clock ... Conflicts: kernel/trace/ftrace.c kernel/trace/trace.c
2013-03-15ring-buffer: Add ring buffer startup selftestSteven Rostedt (Red Hat)
When testing my large changes to the ftrace system, there was a bug that looked like the ring buffer was dropping events. I wrote up a quick integrity checker of the ring buffer to see if it was. Although the bug ended up being something stupid I did in ftrace, and had nothing to do with the ring buffer, I figured if I spent the time to write up this test, I might as well include it in the kernel. I cleaned it up a bit, as the original version was rather ugly. Not saying this version is pretty, but it's a beauty queen compared to what I original wrote. To enable the start up test, set CONFIG_RING_BUFFER_STARTUP_TEST. Note, it runs for 10 seconds, so it will slow your boot time by at least 10 more seconds. What it does is documented in both the comments and the Kconfig help. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-03-15ring-buffer: Do not use schedule_work_on() for current CPUSteven Rostedt (Red Hat)
The ring buffer updates when done while the ring buffer is active, needs to be completed on the CPU that is used for the ring buffer per_cpu buffer. To accomplish this, schedule_work_on() is used to schedule work on the given CPU. Now there's no reason to use schedule_work_on() if the process doing the update happens to be on the CPU that it is processing. It has already filled the requirement. Instead, just do the work and continue. This is needed for tracing_snapshot_alloc() where it may be called really early in boot, where the work queues have not been set up yet. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-03-15ring-buffer: Init waitqueue for blocked readersSteven Rostedt (Red Hat)
The move of blocked readers to the ring buffer left out the init of the wait queue that is used. Tests missed this due to running stress tests against the buffers, which didn't allow for any readers to end up waiting. Running a simple read and wait triggered a bug. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-03-15tracing/ring-buffer: Move poll wake ups into ring buffer codeSteven Rostedt (Red Hat)
Move the logic to wake up on ring buffer data into the ring buffer code itself. This simplifies the tracing code a lot and also has the added benefit that waiters on one of the instance buffers can be woken only when data is added to that instance instead of data added to any instance. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-03-03Merge tag 'metag-v3.9-rc1-v4' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag Pull new ImgTec Meta architecture from James Hogan: "This adds core architecture support for Imagination's Meta processor cores, followed by some later miscellaneous arch/metag cleanups and fixes which I kept separate to ease review: - Support for basic Meta 1 (ATP) and Meta 2 (HTP) core architecture - A few fixes all over, particularly for symbol prefixes - A few privilege protection fixes - Several cleanups (setup.c includes, split out a lot of metag_ksyms.c) - Fix some missing exports - Convert hugetlb to use vm_unmapped_area() - Copy device tree to non-init memory - Provide dma_get_sgtable()" * tag 'metag-v3.9-rc1-v4' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag: (61 commits) metag: Provide dma_get_sgtable() metag: prom.h: remove declaration of metag_dt_memblock_reserve() metag: copy devicetree to non-init memory metag: cleanup metag_ksyms.c includes metag: move mm/init.c exports out of metag_ksyms.c metag: move usercopy.c exports out of metag_ksyms.c metag: move setup.c exports out of metag_ksyms.c metag: move kick.c exports out of metag_ksyms.c metag: move traps.c exports out of metag_ksyms.c metag: move irq enable out of irqflags.h on SMP genksyms: fix metag symbol prefix on crc symbols metag: hugetlb: convert to vm_unmapped_area() metag: export clear_page and copy_page metag: export metag_code_cache_flush_all metag: protect more non-MMU memory regions metag: make TXPRIVEXT bits explicit metag: kernel/setup.c: sort includes perf: Enable building perf tools for Meta metag: add boot time LNKGET/LNKSET check metag: add __init to metag_cache_probe() ...
