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From: Arnd Bergmann <arnd@arndb.de>
To: Manfred Spraul <manfred@colorfullife.com>,
	linux-kernel@vger.kernel.org,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Ravikiran G Thirumalai <kiran@in.ibm.com>
Subject: Re: [patch] Make slab allocator work with SLAB_MUST_HWCACHE_ALIGN
Date: Sun, 14 Sep 2003 00:18:02 +0200	[thread overview]
Message-ID: <200309132218.h8DMIBHj007826@post.webmailer.de> (raw)
In-Reply-To: voSF.8l7.17@gated-at.bofh.it

Manfred Spraul wrote:

> But back to the patch that started this thread: Do you still need the 
> ability to set an explicit alignment for slab allocations? If yes, then 
> I'd polish my patch, double check all kmem_cache_create callers and then 
> send the patch to akpm. Otherwise I'd wait - the patch is not a bugfix.

The explicit alignment would be my preferred way to fix slab debugging
on s390. We still have the problem that practically all s390 device drivers
need 64-bit alignment on slab allocations.

Our current hack is to redefine BYTES_PER_WORD in slab.c to 8, but what
I'd like to see is a per-architecture alignment in kmem_cache_init
that would default to 8 on s390 and to sizeof(long) otherwise.

Using the current SLAB_MUST_HWCACHE_ALIGN is not an option since
it wastes a lot of memory with our 2048-bit L1 cache lines.
I'd also like to avoid creating special slab caches for anything
that needs 8-byte alignment.

        Arnd <><

       reply	other threads:[~2003-09-13 22:18 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <u8mV.so.19@gated-at.bofh.it>
     [not found] ` <ufor.30e.21@gated-at.bofh.it>
     [not found]   ` <usvj.6s9.17@gated-at.bofh.it>
     [not found]     ` <uxv1.5D5.23@gated-at.bofh.it>
     [not found]       ` <uCuI.5hY.13@gated-at.bofh.it>
     [not found]         ` <uRWI.xK.5@gated-at.bofh.it>
     [not found]           ` <voSF.8l7.17@gated-at.bofh.it>
2003-09-13 22:18             ` Arnd Bergmann [this message]
2003-09-10  8:16 How reliable is SLAB_HWCACHE_ALIGN? Ravikiran G Thirumalai
2003-09-10 15:41 ` Robert Love
2003-09-11  5:54   ` Ravikiran G Thirumalai
2003-09-11 11:08     ` [patch] Make slab allocator work with SLAB_MUST_HWCACHE_ALIGN Ravikiran G Thirumalai
2003-09-11 16:19       ` Manfred Spraul
2003-09-11 21:49         ` Manfred Spraul
2003-09-12  8:59         ` Ravikiran G Thirumalai
2003-09-12  9:10           ` Arjan van de Ven
2003-09-13 20:06           ` Manfred Spraul
2003-09-13 20:58             ` Dipankar Sarma
2003-09-14  8:09             ` Ravikiran G Thirumalai
2003-09-14 13:00               ` Dipankar Sarma
2003-09-15  5:13                 ` Ravikiran G Thirumalai

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