From: Andi Kleen <ak@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org,
Frederic Weisbecker <fweisbec@gmail.com>,
Mike Galbraith <efault@gmx.de>, Paul Mackerras <paulus@samba.org>,
Stephane Eranian <eranian@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Matt Fleming <matt.fleming@intel.com>
Subject: Re: [PATCH v1 03/11] perf: Allow for multiple ring buffers per event
Date: Fri, 14 Mar 2014 07:13:00 -0700 [thread overview]
Message-ID: <20140314141300.GG3793@tassilo.jf.intel.com> (raw)
In-Reply-To: <20140314104415.GS27965@twins.programming.kicks-ass.net>
> > The other big problem is scalability. Even if it was somehow possible
> > to make this scheme work the IPIs for flushing would kill performance
> > on any multi threaded client. Given perf is not multi-threaded today, but
> > it doesn't seem a good idea to design the interface assuming no client ever
> > will be.
>
> Well any mmap()ed interface that wants to swap buffers will have this
> same problem.
There's no need to swap buffers in a sane design. The perf ring buffer
or the ftrace buffer don't need this. There's no need for a PT buffer
to do so either.
>
> You can restrict the TLB flushing to the threads that poll() on the
> relevant events. This just means other threads will see old/partial
> data, but that shouldn't be a problem as they shouldn't be looking in
> the first place.
Then we get incoherent processes. You're not serious about that are you?
-Andi
--
ak@linux.intel.com -- Speaking for myself only
next prev parent reply other threads:[~2014-03-14 14:13 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-06 10:50 [PATCH v1 00/11] perf: Add support for Intel Processor Trace Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 01/11] x86: Add Intel Processor Trace (INTEL_PT) cpu feature detection Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 02/11] perf: Abstract ring_buffer backing store operations Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 03/11] perf: Allow for multiple ring buffers per event Alexander Shishkin
2014-02-17 14:33 ` Peter Zijlstra
2014-02-18 2:36 ` Andi Kleen
2014-03-14 10:38 ` Peter Zijlstra
2014-03-14 14:10 ` Andi Kleen
2014-03-18 14:06 ` Alexander Shishkin
2014-02-19 22:02 ` Dave Hansen
2014-03-10 9:59 ` Alexander Shishkin
2014-03-10 17:24 ` Andi Kleen
2014-03-14 10:44 ` Peter Zijlstra
2014-03-14 14:13 ` Andi Kleen [this message]
2014-03-14 10:41 ` Peter Zijlstra
2014-05-07 15:26 ` Peter Zijlstra
2014-05-07 19:25 ` Ingo Molnar
2014-05-07 21:08 ` Andi Kleen
2014-05-07 21:22 ` Peter Zijlstra
2014-05-08 3:26 ` Alexander Shishkin
2014-05-08 4:05 ` Alexander Shishkin
2014-05-08 9:08 ` Alexander Shishkin
2014-05-08 12:34 ` Alexander Shishkin
2014-05-08 12:41 ` Peter Zijlstra
2014-05-08 12:46 ` Alexander Shishkin
2014-05-08 14:16 ` Peter Zijlstra
2014-02-06 10:50 ` [PATCH v1 04/11] itrace: Infrastructure for instruction flow tracing units Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 05/11] itrace: Add functionality to include traces in perf event samples Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 06/11] itrace: Add functionality to include traces in process core dumps Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 07/11] x86: perf: intel_pt: Intel PT PMU driver Alexander Shishkin
2014-02-06 20:29 ` Andi Kleen
2014-02-17 14:44 ` Peter Zijlstra
2014-02-17 16:07 ` Andi Kleen
2014-02-17 14:46 ` Peter Zijlstra
2014-02-18 12:42 ` Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 08/11] x86: perf: intel_pt: Add sampling functionality Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 09/11] x86: perf: intel_pt: Add core dump functionality Alexander Shishkin
2014-02-06 20:36 ` Andi Kleen
2014-02-07 9:03 ` Alexander Shishkin
2014-02-06 23:59 ` Andi Kleen
2014-02-07 9:09 ` Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 10/11] x86: perf: intel_bts: Add BTS PMU driver Alexander Shishkin
2014-02-06 10:50 ` [PATCH v1 11/11] x86: perf: intel_bts: Add core dump related functionality Alexander Shishkin
2014-02-06 23:57 ` Andi Kleen
2014-02-07 9:02 ` Alexander Shishkin
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=20140314141300.GG3793@tassilo.jf.intel.com \
--to=ak@linux.intel.com \
--cc=adrian.hunter@intel.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=dave.hansen@intel.com \
--cc=efault@gmx.de \
--cc=eranian@google.com \
--cc=fweisbec@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=matt.fleming@intel.com \
--cc=mingo@redhat.com \
--cc=paulus@samba.org \
--cc=peterz@infradead.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox