unofficial mirror of libc-alpha@sourceware.org
 help / color / mirror / Atom feed
From: naohirot--- via Libc-alpha <libc-alpha@sourceware.org>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Cc: 'GNU C Library' <libc-alpha@sourceware.org>
Subject: RE: [PATCH v3 5/5] AArch64: Improve A64FX memset
Date: Fri, 27 Aug 2021 05:05:03 +0000	[thread overview]
Message-ID: <TYAPR01MB6025CE96E52CDB35267A4A5ADFC89@TYAPR01MB6025.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <VE1PR08MB5599E453F6FAAE097CA3838E83C79@VE1PR08MB5599.eurprd08.prod.outlook.com>

Hi Wilco,

> > If you agree to the cmp and branch workaround (2 instructions at the beginning of the loop)
> > below, I'll submit a patch.
> 
> Yes, the 2 instruction workaround is clearly the best solution so far. It fixes the dips
> around 16KB but doesn't regress anything else. The results v4 vs v4fix [9] show there
> are even some uplifts in the 1-8KB range.

Thank you for the review. I submitted a patch [1], please find it.

[1] https://sourceware.org/pipermail/libc-alpha/2021-August/130569.html

> > 2) Result of the cmp and branch workaround (2 instructions at the beginning of the loop)
> 
> It's interesting this works on both systems, however it's still a mystery why...
> It would be a good idea to ask your CPU team about this.

OK. In the meanwhile you can find the microarchitecture manual [2] if you're interested in.

[2] https://github.com/fujitsu/A64FX/blob/master/doc/A64FX_Microarchitecture_Manual_en_1.5.pdf

Thanks.
Naohiro

      reply	other threads:[~2021-08-27  5:05 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-22 16:04 [PATCH v3 5/5] AArch64: Improve A64FX memset Wilco Dijkstra via Libc-alpha
2021-08-03 11:22 ` naohirot--- via Libc-alpha
2021-08-09 14:52   ` Wilco Dijkstra via Libc-alpha
2021-08-17  6:40     ` naohirot--- via Libc-alpha
2021-08-19 13:06       ` Wilco Dijkstra via Libc-alpha
2021-08-20  5:41         ` naohirot--- via Libc-alpha
2021-08-23 16:50           ` Wilco Dijkstra via Libc-alpha
2021-08-24  7:56             ` naohirot--- via Libc-alpha
2021-08-24  8:07               ` naohirot--- via Libc-alpha
2021-08-24 15:46               ` Wilco Dijkstra via Libc-alpha
2021-08-26  1:44                 ` naohirot--- via Libc-alpha
2021-08-26 14:13                   ` Wilco Dijkstra via Libc-alpha
2021-08-27  5:05                     ` naohirot--- via Libc-alpha [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

  List information: https://www.gnu.org/software/libc/involved.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=TYAPR01MB6025CE96E52CDB35267A4A5ADFC89@TYAPR01MB6025.jpnprd01.prod.outlook.com \
    --to=libc-alpha@sourceware.org \
    --cc=Wilco.Dijkstra@arm.com \
    --cc=naohirot@fujitsu.com \
    /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 read-only IMAP folder(s) and NNTP newsgroup(s).