2013-03-02trace/ring_buffer: handle 64bit aligned structsJames Hogan
Some 32 bit architectures require 64 bit values to be aligned (for example Meta which has 64 bit read/write instructions). These require 8 byte alignment of event data too, so use !CONFIG_HAVE_64BIT_ALIGNED_ACCESS instead of !CONFIG_64BIT || CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS to decide alignment, and align buffer_data_page::data accordingly. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> (previous version subtly different)
2013-01-30ring-buffer: Add stats field for amount read from trace ring bufferSteven Rostedt (Red Hat)
Add a stat about the number of events read from the ring buffer: # cat /debug/tracing/per_cpu/cpu0/stats entries: 39869 overrun: 870512 commit overrun: 0 bytes: 1449912 oldest event ts: 6561.368690 now ts: 6565.246426 dropped events: 0 read events: 112 <-- Added Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-01-22ring-buffer: Remove trace.h from ring_buffer.cSteven Rostedt
ring_buffer.c use to require declarations from trace.h, but these have moved to the generic header files. There's nothing in trace.h that ring_buffer.c requires. There's some headers that trace.h included that ring_buffer.c needs, but it's best that it includes them directly, and not include trace.h. Also, some things may use ring_buffer.c without having tracing configured. This removes the dependency that may come in the future. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-01-22ring-buffer: User context bit recursion checkingSteven Rostedt
Using context bit recursion checking, we can help increase the performance of the ring buffer. Before this patch: # echo function > /debug/tracing/current_tracer # for i in `seq 10`; do ./hackbench 50; done Time: 10.285 Time: 10.407 Time: 10.243 Time: 10.372 Time: 10.380 Time: 10.198 Time: 10.272 Time: 10.354 Time: 10.248 Time: 10.253 (average: 10.3012) Now we have: # echo function > /debug/tracing/current_tracer # for i in `seq 10`; do ./hackbench 50; done Time: 9.712 Time: 9.824 Time: 9.861 Time: 9.827 Time: 9.962 Time: 9.905 Time: 9.886 Time: 10.088 Time: 9.861 Time: 9.834 (average: 9.876) a 4% savings! Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-01-21ring-buffer: Remove unnecessary recusive call in rb_advance_iter()Steven Rostedt
The original ring-buffer code had special checks at the start of rb_advance_iter() and instead of repeating them again at the end of the function if a certain condition existed, I just did a recursive call to rb_advance_iter() because the special condition would cause rb_advance_iter() to return early (after the checks). But as things have changed, the special checks no longer exist and the only thing done for the special_condition is to call rb_inc_iter() and return. Instead of doing a confusing recursive call, just call rb_inc_iter instead. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-12-11Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Ingo Molnar: "These are late-v3.7 pending fixes for tracing." Fix up trivial conflict in kernel/trace/ring_buffer.c: the NULL pointer fix clashed with the change of type of the 'ret' variable. * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: ring-buffer: Fix race between integrity check and readers ring-buffer: Fix NULL pointer if rb_set_head_page() fails ftrace: Clear bits properly in reset_iter_read()
2012-11-30ring-buffer: Fix race between integrity check and readersSteven Rostedt
The function rb_check_pages() was added to make sure the ring buffer's pages were sane. This check is done when the ring buffer size is modified as well as when the iterator is released (closing the "trace" file), as that was considered a non fast path and a good place to do a sanity check. The problem is that the check does not have any locks around it. If one process were to read the trace file, and another were to read the raw binary file, the check could happen while the reader is reading the file. The issues with this is that the check requires to clear the HEAD page before doing the full check and it restores it afterward. But readers require the HEAD page to exist before it can read the buffer, otherwise it gives a nasty warning and disables the buffer. By adding the reader lock around the check, this keeps the race from happening. Cc: stable@vger.kernel.org # 3.6 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-30ring-buffer: Fix NULL pointer if rb_set_head_page() failsSteven Rostedt
The function rb_set_head_page() searches the list of ring buffer pages for a the page that has the HEAD page flag set. If it does not find it, it will do a WARN_ON(), disable the ring buffer and return NULL, as this should never happen. But if this bug happens to happen, not all callers of this function can handle a NULL pointer being returned from it. That needs to be fixed. Cc: stable@vger.kernel.org # 3.0+ Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-11-02ring-buffer: Change unsigned long type of ring_buffer_oldest_event_ts() to u64Yoshihiro YUNOMAE
