From: Tejun Heo <tj@kernel.org>
To: David Howells <dhowells@redhat.com>
Cc: torvalds@osdl.org, akpm@linux-foundation.org,
linux-am33-list@redhat.com, linux-kernel@vger.kernel.org,
Akira Takeuchi <takeuchi.akr@jp.panasonic.com>,
Mark Salter <msalter@redhat.com>
Subject: Re: [PATCH] MN10300: Fix the PERCPU() alignment to allow for workqueues
Date: Tue, 26 Oct 2010 16:56:49 +0200 [thread overview]
Message-ID: <4CC6EC31.4090304@kernel.org> (raw)
In-Reply-To: <14874.1288104642@redhat.com>
Hello, David.
On 10/26/2010 04:50 PM, David Howells wrote:
>>> FRV's page size is 16KB, so on that we really don't want it to be
>>> PAGE_SIZE.
>>
>> Why not? It's in the init section which will be freed anyway and with
>> the kernel image compression it's not even gonna add any noticeable
>> amount to the kernel image size. There isn't any benefit in using
>> anything smaller than PAGE_SIZE for alignment. Also, percpu allocator
>> guarantees alignment requirement upto PAGE_SIZE is honored. If the
>> output section uses smaller alignment, the percpu AS will end up being
>> misaligned.
>
> The bootloader we have doesn't do decompression.
I see. :-(
> On the other hand, does the PERCPU stuff need to be allocated space
> in the image by the linker? Can it be initialised to anything other
> than zeros?
Sure, for example, in kernel/timer.c.
static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
It doesn't seem too popular at this point tho.
Thanks.
--
tejun
prev parent reply other threads:[~2010-10-26 14:57 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-25 22:41 [PATCH] MN10300: Fix the PERCPU() alignment to allow for workqueues David Howells
2010-10-26 9:10 ` Tejun Heo
2010-10-26 10:22 ` David Howells
2010-10-26 12:14 ` Tejun Heo
2010-10-26 12:27 ` Tejun Heo
2010-10-26 12:45 ` [PATCH] x86, percpu: revert commit fe8e0c25 Tejun Heo
2010-10-26 13:25 ` Ingo Molnar
2010-10-26 13:34 ` Tejun Heo
2010-10-26 13:49 ` Brian Gerst
2010-10-26 15:08 ` Linus Torvalds
2010-10-27 5:43 ` [PATCH] x86-32: Allocate irq stacks seperate from percpu area Brian Gerst
2010-10-27 6:07 ` Eric Dumazet
2010-10-27 9:57 ` Peter Zijlstra
2010-10-27 13:33 ` Eric Dumazet
2010-10-27 13:42 ` Tejun Heo
2010-10-27 13:57 ` Eric Dumazet
2010-10-27 14:00 ` Tejun Heo
2010-10-27 14:24 ` Eric Dumazet
2010-10-27 14:39 ` Tejun Heo
2010-10-27 14:39 ` Eric Dumazet
2010-10-27 14:43 ` Tejun Heo
2010-10-27 15:21 ` Eric Dumazet
2010-10-27 15:35 ` Tejun Heo
2010-10-27 16:07 ` Eric Dumazet
2010-10-27 17:33 ` [PATCH] numa: fix slab_node(MPOL_BIND) Eric Dumazet
2010-10-28 15:59 ` Linus Torvalds
2010-10-28 16:27 ` Eric Dumazet
2010-10-28 16:45 ` Mel Gorman
2010-10-28 16:55 ` Christoph Lameter
2010-10-28 21:07 ` Andrew Morton
2010-10-29 14:55 ` Christoph Lameter
2010-10-27 20:55 ` [PATCH] x86-32: Allocate irq stacks seperate from percpu area Eric Dumazet
2010-10-28 12:01 ` Tejun Heo
2010-10-28 12:30 ` Eric Dumazet
2010-10-28 14:40 ` [PATCH] x86-32: NUMA irq stacks allocations Eric Dumazet
2010-10-29 6:43 ` [tip:x86/urgent] x86-32: Restore irq stacks NUMA-aware allocations tip-bot for Eric Dumazet
2010-10-29 18:32 ` Peter Zijlstra
2010-10-29 20:09 ` Cyrill Gorcunov
2010-10-29 20:28 ` Cyrill Gorcunov
2010-10-29 20:53 ` Eric Dumazet
2010-10-29 20:59 ` Cyrill Gorcunov
2010-10-29 20:58 ` Eric Dumazet
2010-10-29 21:21 ` Cyrill Gorcunov
2010-10-27 15:19 ` [PATCH] x86-32: Allocate irq stacks seperate from percpu area Linus Torvalds
2010-10-27 15:30 ` Ingo Molnar
2010-10-27 15:33 ` Ingo Molnar
2010-10-27 15:40 ` Tejun Heo
2010-10-27 15:43 ` Ingo Molnar
2010-10-27 16:03 ` [tip:x86/urgent] " tip-bot for Brian Gerst
2010-10-27 16:04 ` [tip:x86/urgent] percpu: Remove the multi-page alignment facility tip-bot for Ingo Molnar
2010-10-26 14:06 ` [RFC PATCH] percpu: always align percpu output section to PAGE_SIZE Tejun Heo
2011-03-24 6:46 ` [Uclinux-dist-devel] " Mike Frysinger
2011-03-24 8:25 ` Tejun Heo
2011-03-24 8:51 ` Tejun Heo
2011-03-24 13:46 ` Mike Frysinger
2011-03-24 17:51 ` Tejun Heo
2011-03-24 8:54 ` [PATCH UPDATED] " Tejun Heo
2010-10-26 14:50 ` [PATCH] MN10300: Fix the PERCPU() alignment to allow for workqueues David Howells
2010-10-26 14:56 ` Tejun Heo [this message]
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