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From: Manfred Spraul <manfred@colorfullife.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Page aging broken in 2.6
Date: Fri, 26 Dec 2003 11:45:22 +0100	[thread overview]
Message-ID: <3FEC1142.7050803@colorfullife.com> (raw)

Ben wrote:

>I can imagine that an architecture with TLBs will usually evict
>the entry from the TLB sooner or later and the accessed bit will end
>up beeing set again. On PPC, that isn't the case, the entry can well
>stay a loooong time in the hash and if not evicted, _PAGE_ACCESSED
>will never be set again.
>
One risk for i386 are the huge tlbs that AMD uses (512 entries?) - hot 
pages might stay in the TLB forever.

>Or does it snoop accesses
>to the PTE to "catch" somebody clearing the bits ?
>
No. AMD K8 cpu partially snoop PDE/PTE accesses and ignore tlb flush 
instructions if they are certain that the tlb is valid, but I'm not 
aware that anyone snoops the complete tlb cache.

--
    Manfred


             reply	other threads:[~2003-12-26 10:45 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-12-26 10:45 Manfred Spraul [this message]
  -- strict thread matches above, loose matches on Subject: below --
2003-12-26  7:28 Page aging broken in 2.6 Benjamin Herrenschmidt
2003-12-26  7:40 ` Andrew Morton
2003-12-26  9:21   ` Arjan van de Ven
2003-12-26  9:58     ` Benjamin Herrenschmidt
2003-12-26 19:44     ` Davide Libenzi
2003-12-26  9:33   ` Russell King
2003-12-26 10:07     ` Benjamin Herrenschmidt
2003-12-26 17:59 ` Linus Torvalds
2003-12-26 23:55   ` Benjamin Herrenschmidt
2003-12-27  0:35     ` Linus Torvalds
2003-12-27  0:44       ` Benjamin Herrenschmidt
2003-12-27  0:53         ` Linus Torvalds
2003-12-27  0:59           ` Linus Torvalds
2003-12-27  1:03           ` Benjamin Herrenschmidt
2003-12-27  2:37             ` Andrea Arcangeli
2003-12-27  5:02               ` Benjamin Herrenschmidt
2003-12-27 10:16               ` William Lee Irwin III
2003-12-27  2:47           ` Rik van Riel
2003-12-27  3:00             ` Andrew Morton
2003-12-27  3:31               ` Rik van Riel
2003-12-27  3:54               ` Linus Torvalds
2003-12-27 16:34                 ` Martin J. Bligh
2003-12-27 23:07               ` Roger Luethi
2003-12-27 23:55                 ` William Lee Irwin III
2003-12-28 11:23                   ` Roger Luethi
2003-12-28 16:35                     ` William Lee Irwin III
2003-12-28 17:15                       ` Roger Luethi
2003-12-28  0:04                 ` Andrew Morton
2003-12-28 11:58                   ` Roger Luethi
2003-12-27  1:41       ` Andrea Arcangeli

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