From: Andi Kleen <andi@firstfloor.org>
To: "Liang, Kan" <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
"mingo@kernel.org" <mingo@kernel.org>,
"acme@infradead.org" <acme@infradead.org>,
"eranian@google.com" <eranian@google.com>,
"andi@firstfloor.org" <andi@firstfloor.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V7 3/6] perf, x86: handle multiple records in PEBS buffer
Date: Wed, 6 May 2015 15:01:16 +0200 [thread overview]
Message-ID: <20150506130116.GM2366@two.firstfloor.org> (raw)
In-Reply-To: <37D7C6CF3E00A74B8858931C1DB2F0770180BB27@SHSMSX103.ccr.corp.intel.com>
> > > + if (p->status != (1 << bit)) {
> > > + u64 pebs_status;
> > > +
> > > + /* slow path */
> > > + pebs_status = p->status & cpuc->pebs_enabled;
> > > + pebs_status &= (1ULL << MAX_PEBS_EVENTS) - 1;
> > > + if (pebs_status != (1 << bit)) {
> > > + perf_log_lost(event);
> >
> > Does it make sense to keep an error[bit] count and only log once with the
> > actual number in? -- when !0 obviously.
>
> Yes, will do it.
If you use anything but u8 for the array member it would be too large
for the NMI stack, and u8 is lilkely overflow prone. Would not do it.
-Andi
next prev parent reply other threads:[~2015-05-06 13:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-20 8:07 [PATCH V7 0/6] large PEBS interrupt threshold Kan Liang
2015-04-20 8:07 ` [PATCH V7 1/6] perf, x86: use the PEBS auto reload mechanism when possible Kan Liang
2015-04-20 8:07 ` [PATCH V7 2/6] perf, x86: introduce setup_pebs_sample_data() Kan Liang
2015-04-20 8:07 ` [PATCH V7 3/6] perf, x86: handle multiple records in PEBS buffer Kan Liang
2015-05-05 13:07 ` Peter Zijlstra
2015-05-05 13:17 ` Peter Zijlstra
2015-05-05 16:36 ` Liang, Kan
2015-05-05 17:00 ` Peter Zijlstra
2015-05-05 13:16 ` Peter Zijlstra
2015-05-05 16:30 ` Liang, Kan
2015-05-05 17:08 ` Peter Zijlstra
2015-05-05 17:22 ` Liang, Kan
2015-05-06 13:01 ` Andi Kleen [this message]
2015-05-06 13:13 ` Peter Zijlstra
2015-04-20 8:07 ` [PATCH V7 4/6] perf, x86: large PEBS interrupt threshold Kan Liang
2015-04-20 8:07 ` [PATCH V7 5/6] perf, x86: drain PEBS buffer during context switch Kan Liang
2015-04-20 8:07 ` [PATCH V7 6/6] perf, x86: enlarge PEBS buffer Kan Liang
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