From 339ce1a4dc2ca26444c4f65c31b71a5056f3bb0b Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Mon, 18 Jan 2010 16:47:07 +1100 Subject: perf: Fix inconsistency between IP and callchain sampling When running perf across all cpus with backtracing (-a -g), sometimes we get samples without associated backtraces: 23.44% init [kernel] [k] restore 11.46% init eeba0c [k] 0x00000000eeba0c 6.77% swapper [kernel] [k] .perf_ctx_adjust_freq 5.73% init [kernel] [k] .__trace_hcall_entry 4.69% perf libc-2.9.so [.] 0x0000000006bb8c | |--11.11%-- 0xfffa941bbbc It turns out the backtrace code has a check for the idle task and the IP sampling does not. This creates problems when profiling an interrupt heavy workload (in my case 10Gbit ethernet) since we get no backtraces for interrupts received while idle (ie most of the workload). Right now x86 and sh check that current is not NULL, which should never happen so remove that too. Idle task's exclusion must be performed from the core code, on top of perf_event_attr:exclude_idle. Signed-off-by: Anton Blanchard Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Ingo Molnar Cc: Benjamin Herrenschmidt Cc: Paul Mundt LKML-Reference: <20100118054707.GT12666@kryten> Signed-off-by: Frederic Weisbecker --- arch/powerpc/kernel/perf_callchain.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/perf_callchain.c b/arch/powerpc/kernel/perf_callchain.c index a3c11cac3d7..95ad9dad298 100644 --- a/arch/powerpc/kernel/perf_callchain.c +++ b/arch/powerpc/kernel/perf_callchain.c @@ -495,9 +495,6 @@ struct perf_callchain_entry *perf_callchain(struct pt_regs *regs) entry->nr = 0; - if (current->pid == 0) /* idle task? */ - return entry; - if (!user_mode(regs)) { perf_callchain_kernel(regs, entry); if (current->mm) -- cgit v1.2.3 From 6e37738a2fac964583debe91099bc3248554f6e5 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 11 Feb 2010 13:21:58 +0100 Subject: perf_events: Simplify code by removing cpu argument to hw_perf_group_sched_in() Since the cpu argument to hw_perf_group_sched_in() is always smp_processor_id(), simplify the code a little by removing this argument and using the current cpu where needed. Signed-off-by: Peter Zijlstra Cc: David Miller Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Frederic Weisbecker LKML-Reference: <1265890918.5396.3.camel@laptop> Signed-off-by: Ingo Molnar --- arch/powerpc/kernel/perf_event.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/perf_event.c b/arch/powerpc/kernel/perf_event.c index 1eb85fbf53a..b6cf8f1f4d3 100644 --- a/arch/powerpc/kernel/perf_event.c +++ b/arch/powerpc/kernel/perf_event.c @@ -718,10 +718,10 @@ static int collect_events(struct perf_event *group, int max_count, return n; } -static void event_sched_in(struct perf_event *event, int cpu) +static void event_sched_in(struct perf_event *event) { event->state = PERF_EVENT_STATE_ACTIVE; - event->oncpu = cpu; + event->oncpu = smp_processor_id(); event->tstamp_running += event->ctx->time - event->tstamp_stopped; if (is_software_event(event)) event->pmu->enable(event); @@ -735,7 +735,7 @@ static void event_sched_in(struct perf_event *event, int cpu) */ int hw_perf_group_sched_in(struct perf_event *group_leader, struct perf_cpu_context *cpuctx, - struct perf_event_context *ctx, int cpu) + struct perf_event_context *ctx) { struct cpu_hw_events *cpuhw; long i, n, n0; @@ -766,10 +766,10 @@ int hw_perf_group_sched_in(struct perf_event *group_leader, cpuhw->event[i]->hw.config = cpuhw->events[i]; cpuctx->active_oncpu += n; n = 1; - event_sched_in(group_leader, cpu); + event_sched_in(group_leader); list_for_each_entry(sub, &group_leader->sibling_list, group_entry) { if (sub->state != PERF_EVENT_STATE_OFF) { - event_sched_in(sub, cpu); + event_sched_in(sub); ++n; } } -- cgit v1.2.3