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From: Andrew Morton <akpm@osdl.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [BUG] slab debug vs. L1 alignement
Date: Fri, 15 Aug 2003 14:16:14 -0700	[thread overview]
Message-ID: <20030815141614.29fc6768.akpm@osdl.org> (raw)
In-Reply-To: <1060956004.581.13.camel@gaston>

Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
>
> Currently, when enabling slab debugging, we lose the property of
> having the objects aligned on a cache line size.
> 
> This is, imho, an error, especially if GFP_DMA is passed. Such an
> object _must_ be cache alined (and it's size rounded to a multiple
> of the cache line size).

Well the theory is that SLAB_HWCACHE_ALIGN is advisory and
SLAB_MUST_HWCACHE_ALIGN is compulsory.

You're looking for compulsory alignment on the generic kmalloc() slab
pools, so we're a bit screwed.

I guess the redzoning would need to be taught to always pad by a full
cacheline.


  parent reply	other threads:[~2003-08-15 21:30 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-08-15 14:00 Benjamin Herrenschmidt
2003-08-15 18:51 ` Philippe Elie
2003-08-15 16:54   ` Benjamin Herrenschmidt
2003-08-15 21:16 ` Andrew Morton [this message]
2003-08-15 21:50 Manfred Spraul
2003-08-15 23:41 ` Benjamin Herrenschmidt
2003-08-16  1:47   ` Manfred Spraul
2003-08-16  9:37     ` Benjamin Herrenschmidt
2003-08-16 10:09       ` Manfred Spraul
2003-08-16 10:43         ` Benjamin Herrenschmidt
2003-08-16 11:21           ` Kai Makisara
2003-08-16 11:36             ` Benjamin Herrenschmidt
2003-08-16 14:39               ` Kai Makisara
     [not found] <kUMe.2pd.9@gated-at.bofh.it>
     [not found] ` <kWuz.41M.5@gated-at.bofh.it>
     [not found]   ` <kYwo.5Xr.1@gated-at.bofh.it>
     [not found]     ` <l5HD.4tl.21@gated-at.bofh.it>
     [not found]       ` <l6kd.53T.1@gated-at.bofh.it>
2003-08-16 12:00         ` Arnd Bergmann
2003-08-16 12:18           ` Manfred Spraul
2003-08-17 17:27 James Bottomley
2003-08-18 20:29 ` Kai Makisara
2003-09-30 18:40 ` Manfred Spraul

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