perf: optimize perf_fetch_caller_regs

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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>

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Alexei Starovoitov 2016-04-06 18:43:22 -07:00 • committed by David S. Miller

parent b33b0a1bf6

commit ec5e099d6e

2 changed files with 1 additions and 2 deletions

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include/linux/perf_event.h

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1

kernel/trace/trace_event_perf.c

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