From: Manfred Spraul <manfred@colorfullife.com>
To: Andrew Morton <akpm@zip.com.au>
Cc: Dave Jones <davej@suse.de>, Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [patch] Prefetching file_read_actor()
Date: Mon, 31 Dec 2001 11:58:27 +0100 [thread overview]
Message-ID: <3C3044D3.EBEF6657@colorfullife.com> (raw)
In-Reply-To: <20011231033220.A1686@suse.de> <3C2FFB2F.D02095A2@zip.com.au>
Andrew Morton wrote:
>
>
> Is prefetching 4k at a time optimal? Should the prefetch be embedded
> in copy_*_user?
>
For the Pentium III, that's the Intel recommended sequence.
>
> The code makes no attempt to align the prefetch address to anything.
> Should it?
Not needed.
> What happens if a prefetch spills over the end of the page and
> faults?
>
Doesn't hurt, prefetch instruction never cause page faults.
BUT: Prefetch doesn't preload the TLB. If the TLB entry for the kmap is
not in the TLB, all prefetch instructions are treated as nops.(on pIII).
--
Manfred
next prev parent reply other threads:[~2001-12-31 10:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-12-31 3:32 [patch] Prefetching file_read_actor() Dave Jones
2001-12-31 5:44 ` Andrew Morton
2001-12-31 10:58 ` Manfred Spraul [this message]
2001-12-31 19:28 ` Andrew Morton
2001-12-31 19:47 ` Dave Jones
2001-12-31 20:40 ` Ryan Cumming
2002-01-01 10:29 ` Alan Cox
2002-01-01 12:45 ` Dave Jones
2002-01-01 15:26 ` Alan Cox
2002-01-01 10:30 ` Alan Cox
2002-01-01 11:08 ` Anton Blanchard
2001-12-31 20:31 ` Dave Jones
2001-12-31 13:00 ` Alan Cox
2001-12-31 12:50 ` Rik van Riel
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