From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: linux-kernel@vger.kernel.org, kan.liang@intel.com, ak@linux.intel.com
Subject: Re: [PATCH] perf/x86/intel: fix ICL/SPR INST_RETIRED.PREC_DIST encodings
Date: Fri, 15 Oct 2021 12:27:58 +0200 [thread overview]
Message-ID: <YWlXrgxWeTsZ4g3w@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CABPqkBRWQ4cm3gmQf6AmoGKjPwjG9hVDXyt6L4CEUk6dkHTvDg@mail.gmail.com>
On Thu, Oct 14, 2021 at 11:01:15AM -0700, Stephane Eranian wrote:
> On Thu, Oct 14, 2021 at 3:09 AM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Wed, Oct 13, 2021 at 05:12:14PM -0700, Stephane Eranian wrote:
> > > This patch fixes the encoding for INST_RETIRED.PREC_DIST as published by Intel
> > > (download.01.org/perfmon/) for Icelake. The official encoding
> > > is event code 0x00 umask 0x1, a change from Skylake where it was code 0xc0
> > > umask 0x1.
> > >
> > > With this patch applied it is possible to run:
> > > $ perf record -a -e cpu/event=0x00,umask=0x1/pp .....
> > >
> > > Whereas before this would fail.
> > >
> > > To avoid problems with tools which may use the old code, we maintain the old
> > > encoding for Icelake.
> >
> > Uuuuhhhhh.. but we 'stole' event=0x00 for the fake events. There must
> > not be actual hardware events there or we're in trouble. I thought Intel
> > knew that, I'm sure I told them that.
>
> Yes, this is a pseudo event code. INST_RETIRED.PREC_DIST 0x0100 only
> works on fixed counter 0
> to deliver the better sample distribution.
Ah, okay. Thanks!
next prev parent reply other threads:[~2021-10-15 10:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-14 0:12 Stephane Eranian
2021-10-14 0:37 ` Andi Kleen
2021-10-14 10:09 ` Peter Zijlstra
2021-10-14 18:01 ` Stephane Eranian
2021-10-15 10:27 ` Peter Zijlstra [this message]
2021-10-30 14:40 ` [tip: perf/core] perf/x86/intel: Fix " tip-bot2 for Stephane Eranian
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=YWlXrgxWeTsZ4g3w@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=ak@linux.intel.com \
--cc=eranian@google.com \
--cc=kan.liang@intel.com \
--cc=linux-kernel@vger.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®