[patch] x86, perf: avoid spamming kernel log for bts buffer failure

David Rientjes
2014-06-30T23:04:13Z

It's unnecessary to excessively spam the kernel log anytime the BTS buffer
cannot be allocated, so make this allocation __GFP_NOWARN.

The user probably will want to at least find some artifact that the
allocation has failed in the past, probably due to fragmentation because
of its large size, when it's not allocated at bootstrap. Thus, add a
WARN_ONCE() so something is left behind for them to understand why perf
commnads that require PEBS is not working properly.

Signed-off-by: David Rientjes <rientjes@google.com>
---
arch/x86/kernel/cpu/perf_event_intel_ds.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -311,9 +311,11 @@ static int alloc_bts_buffer(int cpu)
if (!x86_pmu.bts)
return 0;

- buffer = kzalloc_node(BTS_BUFFER_SIZE, GFP_KERNEL, node);
- if (unlikely(!buffer))
+ buffer = kzalloc_node(BTS_BUFFER_SIZE, GFP_KERNEL | __GFP_NOWARN, node);
+ if (unlikely(!buffer)) {
+ WARN_ONCE(1, "%s: BTS buffer allocation failure\n", __func__);
return -ENOMEM;
+ }

max = BTS_BUFFER_SIZE / BTS_RECORD_SIZE;
thresh = max / 16;