From: David Ahern <dsahern@gmail.com>
To: Alexander Yarygin <yarygin@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
Paul Mackerras <paulus@samba.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH RFC] perf kvm stat live: cache mmap()ed events
Date: Sun, 14 Sep 2014 09:39:37 -0600 [thread overview]
Message-ID: <5415B6B9.2040607@gmail.com> (raw)
In-Reply-To: <1410539263-25857-1-git-send-email-yarygin@linux.vnet.ibm.com>
On 9/12/14, 10:27 AM, Alexander Yarygin wrote:
> During mmap() process 'perf kvm stat live' gets a pointer to events and
> passes them to the session queue. Events are stored in shared memory and
> eventually they will be overwritten by the kernel. The problem is, that
> when events come too fast, old events can be overwritten before they
> have been processed that can lead to perf crash.
>
> To prevent that happening, we can copy upcoming events and pass a copy
> to the session queue. There is a safe place to copy event: before
> perf_evlist__mmap_consume() is executed. There are 3 places to free it:
> when event is processed, when it's lost and on exit, if it's turned out
> unprocessed.
Did you see what I proposed a year ago:
https://lkml.org/lkml/2013/9/6/388
The intent is to keep the copy generic and not local a command since
conceptually other live commands need the same.
David
next prev parent reply other threads:[~2014-09-14 15:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-12 16:27 [PATCH RFC] perf kvm stat live: cache mmap()ed events Alexander Yarygin
2014-09-14 13:24 ` Jiri Olsa
2014-09-14 15:39 ` David Ahern [this message]
2014-09-15 12:57 ` Alexander Yarygin
2014-09-15 14:23 ` David Ahern
2014-09-15 18:45 ` Arnaldo Carvalho de Melo
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