ring_buffer_oldest_event_ts() should return a value of u64 type, because ring_buffer_per_cpu->buffer_page->buffer_data_page->time_stamp is u64 type. Link: http://lkml.kernel.org/r/1349998076-15495-5-git-send-email-dhsharp@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> Signed-off-by: David Sharp <dhsharp@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-10-31tracing: Trivial cleanupDavid Sharp
Remove ftrace_format_syscall() declaration; it is neither defined nor used. Also update a comment and formatting. Link: http://lkml.kernel.org/r/1339112785-21806-1-git-send-email-vnagarnaik@google.com Signed-off-by: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-10-31ring-buffer: Add a 'dropped events' counterSlava Pestov
The existing 'overrun' counter is incremented when the ring buffer wraps around, with overflow on (the default). We wanted a way to count requests lost from the buffer filling up with overflow off, too. I decided to add a new counter instead of retro-fitting the existing one because it seems like a different statistic to count conceptually, and also because of how the code was structured. Link: http://lkml.kernel.org/r/1310765038-26399-1-git-send-email-slavapestov@google.com Signed-off-by: Slava Pestov <slavapestov@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-10-11ring-buffer: Check for uninitialized cpu buffer before resizingVaibhav Nagarnaik
With a system where, num_present_cpus < num_possible_cpus, even if all CPUs are online, non-present CPUs don't have per_cpu buffers allocated. If per_cpu/<cpu>/buffer_size_kb is modified for such a CPU, it can cause a panic due to NULL dereference in ring_buffer_resize(). To fix this, resize operation is allowed only if the per-cpu buffer has been initialized. Link: http://lkml.kernel.org/r/1349912427-6486-1-git-send-email-vnagarnaik@google.com Cc: stable@vger.kernel.org # 3.5+ Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-08-07tracing/trivial: Fix some typos in kernel/traceWang Tianhong
Fix some typos in kernel/trace. Link: http://lkml.kernel.org/r/1343887320.2228.9.camel@louis-ThinkPad-T410 Signed-off-by: Wang Tianhong <wangthbj@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-07-18Merge branch 'linus' into perf/coreIngo Molnar
Pick up the latest ring-buffer fixes, before applying a new fix. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-06-29ring-buffer: Fix accounting of entries when removing pagesVaibhav Nagarnaik
When removing pages from the ring buffer, its state is not reset. This means that the counters need to be correctly updated to account for the pages removed. Update the overrun counter to reflect the removed events from the pages. Link: http://lkml.kernel.org/r/1340998301-1715-1-git-send-email-vnagarnaik@google.com Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-06-29ring-buffer: Fix crash due to uninitialized new_pages list headVaibhav Nagarnaik
The new_pages list head in the cpu_buffer is not initialized. When adding pages to the ring buffer, if the memory allocation fails in ring_buffer_resize, the clean up handler tries to free up the allocated pages from all the cpu buffers. The panic is caused by referencing the uninitialized new_pages list head. Initializing the new_pages list head in rb_allocate_cpu_buffer fixes this. Link: http://lkml.kernel.org/r/1340391005-10880-1-git-send-email-vnagarnaik@google.com Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-06-28ring-buffer: Fix uninitialized read_stampSteven Rostedt
The ring buffer reader page is used to swap a page from the writable ring buffer. If the writer happens to be on that page, it ends up on the reader page, but will simply move off of it, back into the writable ring buffer as writes are added. The time stamp passed back to the readers is stored in the cpu_buffer per CPU descriptor. This stamp is updated when a swap of the reader page takes place, and it reads the current stamp from the page taken from the writable ring buffer. Everytime a writer goes to a new page, it updates the time stamp of that page. The problem happens if a reader reads a page from an empty per CPU ring buffer. If the buffer is empty, the swap still takes place, placing the writer at the start of the reader page. If at a later time, a write happens, it updates the page's time stamp and continues. But the problem is that the read_stamp does not get updated, because the page was already swapped. The solution to this was to not swap the page if the ring buffer happens to be empty. This also removes the side effect that the writes on the reader page will not get updated because the writer never gets back on the reader page without a swap. That is, if a read happens on an empty buffer, but then no reads happen for a while. If a swap took place, and the writer were to start writing a lot of data (function tracer), it will start overflowing the ring buffer and overwrite the older data. But because the writer never goes back onto the reader page, the data left on the reader page never gets overwritten. This causes the reader to see really old data, followed by a jump to newer data. Link: http://lkml.kernel.org/r/1340060577-9112-1-git-send-email-dhsharp@google.com Google-Bug-Id: 6410455 Reported-by: David Sharp <dhsharp@google.com> tested-by: David Sharp <dhsharp@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-05-23ring-buffer: Check for valid buffer before changing sizeSteven Rostedt
