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From: Ingo Molnar <mingo@elte.hu>
To: David Miller <davem@davemloft.net>
Cc: torvalds@linux-foundation.org, linux-arch@vger.kernel.org,
	benh@kernel.crashing.org, rmk@arm.linux.org.uk
Subject: Re: Software prefetching considered harmful
Date: Fri, 20 May 2011 01:34:00 +0200	[thread overview]
Message-ID: <20110519233400.GA1954@elte.hu> (raw)
In-Reply-To: <20110519.154700.1253349185128359804.davem@davemloft.net>


* David Miller <davem@davemloft.net> wrote:

> So, to reiterate, I think you should kill all the list handling
> prefetches off.

Agreed.

> What we can do is say "for this specific list use, prefetch does
> in fact help".  And provide an interface for that.  I imagine there
> are things like inode dirty writeback or some dcache stuff that
> walks large lists and for which prefetch might be appropriate.

I think the best 'interface' for that is to open-code the prefetch()
right into the loop. This way it becomes well documented and very
visible as well.

Thanks,

	Ingo

  reply	other threads:[~2011-05-19 23:34 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-19 17:12 Software prefetching considered harmful Linus Torvalds
2011-05-19 19:05 ` Linus Torvalds
2011-05-19 19:28   ` Ingo Molnar
2011-05-21  3:37     ` Michael Cree
2011-05-21  4:18       ` Benjamin Herrenschmidt
2011-05-21 10:42         ` Ingo Molnar
2011-05-19 19:32   ` David Miller
2011-05-19 19:38     ` Linus Torvalds
2011-05-19 19:47       ` David Miller
2011-05-19 23:34         ` Ingo Molnar [this message]
2011-05-20 16:01           ` Catalin Marinas
2011-05-20  1:42   ` Benjamin Herrenschmidt
2011-05-20  8:34     ` Ingo Molnar
2011-05-20  9:13       ` Benjamin Herrenschmidt

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