From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Bryan Rittmeyer <bryan@staidm.org>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>,
linuxppc-dev list <linuxppc-dev@lists.linuxppc.org>,
Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH] ppc32 copy_to_user dcbt fixup
Date: Sat, 13 Mar 2004 15:50:03 +1100 [thread overview]
Message-ID: <1079153403.2348.82.camel@gaston> (raw)
In-Reply-To: <20040313041547.GB11512@staidm.org>
> [1] csum_partial_copy_generic does not use dcbt/dcbz despite being
> scorching hot in TCP workloads. I'm cooking up another patch to
> dcb?ize it.
>
> [2] http://staidm.org/linux/ppc/copy_dcbt/copyuser-microbench.tar.bz2
I'll have a good look at it asap. Also, keep in mind that between the
dcbz and the time you can actually write to that cache line, some CPUs
may need some time to complete the L1 dcbz operation, which can lead
to poor performances, at least I've been told this is the case on
POWER3, maybe others. It would be wise to make the dcbz as long as
possible in "advance" before the actual write to the cache line.
Ben.
next prev parent reply other threads:[~2004-03-13 4:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-13 4:15 [PATCH] ppc32 copy_to_user dcbt fixup Bryan Rittmeyer
2004-03-13 4:50 ` Benjamin Herrenschmidt [this message]
2004-03-13 7:49 ` Bryan Rittmeyer
2004-03-13 8:36 ` Benjamin Herrenschmidt
2004-03-15 8:38 ` Segher Boessenkool
2004-03-13 9:11 ` Eugene Surovegin
2004-03-16 1:59 ` Bryan Rittmeyer
[not found] <1z8Na-5hH-1@gated-at.bofh.it>
2004-03-13 14:39 ` Danjel McGougan
2004-03-14 22:35 ` Bryan Rittmeyer
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