From: david mosberger <dmosberger@gmail.com>
To: linux-ia64@vger.kernel.org
Subject: Re: Change ia64 prefetch to use lfetch.fault
Date: Fri, 29 Jul 2005 01:58:36 +0000 [thread overview]
Message-ID: <ed5aea430507281858377ea50a@mail.gmail.com> (raw)
In-Reply-To: <200507282153.j6SLr0g01028@unix-os.sc.intel.com>
No, it doesn't --- it actually hurt performance last time I measured
it. Basically, Linux uses prefetch() too often with bad/NULL
pointers, IIRC. Check my earlier mails where I fixed the IVT code to
properly handle lfetch.fault (from a couple of months ago).
--david
On 7/28/05, Chen, Kenneth W <kenneth.w.chen@intel.com> wrote:
> I don't remember whether this has been discussed earlier, won't
> it make sense to use the fault variant of lfetch for prefetch()
> and prefetchw()? After all, the caller has high confidence that
> the cache line will be used in the future.
>
>
> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
>
> --- linux-2.6.12/include/asm-ia64/processor.h.orig 2005-07-28 14:46:26.629519713 -0700
> +++ linux-2.6.12/include/asm-ia64/processor.h 2005-07-28 14:48:17.037721485 -0700
> @@ -682,13 +682,13 @@ ia64_imva (void *addr)
> static inline void
> prefetch (const void *x)
> {
> - ia64_lfetch(ia64_lfhint_none, x);
> + ia64_lfetch_fault(ia64_lfhint_none, x);
> }
>
> static inline void
> prefetchw (const void *x)
> {
> - ia64_lfetch_excl(ia64_lfhint_none, x);
> + ia64_lfetch_fault_excl(ia64_lfhint_none, x);
> }
>
> #define spin_lock_prefetch(x) prefetchw(x)
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
Mosberger Consulting LLC, voice/fax: 510-744-9372,
http://www.mosberger-consulting.com/
35706 Runckel Lane, Fremont, CA 94536
prev parent reply other threads:[~2005-07-29 1:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-28 21:53 Change ia64 prefetch to use lfetch.fault Chen, Kenneth W
2005-07-29 1:58 ` david mosberger [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=ed5aea430507281858377ea50a@mail.gmail.com \
--to=dmosberger@gmail.com \
--cc=linux-ia64@vger.kernel.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.