Commit-ID: e72daf3f4d764c47fb71c9bdc7f9c54a503825b1 Gitweb: http://git.kernel.org/tip/e72daf3f4d764c47fb71c9bdc7f9c54a503825b1 Author: Jiri Olsa <jolsa@xxxxxxxxxx> AuthorDate: Tue, 1 Mar 2016 20:03:52 +0100 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Tue, 8 Mar 2016 12:18:32 +0100 perf/x86/intel: Use PAGE_SIZE for PEBS buffer size on Core2 Using PAGE_SIZE buffers makes the WRMSR to PERF_GLOBAL_CTRL in intel_pmu_enable_all() mysteriously hang on Core2. As a workaround, we don't do this. The hard lockup is easily triggered by running 'perf test attr' repeatedly. Most of the time it gets stuck on sample session with small periods. # perf test attr -vv 14: struct perf_event_attr setup : --- start --- ... 'PERF_TEST_ATTR=/tmp/tmpuEKz3B /usr/bin/perf record -o /tmp/tmpuEKz3B/perf.data -c 123 kill >/dev/null 2>&1' ret 1 Reported-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Kan Liang <kan.liang@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Stephane Eranian <eranian@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vince Weaver <vincent.weaver@xxxxxxxxx> Cc: Wang Nan <wangnan0@xxxxxxxxxx> Link: http://lkml.kernel.org/r/20160301190352.GA8355@xxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/events/intel/ds.c | 13 +++++++++++-- arch/x86/events/perf_event.h | 1 + 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index c8a243d..22ece02 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -269,7 +269,7 @@ static int alloc_pebs_buffer(int cpu) if (!x86_pmu.pebs) return 0; - buffer = kzalloc_node(PEBS_BUFFER_SIZE, GFP_KERNEL, node); + buffer = kzalloc_node(x86_pmu.pebs_buffer_size, GFP_KERNEL, node); if (unlikely(!buffer)) return -ENOMEM; @@ -286,7 +286,7 @@ static int alloc_pebs_buffer(int cpu) per_cpu(insn_buffer, cpu) = ibuffer; } - max = PEBS_BUFFER_SIZE / x86_pmu.pebs_record_size; + max = x86_pmu.pebs_buffer_size / x86_pmu.pebs_record_size; ds->pebs_buffer_base = (u64)(unsigned long)buffer; ds->pebs_index = ds->pebs_buffer_base; @@ -1319,6 +1319,7 @@ void __init intel_ds_init(void) x86_pmu.bts = boot_cpu_has(X86_FEATURE_BTS); x86_pmu.pebs = boot_cpu_has(X86_FEATURE_PEBS); + x86_pmu.pebs_buffer_size = PEBS_BUFFER_SIZE; if (x86_pmu.pebs) { char pebs_type = x86_pmu.intel_cap.pebs_trap ? '+' : '-'; int format = x86_pmu.intel_cap.pebs_format; @@ -1327,6 +1328,14 @@ void __init intel_ds_init(void) case 0: pr_cont("PEBS fmt0%c, ", pebs_type); x86_pmu.pebs_record_size = sizeof(struct pebs_record_core); + /* + * Using >PAGE_SIZE buffers makes the WRMSR to + * PERF_GLOBAL_CTRL in intel_pmu_enable_all() + * mysteriously hang on Core2. + * + * As a workaround, we don't do this. + */ + x86_pmu.pebs_buffer_size = PAGE_SIZE; x86_pmu.drain_pebs = intel_pmu_drain_pebs_core; break; diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index 7bb61e3..1ab6279 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -586,6 +586,7 @@ struct x86_pmu { pebs_broken :1, pebs_prec_dist :1; int pebs_record_size; + int pebs_buffer_size; void (*drain_pebs)(struct pt_regs *regs); struct event_constraint *pebs_constraints; void (*pebs_aliases)(struct perf_event *event); -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html