On some machines the number of possible CPUS is not the same as the number of CPUs that is on the machine. Ftrace uses possible_cpus to update the tracing structures but the ring buffer only allocates per cpu buffers for online CPUs when they come up. When the wakeup tracer was enabled in such a case, the ftrace code enabled all possible cpu buffers, but the code in ring_buffer_resize() did not check to see if the buffer in question was allocated. Since boot up CPUs did not match possible CPUs it caused the following crash: BUG: unable to handle kernel NULL pointer dereference at 00000020 IP: [<c1097851>] ring_buffer_resize+0x16a/0x28d *pde = 00000000 Oops: 0000 [#1] PREEMPT SMP Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: [last unloaded: scsi_wait_scan] Pid: 1387, comm: bash Not tainted 3.4.0-test+ #13 /DG965MQ EIP: 0060:[<c1097851>] EFLAGS: 00010217 CPU: 0 EIP is at ring_buffer_resize+0x16a/0x28d EAX: f5a14340 EBX: f6026b80 ECX: 00000ff4 EDX: 00000ff3 ESI: 00000000 EDI: 00000002 EBP: f4275ecc ESP: f4275eb0 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 CR0: 80050033 CR2: 00000020 CR3: 34396000 CR4: 000007d0 DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 DR6: ffff0ff0 DR7: 00000400 Process bash (pid: 1387, ti=f4274000 task=f4380cb0 task.ti=f4274000) Stack: c109cf9a f6026b98 00000162 00160f68 00000006 00160f68 00000002 f4275ef0 c109d013 f4275ee8 c123b72a c1c0bf00 c1cc81dc 00000005 f4275f98 00000007 f4275f70 c109d0c7 7700000e 75656b61 00000070 f5e90900 f5c4e198 00000301 Call Trace: [<c109cf9a>] ? tracing_set_tracer+0x115/0x1e9 [<c109d013>] tracing_set_tracer+0x18e/0x1e9 [<c123b72a>] ? _copy_from_user+0x30/0x46 [<c109d0c7>] tracing_set_trace_write+0x59/0x7f [<c10ec01e>] ? fput+0x18/0x1c6 [<c11f8732>] ? security_file_permission+0x27/0x2b [<c10eaacd>] ? rw_verify_area+0xcf/0xf2 [<c10ec01e>] ? fput+0x18/0x1c6 [<c109d06e>] ? tracing_set_tracer+0x1e9/0x1e9 [<c10ead77>] vfs_write+0x8b/0xe3 [<c10ebead>] ? fget_light+0x30/0x81 [<c10eaf54>] sys_write+0x42/0x63 [<c1834fbf>] sysenter_do_call+0x12/0x28 This happens with the latency tracer as the ftrace code updates the saved max buffer via its cpumask and not with a global setting. Adding a check in ring_buffer_resize() to make sure the buffer being resized exists, fixes the problem. Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-05-19ring-buffer: Merge separate resize loopsVaibhav Nagarnaik
There are 2 separate loops to resize cpu buffers that are online and offline. Merge them to make the code look better. Also change the name from update_completion to update_done to allow shorter lines. Link: http://lkml.kernel.org/r/1337372991-14783-1-git-send-email-vnagarnaik@google.com Cc: Laurent Chavey <chavey@google.com> Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-05-16ring-buffer: Reset head page before running self testSteven Rostedt
When the ring buffer does its consistency test on itself, it removes the head page, runs the tests, and then adds it back to what the "head_page" pointer was. But because the head_page pointer may lack behind the real head page (held by the link list pointer). The reset may be incorrect. Instead, if the head_page exists (it does not on first allocation) reset it back to the real head page before running the consistency tests. Then it will be put back to its original location after the tests are complete. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-05-16ring-buffer: Add integrity check at end of iter readSteven Rostedt
There use to be ring buffer integrity checks after updating the size of the ring buffer. But now that the ring buffer can modify the size while the system is running, the integrity checks were removed, as they require the ring buffer to be disabed to perform the check. Move the integrity check to the reading of the ring buffer via the iterator reads (the "trace" file). As reading via an iterator requires disabling the ring buffer, it is a perfect place to have it. If the ring buffer happens to be disabled when updating the size, we still perform the integrity check. Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-05-16ring-buffer: Make addition of pages in ring buffer atomicVaibhav Nagarnaik
