From: Stephane Eranian <eranian@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@elte.hu, linux-kernel@vger.kernel.org, paulus@samba.org,
robert.richter@amd.com, fweisbec@gmail.com
Subject: Re: [RFC][PATCH 08/11] perf, x86: Implement simple LBR support
Date: Thu, 4 Mar 2010 09:54:04 -0800 [thread overview]
Message-ID: <bd4cb8901003040954n5b05e139wa24f8e50789421ac@mail.gmail.com> (raw)
In-Reply-To: <1267693107.25158.149.camel@laptop>
On Thu, Mar 4, 2010 at 12:58 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, 2010-03-03 at 22:57 +0100, Stephane Eranian wrote:
>> I don't understand how LBR state is migrated when a per-thread event is moved
>> from one CPU to another. It seems LBR is managed per-cpu.
>>
>> Can you explain this to me?
>
> It is not, its basically impossible to do given that the TOS doesn't
> count more bits than is strictly needed.
>
I don't get that about the TOS.
So you are saying that one context switch out, you drop the current
content of LBR. When you are scheduled back in on an another CPU,
you grab whatever is there?
> Or we should stop supporting cpu and task users at the same time.
>
Or you should consider LBR as an event which has a constraint that
it can only run on one pseudo counter (similar to what you do with
BTS). Scheduling would take care of the mutual exclusion. Multiplexing
would provide the work-around.
next prev parent reply other threads:[~2010-03-04 17:54 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-03 16:39 [RFC][PATCH 00/11] Another stab at PEBS and LBR support Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 01/11] perf, x86: Remove superfluous arguments to x86_perf_event_set_period() Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 02/11] perf, x86: Remove superfluous arguments to x86_perf_event_update() Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 03/11] perf, x86: Change x86_pmu.{enable,disable} calling convention Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 04/11] perf, x86: Use unlocked bitops Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 05/11] perf: Generic perf_sample_data initialization Peter Zijlstra
2010-03-03 16:49 ` David Miller
2010-03-03 21:14 ` Frederic Weisbecker
2010-03-05 8:44 ` Jean Pihet
2010-03-03 16:39 ` [RFC][PATCH 06/11] perf, x86: PEBS infrastructure Peter Zijlstra
2010-03-03 17:38 ` Robert Richter
2010-03-03 17:42 ` Peter Zijlstra
2010-03-04 8:50 ` Robert Richter
2010-03-03 16:39 ` [RFC][PATCH 07/11] perf: Provide PERF_SAMPLE_REGS Peter Zijlstra
2010-03-03 17:30 ` Stephane Eranian
2010-03-03 17:39 ` Peter Zijlstra
2010-03-03 17:49 ` Stephane Eranian
2010-03-03 17:55 ` David Miller
2010-03-03 18:18 ` Stephane Eranian
2010-03-03 19:18 ` Peter Zijlstra
2010-03-04 2:59 ` Ingo Molnar
2010-03-04 12:58 ` Arnaldo Carvalho de Melo
2010-03-03 22:02 ` Frederic Weisbecker
2010-03-04 8:58 ` Peter Zijlstra
2010-03-04 11:04 ` Ingo Molnar
2010-03-03 16:39 ` [RFC][PATCH 08/11] perf, x86: Implement simple LBR support Peter Zijlstra
2010-03-03 21:52 ` Stephane Eranian
2010-03-04 8:58 ` Peter Zijlstra
2010-03-03 21:57 ` Stephane Eranian
2010-03-04 8:58 ` Peter Zijlstra
2010-03-04 17:54 ` Stephane Eranian [this message]
2010-03-04 18:18 ` Peter Zijlstra
2010-03-04 20:23 ` Peter Zijlstra
2010-03-04 20:57 ` Stephane Eranian
2010-03-03 16:39 ` [RFC][PATCH 09/11] perf, x86: Implement PERF_SAMPLE_BRANCH_STACK Peter Zijlstra
2010-03-03 21:08 ` Frederic Weisbecker
2010-03-03 16:39 ` [RFC][PATCH 10/11] perf, x86: use LBR for PEBS IP+1 fixup Peter Zijlstra
2010-03-03 18:05 ` Masami Hiramatsu
2010-03-03 19:37 ` Peter Zijlstra
2010-03-03 21:11 ` Masami Hiramatsu
2010-03-03 21:50 ` Stephane Eranian
2010-03-04 8:57 ` Peter Zijlstra
2010-03-09 1:41 ` Stephane Eranian
2010-03-03 16:39 ` [RFC][PATCH 11/11] perf, x86: Clean up IA32_PERF_CAPABILITIES usage Peter Zijlstra
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=bd4cb8901003040954n5b05e139wa24f8e50789421ac@mail.gmail.com \
--to=eranian@google.com \
--cc=fweisbec@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=paulus@samba.org \
--cc=peterz@infradead.org \
--cc=robert.richter@amd.com \
/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;
as well as URLs for NNTP newsgroup(s).