From: Andrew Morton <akpm@linux-foundation.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Miller <davem@davemloft.net>,
clameter@sgi.com, hugh@veritas.com, James.Bottomley@steeleye.com,
rmk+lkml@arm.linux.org.uk, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Containment measures for slab objects on scatter gather lists
Date: Fri, 29 Jun 2007 13:45:29 -0700 [thread overview]
Message-ID: <20070629134529.3e12a131.akpm@linux-foundation.org> (raw)
In-Reply-To: <20070629131657.5ecc3baa@the-village.bc.nu>
On Fri, 29 Jun 2007 13:16:57 +0100
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> > If those operations involve modifying that slab page's pageframe then what
> > stops concurrent dma'ers from stomping on each other's changes? As in:
> > why aren't we already buggy?
>
> Or DMA operations falling out with CPU operations in the same memory
> area. Not all platforms have hardware consistency and some will blat the
> entire page out of cache.
Is that just a performance problem, or can data be lost here? It depends
on the meaning of "blat": writeback? invalidate? More details, please.
I'm dyin here and nobody will talk to me. If the kernel is already doing
these things, why aren't we already buggy? Is it because we don't actually
modify the pageframes of these dma-to-from-kmalloced pages? But we were
thinking of doing so in the future?
next prev parent reply other threads:[~2007-06-29 20:46 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-29 4:01 [PATCH] Containment measures for slab objects on scatter gather lists Christoph Lameter
2007-06-29 4:10 ` David Miller
2007-06-29 4:22 ` Christoph Lameter
2007-06-29 4:28 ` David Miller
2007-06-29 4:39 ` Christoph Lameter
2007-06-29 5:06 ` David Miller
2007-06-29 5:24 ` Andrew Morton
2007-06-29 5:37 ` David Miller
2007-06-29 5:45 ` Andrew Morton
2007-06-29 6:51 ` Christoph Lameter
2007-06-29 12:16 ` Alan Cox
2007-06-29 20:45 ` Andrew Morton [this message]
2007-06-29 21:14 ` Russell King
2007-06-29 23:11 ` Alan Cox
2007-06-30 7:54 ` Russell King
2007-06-29 22:39 ` Alan Cox
2007-06-29 6:50 ` Christoph Lameter
2007-06-30 8:49 ` Christoph Hellwig
2007-06-29 7:00 ` Christoph Lameter
2007-06-29 9:06 ` David Miller
2007-06-29 13:04 ` Hugh Dickins
2007-06-29 14:15 ` Christoph Lameter
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