From: Olof Johansson <olof@lixom•net>
To: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom•com>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: [PATCH] [POWERPC] Emulate isel (Integer Select) instruction
Date: Tue, 27 Nov 2007 09:23:17 -0600 [thread overview]
Message-ID: <20071127152317.GA5230@lixom.net> (raw)
In-Reply-To: <Pine.LNX.4.62.0711271555520.5847@pademelon.sonytel.be>
On Tue, Nov 27, 2007 at 03:56:53PM +0100, Geert Uytterhoeven wrote:
> On Wed, 21 Nov 2007, Geert Uytterhoeven wrote:
> > On Tue, 20 Nov 2007, Kumar Gala wrote:
> > > On Nov 20, 2007, at 11:54 AM, Scott Wood wrote:
> > > > On Mon, Nov 19, 2007 at 09:36:57PM -0600, Kumar Gala wrote:
> > > >> isel (Integer Select) is a new user space instruction in the
> > > >> PowerISA 2.04 spec. Not all processors implement it so lets emulate
> > > >> to ensure code built with isel will run everywhere.
> > > >
> > > > Given that the instruction is meant to be a performance enhancement,
> > > > we should probably warn the first few times it's emulated, so the user
> > > > knows they should change their toolchain setup if possible.
> > >
> > > The same is true of mcrxr, popcntb, and possibly string ld/st.
> > >
> > > Feel free to submit a patch that warns about their usage.
> >
> > Something like this?
>
> New version below.
>
> Do we want it in sysfs? Or should we use debugfs instead?
I like this, and I'd say it's useful to have in sysfs. Few production
systems enable debugfs, and this is something that could be useful to
have access to there.
> Subject: powerpc: Keep track of emulated instructions
>
> From: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom•com>
>
> powerpc: Keep track of emulated instructions
>
> Counters for the various classes of emulated instructions are available under
> /sys/devices/system/cpu/cpu*/emulated/.
> Optionally, rate-limited warnings can be printed to the console when
> instructions are emulated.
>
> Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom•com>
> ---
> arch/powerpc/Kconfig.debug | 10 ++++++
> arch/powerpc/kernel/align.c | 17 ++++++++--
> arch/powerpc/kernel/sysfs.c | 64 ++++++++++++++++++++++++++++++++++++++++-
> arch/powerpc/kernel/traps.c | 17 +++++++++-
> include/asm-powerpc/emulator.h | 60 ++++++++++++++++++++++++++++++++++++++
This name stood out as being a bit too generic, emulator could mean
system support for running under some sort of emulator as well. How
about emulated_ops.h?
> +config DEBUG_WARN_EMULATED
> + bool "Warn if emulated instructions are used"
> + depends on DEBUG_KERNEL && SYSFS
> + help
> + This option will cause messages to be printed if an instruction is
> + emulated.
> + Counters for emulated instruction usages are always available under
> + /sys/devices/system/cpu/cpu*/emulated/, irrespective of the state
> + of this option.
How about making it a sysctl instead, so it can be flipped at runtime
(but default off)?
-Olof
next prev parent reply other threads:[~2007-11-27 15:20 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-20 3:36 [PATCH] [POWERPC] Emulate isel (Integer Select) instruction Kumar Gala
2007-11-20 17:54 ` Scott Wood
2007-11-20 21:01 ` Kumar Gala
2007-11-21 9:12 ` Benjamin Herrenschmidt
2007-11-21 14:19 ` Kumar Gala
2007-11-21 13:09 ` Geert Uytterhoeven
2007-11-21 14:22 ` Kumar Gala
2007-11-21 14:33 ` Geert Uytterhoeven
2007-11-21 15:34 ` Kumar Gala
2007-11-21 16:50 ` Geert Uytterhoeven
2007-11-21 19:22 ` Kumar Gala
2007-11-21 21:31 ` Paul Mackerras
2007-11-21 21:36 ` Paul Mackerras
2007-11-21 21:41 ` Scott Wood
2007-11-21 21:48 ` Kim Phillips
2007-11-21 21:38 ` Paul Mackerras
2007-11-27 14:56 ` Geert Uytterhoeven
2007-11-27 15:23 ` Olof Johansson [this message]
2007-11-28 10:49 ` Geert Uytterhoeven
2007-11-29 15:13 ` Geert Uytterhoeven
2007-12-14 8:12 ` Olof Johansson
2007-12-14 8:08 ` Kumar Gala
2007-12-14 8:17 ` Olof Johansson
2007-12-14 8:16 ` Olof Johansson
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=20071127152317.GA5230@lixom.net \
--to=olof@lixom$(echo .)net \
--cc=Geert.Uytterhoeven@sonycom$(echo .)com \
--cc=linuxppc-dev@ozlabs$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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