From: Peter Zijlstra <peterz@infradead.org>
To: "Liang, Kan" <kan.liang@intel.com>
Cc: "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: Tue, 5 May 2015 19:00:47 +0200 [thread overview]
Message-ID: <20150505170047.GP23123@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <37D7C6CF3E00A74B8858931C1DB2F0770180BC7E@SHSMSX103.ccr.corp.intel.com>
On Tue, May 05, 2015 at 04:36:51PM +0000, Liang, Kan wrote:
> > > RECORDs are generic, and should live in the core code.
> > >
> > > Also, you should introduce this RECORD in a separate patch.
> >
> > On that, this is lacking a RECORD definition in
> > include/uapi/linux/perf_event.h:perf_event_type
>
> The PERF_RECORD_LOST already defined in perf_event_type.
> Are you suggesting to add a new dedicated RECORD type, like PERF_RECORD_COLLISION?
Yes, this should be a new RECORD, LOST_SAMPLES maybe.
The thing is, LOST is about the ring-buffer running out of space, this
is very much not the case here. Reusing it like this creates the
situation where userspace cannot tell what happened, and that is a very
bad thing indeed.
What we want to convey is that we dropped/lost a (number of) sample(s).
So the objection against the RECORD_COLLISIONS name is that it names the
reason we did something, but not the something we did.
next prev parent reply other threads:[~2015-05-05 17:01 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150505170047.GP23123@twins.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=acme@infradead.org \
--cc=andi@firstfloor.org \
--cc=eranian@google.com \
--cc=kan.liang@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.