From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Eric B Munson <emunson@mgebm.net>
Cc: a.p.zijlstra@chello.nl, linux-kernel@vger.kernel.org,
paulus@samba.org, anton@samba.org, acme@ghostprotocols.net,
mingo@elte.hu, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] POWER: perf_event: Skip updating kernel counters if register value shrinks
Date: Wed, 30 Mar 2011 08:12:45 +1100 [thread overview]
Message-ID: <1301433165.2402.689.camel@pasglop> (raw)
In-Reply-To: <20110329142519.GA3527@mgebm.net>
On Tue, 2011-03-29 at 10:25 -0400, Eric B Munson wrote:
> Here I made the assumption that the hardware would never remove more events in
> a speculative roll back than it had added. This is not a situation I
> encoutered in my limited testing, so I didn't think underflow was possible. I
> will send out a V2 using the signed 32 bit delta and remeber to CC stable
> this time.
I'm not thinking about underflow but rollover... or that isn't possible
with those counters ? IE. They don't wrap back to 0 after hitting
ffffffff ?
Cheers,
Ben.
next prev parent reply other threads:[~2011-03-29 21:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-25 13:28 [PATCH] POWER: perf_event: Skip updating kernel counters if register value shrinks Eric B Munson
2011-03-29 6:03 ` Benjamin Herrenschmidt
2011-03-29 14:25 ` Eric B Munson
2011-03-29 21:12 ` Benjamin Herrenschmidt [this message]
2011-03-30 18:36 ` Eric B Munson
2011-03-31 6:04 ` Benjamin Herrenschmidt
2011-03-31 16:14 ` Eric B Munson
2011-04-06 21:27 ` Eric B Munson
2011-04-07 4:22 ` Benjamin Herrenschmidt
2011-04-07 16:16 ` Eric B Munson
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=1301433165.2402.689.camel@pasglop \
--to=benh@kernel.crashing.org \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@ghostprotocols.net \
--cc=anton@samba.org \
--cc=emunson@mgebm.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mingo@elte.hu \
--cc=paulus@samba.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).