From: Alan Modra <amodra@gmail.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@ozlabs.org, paulus@samba.org,
Anton Blanchard <anton@samba.org>,
rostedt@goodmis.org, imunsie@au1.ibm.com
Subject: Re: PowerPC ftrace function trace optimisation
Date: Thu, 29 Apr 2010 10:52:52 +0930 [thread overview]
Message-ID: <20100429012252.GC3510@bubble.grove.modra.org> (raw)
In-Reply-To: <1272502967.24542.137.camel@pasglop>
On Thu, Apr 29, 2010 at 11:02:47AM +1000, Benjamin Herrenschmidt wrote:
> From a quick test it appears that this only works with -m64, not -m32.
> Alan is that correct ?
Yes.
> Any chance you can fix that in future gcc versions ?
No need really. 32-bit _mcount calls happen before the prologue
anyway.
> > In fact if we are careful when switching to the new mcount ABI and don't
> > rely on the store of r0, we could probably optimise this even further in a
> > future gcc and remove the store completely. mcount would be 2 instructions:
> >
> > mflr r0
> > bl 8 <.foo+0x8>
Yeah. Also, I should have used a different name for this mcount from
the standard 64-bit mcount.
--
Alan Modra
Australia Development Lab, IBM
next prev parent reply other threads:[~2010-04-29 1:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-29 0:51 PowerPC ftrace function trace optimisation Anton Blanchard
2010-04-29 1:02 ` Benjamin Herrenschmidt
2010-04-29 1:08 ` Benjamin Herrenschmidt
2010-04-29 1:22 ` Alan Modra [this message]
2010-04-29 1:55 ` Steven Rostedt
2010-04-29 2:10 ` 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=20100429012252.GC3510@bubble.grove.modra.org \
--to=amodra@gmail.com \
--cc=anton@samba.org \
--cc=benh@kernel.crashing.org \
--cc=imunsie@au1.ibm.com \
--cc=linuxppc-dev@ozlabs.org \
--cc=paulus@samba.org \
--cc=rostedt@goodmis.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 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.