3.16.35-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Jiri Olsa <jo...@redhat.com>
commit e72daf3f4d764c47fb71c9bdc7f9c54a503825b1 upstream.
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 <a...@redhat.com>
Signed-off-by: Jiri Olsa <jo...@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Reviewed-by: Andi Kleen <a...@linux.intel.com>
Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Kan Liang <kan.li...@intel.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Stephane Eranian <eran...@google.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Vince Weaver <vincent.wea...@maine.edu>
Cc: Wang Nan <wangn...@huawei.com>
Link: http://lkml.kernel.org/r/20160301190352.ga8...@krava.redhat.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
arch/x86/kernel/cpu/perf_event_intel_ds.c | 13 +++++++++++--
arch/x86/kernel/cpu/perf_event.h | 1 +
2 files changed, 12 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -257,7 +257,7 @@ 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;
@@ -274,7 +274,7 @@ 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;
@@ -1065,6 +1065,7 @@ void 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;
@@ -1073,6 +1074,14 @@ void intel_ds_init(void)
case 0:
printk(KERN_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;
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -447,6 +447,7 @@ struct x86_pmu {
pebs_active :1,
pebs_broken :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);
