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
next prev 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
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