This patch adds the capability to add new pages to a ring buffer atomically while write operations are going on. This makes it possible to expand the ring buffer size without reinitializing the ring buffer. The new pages are attached between the head page and its previous page. Link: http://lkml.kernel.org/r/1336096792-25373-2-git-send-email-vnagarnaik@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Laurent Chavey <chavey@google.com> Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-05-16ring-buffer: Make removal of ring buffer pages atomicVaibhav Nagarnaik
This patch adds the capability to remove pages from a ring buffer without destroying any existing data in it. This is done by removing the pages after the tail page. This makes sure that first all the empty pages in the ring buffer are removed. If the head page is one in the list of pages to be removed, then the page after the removed ones is made the head page. This removes the oldest data from the ring buffer and keeps the latest data around to be read. To do this in a non-racey manner, tracing is stopped for a very short time while the pages to be removed are identified and unlinked from the ring buffer. The pages are freed after the tracing is restarted to minimize the time needed to stop tracing. The context in which the pages from the per-cpu ring buffer are removed runs on the respective CPU. This minimizes the events not traced to only NMI trace contexts. Link: http://lkml.kernel.org/r/1336096792-25373-1-git-send-email-vnagarnaik@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Laurent Chavey <chavey@google.com> Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-04-23ring-buffer: Add per_cpu ring buffer control filesVaibhav Nagarnaik
Add a debugfs entry under per_cpu/ folder for each cpu called buffer_size_kb to control the ring buffer size for each CPU independently. If the global file buffer_size_kb is used to set size, the individual ring buffers will be adjusted to the given size. The buffer_size_kb will report the common size to maintain backward compatibility. If the buffer_size_kb file under the per_cpu/ directory is used to change buffer size for a specific CPU, only the size of the respective ring buffer is updated. When tracing/buffer_size_kb is read, it reports 'X' to indicate that sizes of per_cpu ring buffers are not equivalent. Link: http://lkml.kernel.org/r/1328212844-11889-1-git-send-email-vnagarnaik@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Michael Rubin <mrubin@google.com> Cc: David Sharp <dhsharp@google.com> Cc: Justin Teravest <teravest@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-02-22tracing/ring-buffer: Only have tracing_on disable tracing buffersSteven Rostedt
As the ring-buffer code is being used by other facilities in the kernel, having tracing_on file disable *all* buffers is not a desired affect. It should only disable the ftrace buffers that are being used. Move the code into the trace.c file and use the buffer disabling for tracing_on() and tracing_off(). This way only the ftrace buffers will be affected by them and other kernel utilities will not be confused to why their output suddenly stopped. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-10-26Merge branch 'perf-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (121 commits) perf symbols: Increase symbol KSYM_NAME_LEN size perf hists browser: Refuse 'a' hotkey on non symbolic views perf ui browser: Use libslang to read keys perf tools: Fix tracing info recording perf hists browser: Elide DSO column when it is set to just one DSO, ditto for threads perf hists: Don't consider filtered entries when calculating column widths perf hists: Don't decay total_period for filtered entries perf hists browser: Honour symbol_conf.show_{nr_samples,total_period} perf hists browser: Do not exit on tab key with single event perf annotate browser: Don't change selection line when returning from callq perf tools: handle endianness of feature bitmap perf tools: Add prelink suggestion to dso update message perf script: Fix unknown feature comment perf hists browser: Apply the dso and thread filters when merging new batches perf hists: Move the dso and thread filters from hist_browser perf ui browser: Honour the xterm colors perf top tui: Give color hints just on the percentage, like on --stdio perf ui browser: Make the colors configurable and change the defaults perf tui: Remove unneeded call to newtCls on startup perf hists: Don't format the percentage on hist_entry__snprintf ... Fix up conflicts in arch/x86/kernel/kprobes.c manually. Ingo's tree did the insane "add volatile to const array", which just doesn't make sense ("volatile const"?). But we could remove the const *and* make the array volatile to make doubly sure that gcc doesn't optimize it away.. Also fix up kernel/trace/ring_buffer.c non-data-conflicts manually: the reader_lock has been turned into a raw lock by the core locking merge, and there was a new user of it introduced in this perf core merge. Make sure that new use also uses the raw accessor functions.
