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2018-08-21blk-mq: init hctx sched after update ctx and hctx mappingJianchao Wang
Currently, when update nr_hw_queues, IO scheduler's init_hctx will be invoked before the mapping between ctx and hctx is adapted correctly by blk_mq_map_swqueue. The IO scheduler init_hctx (kyber) may depend on this mapping and get wrong result and panic finally. A simply way to fix this is that switch the IO scheduler to 'none' before update the nr_hw_queues, and then switch it back after update nr_hw_queues. blk_mq_sched_init_/exit_hctx are removed due to nobody use them any more. Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-01block: move sysfs_lock into elevator_initChristoph Hellwig
Both callers take just around so function call, so move it in. Also remove the now pointless blk_mq_sched_init wrapper. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Tested-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-17blk-mq-sched: remove unused 'can_block' arg from blk_mq_sched_insert_requestMike Snitzer
After commit: 923218f6166a ("blk-mq: don't allocate driver tag upfront for flush rq") we no longer use the 'can_block' argument in blk_mq_sched_insert_request(). Kill it. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Added actual commit message as to why it's being removed. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-22Merge commit '8e8320c9315c' into for-4.13/blockJens Axboe
Pull in the fix for shared tags, as it conflicts with the pending changes in for-4.13/block. We already pulled in v4.12-rc5 to solve other conflicts or get fixes that went into 4.12, so not a lot of changes in this merge. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-21blk-mq: fix performance regression with shared tagsJens Axboe
If we have shared tags enabled, then every IO completion will trigger a full loop of every queue belonging to a tag set, and every hardware queue for each of those queues, even if nothing needs to be done. This causes a massive performance regression if you have a lot of shared devices. Instead of doing this huge full scan on every IO, add an atomic counter to the main queue that tracks how many hardware queues have been marked as needing a restart. With that, we can avoid looking for restartable queues, if we don't have to. Max reports that this restores performance. Before this patch, 4K IOPS was limited to 22-23K IOPS. With the patch, we are running at 950-970K IOPS. Fixes: 6d8c6c0f97ad ("blk-mq: Restart a single queue if tag sets are shared") Reported-by: Max Gurtovoy <maxg@mellanox.com> Tested-by: Max Gurtovoy <maxg@mellanox.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Tested-by: Bart Van Assche <bart.vanassche@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18blk-mq: refactor blk_mq_sched_assign_iocChristoph Hellwig
blk_mq_sched_assign_ioc now only handles the assigned of the ioc if the schedule needs it (bfq only at the moment). The caller to the per-request initializer is moved out so that it can be merged with a similar call for the kyber I/O scheduler. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18blk-mq: remove blk_mq_sched_{get,put}_rq_privChristoph Hellwig
Having these as separate helpers in a header really does not help readability, or my chances to refactor this code sanely. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18blk-mq: move blk_mq_sched_{get,put}_request to blk-mq.cChristoph Hellwig
Having them out of line in blk-mq-sched.c just makes the code flow unnecessarily complicated. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-05-26blk-mq: make per-sw-queue bio merge as default .bio_mergeMing Lei
Because what the per-sw-queue bio merge does is basically same with scheduler's .bio_merge(), this patch makes per-sw-queue bio merge as the default .bio_merge if no scheduler is used or io scheduler doesn't provide .bio_merge(). Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-20blk-mq: Remove blk_mq_sched_move_to_dispatch()Bart Van Assche
commit c13660a08c8b ("blk-mq-sched: change ->dispatch_requests() to ->dispatch_request()") removed the last user of this function. Hence also remove the function itself. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Omar Sandoval <osandov@fb.com> Cc: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-14blk-mq-sched: make completed_request() callback more usefulOmar Sandoval
Currently, this callback is called right after put_request() and has no distinguishable purpose. Instead, let's call it before put_request() as soon as I/O has completed on the request, before we account it in blk-stat. With this, Kyber can enable stats when it sees a latency outlier and make sure the outlier gets accounted. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07blk-mq-sched: provide hooks for initializing hardware queue dataOmar Sandoval
Schedulers need to be informed when a hardware queue is added or removed at runtime so they can allocate/free per-hardware queue data. So, replace the blk_mq_sched_init_hctx_data() helper, which only makes sense at init time, with .init_hctx() and .exit_hctx() hooks. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07blk-mq: Restart a single queue if tag sets are sharedBart Van Assche
To improve scalability, if hardware queues are shared, restart a single hardware queue in round-robin fashion. Rename blk_mq_sched_restart_queues() to reflect the new semantics. Remove blk_mq_sched_mark_restart_queue() because this function has no callers. Remove flag QUEUE_FLAG_RESTART because this patch removes the code that uses this flag. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07blk-mq-sched: fix crash in switch error pathOmar Sandoval
