From: Michael Neuling <mikey@neuling.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>, eranian@google.com
Cc: Linux PPC dev <linuxppc-dev@ozlabs.org>,
linux-kernel@vger.kernel.org,
Anshuman Khandual <anshuman.khandual@in.ibm.com>
Subject: Invalid perf_branch_entry.to entries question
Date: Tue, 07 May 2013 11:35:28 +1000 [thread overview]
Message-ID: <25394.1367890528@ale.ozlabs.ibm.com> (raw)
Peter & Stephane,
We are plumbing the POWER8 Branch History Rolling Buffer (BHRB) into
struct perf_branch_entry.
Sometimes on POWER8 we may not be able to fill out the "to" address. We
initially thought of just making this 0, but it's feasible that this
could be a valid address to branch to.
The other logical value to indicate an invalid entry would be all 1s
which is not possible (on POWER at least).
Do you guys have a preference as to what we should use as an invalid
entry? This would have some consequences for the userspace tool also.
The alternative would be to add a flag alongside mispred/predicted to
indicate the validity of the "to" address.
Mikey
next reply other threads:[~2013-05-07 1:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-07 1:35 Michael Neuling [this message]
2013-05-08 15:59 ` Invalid perf_branch_entry.to entries question Peter Zijlstra
2013-05-08 21:33 ` Stephane Eranian
2013-05-08 22:45 ` Michael Neuling
2013-05-09 0:02 ` Michael Ellerman
2013-05-08 22:39 ` Michael Neuling
2013-05-10 10:43 ` Peter Zijlstra
2013-05-10 10:50 ` Michael Neuling
2013-05-10 11:51 ` Benjamin Herrenschmidt
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=25394.1367890528@ale.ozlabs.ibm.com \
--to=mikey@neuling.org \
--cc=a.p.zijlstra@chello.nl \
--cc=anshuman.khandual@in.ibm.com \
--cc=eranian@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@ozlabs.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;
as well as URLs for NNTP newsgroup(s).