From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
To: Michael Ellerman <michael@ellerman.id.au>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] powerpc: Partial revert of "Context switch more PMU related SPRs"
Date: Mon, 10 Jun 2013 09:48:17 +0530 [thread overview]
Message-ID: <51B55389.1080306@linux.vnet.ibm.com> (raw)
In-Reply-To: <1370491416-1807-1-git-send-email-michael@ellerman.id.au>
On 06/06/2013 09:33 AM, Michael Ellerman wrote:
> In commit 59affcd I added context switching of more PMU SPRs, because
> they are potentially exposed to userspace on Power8. However despite me
> being a smart arse in the commit message it's actually not correct. In
> particular it interacts badly with a global perf record.
Could you please explain how it would interact badly with a global perf record.
If any user space try to mess around with the MMCR* registers itself, it would
definitely interfere with the kernel's own PMU config going on during perf record.
But thats how it works. So when we are actually dealing with MMCR* registers
directly, we should not invoke "perf record" session which can potential run on
the same PMU.
Regards
Anshuman
prev parent reply other threads:[~2013-06-10 4:19 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-06 4:03 [PATCH] powerpc: Partial revert of "Context switch more PMU related SPRs" Michael Ellerman
2013-06-10 4:18 ` Anshuman Khandual [this message]
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=51B55389.1080306@linux.vnet.ibm.com \
--to=khandual@linux.vnet.ibm.com \
--cc=linuxppc-dev@ozlabs.org \
--cc=michael@ellerman.id.au \
/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.