In elevator_switch(), if blk_mq_init_sched() fails, we attempt to fall back to the original scheduler. However, at this point, we've already torn down the original scheduler's tags, so this causes a crash. Doing the fallback like the legacy elevator path is much harder for mq, so fix it by just falling back to none, instead. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07blk-mq-sched: set up scheduler tags when bringing up new queuesOmar Sandoval
If a new hardware queue is added at runtime, we don't allocate scheduler tags for it, leading to a crash. This hooks up the scheduler framework to blk_mq_{init,exit}_hctx() to make sure everything gets properly initialized/freed. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07blk-mq-sched: refactor scheduler initializationOmar Sandoval
Preparation cleanup for the next couple of fixes, push blk_mq_sched_setup() and e->ops.mq.init_sched() into a helper. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-23blk-mq-sched: separate mark hctx and queue restart operationsOmar Sandoval
In blk_mq_sched_dispatch_requests(), we call blk_mq_sched_mark_restart() after we dispatch requests left over on our hardware queue dispatch list. This is so we'll go back and dispatch requests from the scheduler. In this case, it's only necessary to restart the hardware queue that we are running; there's no reason to run other hardware queues just because we are using shared tags. So, split out blk_mq_sched_mark_restart() into two operations, one for just the hardware queue and one for the whole request queue. The core code only needs the hctx variant, but I/O schedulers will want to use both. This also requires adjusting blk_mq_sched_restart_queues() to always check the queue restart flag, not just when using shared tags. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-10blk-mq: pass bio to blk_mq_sched_get_rq_privPaolo Valente
bio is used in bfq-mq's get_rq_priv, to get the request group. We could pass directly the group here, but I thought that passing the bio was more general, giving the possibility to get other pieces of information if needed. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-03block: free merged request in the callerJens Axboe
If we end up doing a request-to-request merge when we have completed a bio-to-request merge, we free the request from deep down in that path. For blk-mq-sched, the merge path has to hold the appropriate lock, but we don't need it for freeing the request. And in fact holding the lock is problematic, since we are now calling the mq sched put_rq_private() hook with the lock held. Other call paths do not hold this lock. Fix this inconsistency by ensuring that the caller frees a merged request. Then we can do it outside of the lock, making it both more efficient and fixing the blk-mq-sched problem of invoking parts of the scheduler with an unknown lock state. Reported-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
2017-02-02blk-mq-sched: bypass the scheduler for flushes entirelyOmar Sandoval
There's a weird inconsistency that flushes are mostly hidden from the scheduler, but it needs to be aware of them in ->insert_requests(). Instead of having every scheduler call blk_mq_sched_bypass_insert(), let's do it in the common framework. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-27blk-mq-sched: add flush insertion into blk_mq_sched_insert_request()Jens Axboe
Instead of letting the caller check this and handle the details of inserting a flush request, put the logic in the scheduler insertion function. This fixes direct flush insertion outside of the usual make_request_fn calls, like from dm via blk_insert_cloned_request(). Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-27blk-mq-sched: fix starvation for multiple hardware queues and shared tagsJens Axboe
If we have both multiple hardware queues and shared tag map between devices, we need to ensure that we propagate the hardware queue restart bit higher up. This is because we can get into a situation where we don't have any IO pending on a hardware queue, yet we fail getting a tag to start new IO. If that happens, it's not enough to mark the hardware queue as needing a restart, we need to bubble that up to the higher level queue as well. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Tested-by: Hannes Reinecke <hare@suse.com>
2017-01-17blk-mq-sched: allow setting of default IO schedulerJens Axboe
Add Kconfig entries to manage what devices get assigned an MQ scheduler, and add a blk-mq flag for drivers to opt out of scheduling. The latter is useful for admin type queues that still allocate a blk-mq queue and tag set, but aren't use for normal IO. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
2017-01-17blk-mq-sched: add framework for MQ capable IO schedulersJens Axboe
This adds a set of hooks that intercepts the blk-mq path of allocating/inserting/issuing/completing requests, allowing us to develop a scheduler within that framework. We reuse the existing elevator scheduler API on the registration side, but augment that with the scheduler flagging support for the blk-mq interfce, and with a separate set of ops hooks for MQ devices. We split driver and scheduler tags, so we can run the scheduling independently of device queue depth. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com>