2011-09-13locking, tracing: Annotate tracing locks as rawThomas Gleixner
The tracing locks can be taken in atomic context and therefore cannot be preempted on -rt - annotate it. In mainline this change documents the low level nature of the lock - otherwise there's no functional difference. Lockdep and Sparse checking will work as usual. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-30trace: Add ring buffer stats to measure rate of eventsVaibhav Nagarnaik
The stats file under per_cpu folder provides the number of entries, overruns and other statistics about the CPU ring buffer. However, the numbers do not provide any indication of how full the ring buffer is in bytes compared to the overall size in bytes. Also, it is helpful to know the rate at which the cpu buffer is filling up. This patch adds an entry "bytes: " in printed stats for per_cpu ring buffer which provides the actual bytes consumed in the ring buffer. This field includes the number of bytes used by recorded events and the padding bytes added when moving the tail pointer to next page. It also adds the following time stamps: "oldest event ts:" - the oldest timestamp in the ring buffer "now ts:" - the timestamp at the time of reading The field "now ts" provides a consistent time snapshot to the userspace when being read. This is read from the same trace clock used by tracing event timestamps. Together, these values provide the rate at which the buffer is filling up, from the formula: bytes / (now_ts - oldest_event_ts) Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: Michael Rubin <mrubin@google.com> Cc: David Sharp <dhsharp@google.com> Link: http://lkml.kernel.org/r/1313531179-9323-3-git-send-email-vnagarnaik@google.com Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-06-14ring-buffer: Set __GFP_NORETRY flag for ring buffer allocating processVaibhav Nagarnaik
The tracing ring buffer is allocated from kernel memory. While allocating a large chunk of memory, OOM might happen which destabilizes the system. Thus random processes might get killed during the allocation. This patch adds __GFP_NORETRY flag to the ring buffer allocation calls to make it fail more gracefully if the system will not be able to complete the allocation request. Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Michael Rubin <mrubin@google.com> Cc: David Sharp <dhsharp@google.com> Link: http://lkml.kernel.org/r/1307491302-9236-1-git-send-email-vnagarnaik@google.com Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-06-14tracing: Convert to kstrtoul_from_userPeter Huewe
This patch replaces the code for getting an unsigned long from a userspace buffer by a simple call to kstroul_from_user. This makes it easier to read and less error prone. Signed-off-by: Peter Huewe <peterhuewe@gmx.de> Link: http://lkml.kernel.org/r/1307476707-14762-1-git-send-email-peterhuewe@gmx.de Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-06-14tracing: Use NUMA allocation for per-cpu ring buffer pagesVaibhav Nagarnaik
The tracing ring buffer is a group of per-cpu ring buffers where allocation and logging is done on a per-cpu basis. The events that are generated on a particular CPU are logged in the corresponding buffer. This is to provide wait-free writes between CPUs and good NUMA node locality while accessing the ring buffer. However, the allocation routines consider NUMA locality only for buffer page metadata and not for the actual buffer page. This causes the pages to be allocated on the NUMA node local to the CPU where the allocation routine is running at the time. This patch fixes the problem by using a NUMA node specific allocation routine so that the pages are allocated from a NUMA node local to the logging CPU. I tested with the getuid_microbench from autotest. It is a simple binary that calls getuid() in a loop and measures the average time for the syscall to complete. The following command was used to test: $ getuid_microbench 1000000 Compared the numbers found on kernel with and without this patch and found that logging latency decreases by 30-50 ns/call. tracing with non-NUMA allocation - 569 ns/call tracing with NUMA allocation - 512 ns/call Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Michael Rubin <mrubin@google.com> Cc: David Sharp <dhsharp@google.com> Link: http://lkml.kernel.org/r/1304470602-20366-1-git-send-email-vnagarnaik@google.com Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-25ftrace: Add internal recursive checksSteven Rostedt
