All of lore.kernel.org
 help / color / mirror / Atom feed
From: Anton Blanchard <anton@samba.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au,
	agraf@suse.de, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc: Align hot loops of memset() and backwards_memcpy()
Date: Sun, 25 Sep 2016 21:36:59 +1000	[thread overview]
Message-ID: <20160925213659.18971b96@kryten> (raw)
In-Reply-To: <20160805210052.0f9a8c43@roar.ozlabs.ibm.com>

Hi Nick,

> Hmm. If we execute this loop once, we'll only fetch additional nops.
> Twice, and we make up for them by not fetching unused instructions.
> More than twice and we may start winning.
> 
> For large sizes it probably helps, but I'd like to see what sizes
> memset sees.

I noticed this in an nginx web serving test. There are some 1 and 2
iteration calls, but quite a few larger ones - get_empty_filp() goes for
4 iterations and sk_prot_alloc() for 26 iterations.

Anton

  parent reply	other threads:[~2016-09-25 11:37 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-04  6:53 [PATCH] powerpc: Align hot loops of memset() and backwards_memcpy() Anton Blanchard
2016-08-04  7:49 ` Christophe Leroy
2016-08-04 10:36   ` Anton Blanchard
2016-08-05 11:00 ` Nicholas Piggin
2016-08-05 11:54   ` Anton Blanchard
2016-09-25 11:36   ` Anton Blanchard [this message]
2016-09-27 19:03     ` Nicholas Piggin
2016-10-05  2:36 ` Michael Ellerman

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=20160925213659.18971b96@kryten \
    --to=anton@samba.org \
    --cc=agraf@suse.de \
    --cc=benh@kernel.crashing.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mpe@ellerman.id.au \
    --cc=npiggin@gmail.com \
    --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 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.