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authorAlexei Starovoitov <ast@fb.com>2016-04-06 18:43:22 -0700
committerDavid S. Miller <davem@davemloft.net>2016-04-07 21:04:26 -0400
commitec5e099d6e941668d121ea9ca7057f4fa00830b0 (patch)
tree4ec273d88501a68ce23eb53649530161a7fa8440 /kernel
parentb33b0a1bf69faff89693df49519fa7b459f5d807 (diff)
perf: optimize perf_fetch_caller_regs
avoid memset in perf_fetch_caller_regs, since it's the critical path of all tracepoints. It's called from perf_sw_event_sched, perf_event_task_sched_in and all of perf_trace_##call with this_cpu_ptr(&__perf_regs[..]) which are zero initialized by perpcu init logic and subsequent call to perf_arch_fetch_caller_regs initializes the same fields on all archs, so we can safely drop memset from all of the above cases and move it into perf_ftrace_function_call that calls it with stack allocated pt_regs. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace_event_perf.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 00df25fd86ef..7a68afca8249 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -316,6 +316,7 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
+ memset(&regs, 0, sizeof(regs));
perf_fetch_caller_regs(&regs);
entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);