Witold reported a reboot caused by the selftests of the dynamic function tracer. He sent me a config and I used ktest to do a config_bisect on it (as my config did not cause the crash). It pointed out that the problem config was CONFIG_PROVE_RCU. What happened was that if multiple callbacks are attached to the function tracer, we iterate a list of callbacks. Because the list is managed by synchronize_sched() and preempt_disable, the access to the pointers uses rcu_dereference_raw(). When PROVE_RCU is enabled, the rcu_dereference_raw() calls some debugging functions, which happen to be traced. The tracing of the debug function would then call rcu_dereference_raw() which would then call the debug function and then... well you get the idea. I first wrote two different patches to solve this bug. 1) add a __rcu_dereference_raw() that would not do any checks. 2) add notrace to the offending debug functions. Both of these patches worked. Talking with Paul McKenney on IRC, he suggested to add recursion detection instead. This seemed to be a better solution, so I decided to implement it. As the task_struct already has a trace_recursion to detect recursion in the ring buffer, and that has a very small number it allows, I decided to use that same variable to add flags that can detect the recursion inside the infrastructure of the function tracer. I plan to change it so that the task struct bit can be checked in mcount, but as that requires changes to all archs, I will hold that off to the next merge window. Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1306348063.1465.116.camel@gandalf.stny.rr.com Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-03-31Fix common misspellingsLucas De Marchi
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-18Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (47 commits) doc: CONFIG_UNEVICTABLE_LRU doesn't exist anymore Update cpuset info & webiste for cgroups dcdbas: force SMI to happen when expected arch/arm/Kconfig: remove one to many l's in the word. asm-generic/user.h: Fix spelling in comment drm: fix printk typo 'sracth' Remove one to many n's in a word Documentation/filesystems/romfs.txt: fixing link to genromfs drivers:scsi Change printk typo initate -> initiate serial, pch uart: Remove duplicate inclusion of linux/pci.h header fs/eventpoll.c: fix spelling mm: Fix out-of-date comments which refers non-existent functions drm: Fix printk typo 'failled' coh901318.c: Change initate to initiate. mbox-db5500.c Change initate to initiate. edac: correct i82975x error-info reported edac: correct i82975x mci initialisation edac: correct commented info fs: update comments to point correct document target: remove duplicate include of target/target_core_device.h from drivers/target/target_core_hba.c ... Trivial conflict in fs/eventpoll.c (spelling vs addition)
2011-03-10tracing: Explain about unstable clock on resume with ring buffer warningJiri Olsa
The "Delta way too big" warning might appear on a system with a unstable shed clock right after the system is resumed and tracing was enabled at time of suspend. Since it's not realy a bug, and the unstable sched clock is working fast and reliable otherwise, Steven suggested to keep using the sched clock in any case and just to make note in the warning itself. v2 changes: - added #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK Signed-off-by: Jiri Olsa <jolsa@redhat.com> LKML-Reference: <20110218145219.GD2604@jolsa.brq.redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-03-09ring-buffer: Remove unused #include <linux/trace_irq.h>David Sharp
Signed-off-by: David Sharp <dhsharp@google.com> LKML-Reference: <1291421609-14665-3-git-send-email-dhsharp@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-03-09tracing: Add an 'overwrite' trace_option.David Sharp
Add an "overwrite" trace_option for ftrace to control whether the buffer should be overwritten on overflow or not. The default remains to overwrite old events when the buffer is full. This patch adds the option to instead discard newest events when the buffer is full. This is useful to get a snapshot of traces just after enabling traces. Dropping the current event is also a simpler code path. Signed-off-by: David Sharp <dhsharp@google.com> LKML-Reference: <1291844807-15481-1-git-send-email-dhsharp@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-02-18Revert "tracing: Add unstable sched clock note to the warning"Ingo Molnar
This reverts commit 5e38ca8f3ea423442eaafe1b7e206084aa38120a. Breaks the build of several !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK architectures. Cc: Jiri Olsa <jolsa@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Message-ID: <20110217171823.GB17058@elte.hu> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-02-08tracing: Add unstable sched clock note to the warningJiri Olsa
The warning "Delta way too big" warning might appear on a system with unstable shed clock right after the system is resumed and tracing was enabled during the suspend. Since it's not realy bug, and the unstable sched clock is working fast and reliable otherwise, Steven suggested to keep using the sched clock in any case and just to make note in the warning itself. Signed-off-by: Jiri Olsa <jolsa@redhat.com> LKML-Reference: <1296649698-6003-1-git-send-email-jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-01-19Kill off warning: ‘inline’ is not at beginning of declarationJesper Juhl
Fix a bunch of warning: ‘inline’ is not at beginning of declaration messages when building a 'make allyesconfig' kernel with -Wextra. These warnings are trivial to kill, yet rather annoying when building with -Wextra. The more we can cut down on pointless crap like this the better (IMHO). A previous patch to do this for a 'allnoconfig' build has already been merged. This just takes the cleanup a little further. Signed-off-by: Jesper Juhl <jj@chaosbits.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>