From: David Miller <davem@davemloft.net>
To: akpm@linux-foundation.org
Cc: 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: Thu, 28 Jun 2007 22:37:34 -0700 (PDT) [thread overview]
Message-ID: <20070628.223734.21928089.davem@davemloft.net> (raw)
In-Reply-To: <20070628222424.4cbae90c.akpm@linux-foundation.org>
From: Andrew Morton <akpm@linux-foundation.org>
Date: Thu, 28 Jun 2007 22:24:24 -0700
> So what happens when two quite different threads of control are doing
> IO against two hunks of kmalloced memory which happen to come from the same
> page? Either some (kernel-wide) locking is needed, or that pageframe needs
> to be treated as readonly?
Or you put an atomic_t at the beginning or tail of every SLAB
object. It's a space cost not a runtime cost for the common
case which is:
smp_rmb();
if (atomic_read(&slab_obj->count) == 1)
really_free_it();
else if (atomic_dec_and_test(...))
Note I don't like this variant either. :)
next prev parent reply other threads:[~2007-06-29 5:37 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 [this message]
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
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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