From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Tejun Heo <htejun@gmail.com>
Cc: zwane@linuxpower.ca, viro@zeniv.linux.org.uk,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH linux-2.6 01/04] brsem: implement big reader semaphore
Date: Sun, 25 Sep 2005 17:19:12 +1000 [thread overview]
Message-ID: <43364F70.7010705@yahoo.com.au> (raw)
In-Reply-To: <20050925064218.FF1C2BEC@htj.dyndns.org>
Tejun Heo wrote:
> 01_brsem_implement_brsem.patch
>
> This patch implements big reader semaphore - a rwsem with very
> cheap reader-side operations and very expensive writer-side
> operations. For details, please read comments at the top of
> kern/brsem.c.
>
This thing looks pretty overengineered. It is difficult to
read with all the little wrapper functions and weird naming
schemes.
What would be wrong with an array of NR_CPUS rwsems? The only
tiny trick you would have to do AFAIKS is have up_read remember
what rwsem down_read took, but that could be returned from
down_read as a token.
I have been meaning to do something like this for mmap_sem to
see what happens to page fault scalability (though the heavy
write-side would make such a scheme unsuitable for mainline).
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2005-09-25 7:18 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-25 6:43 [PATCH linux-2.6 00/04] brsem: [RFC] big reader semaphore Tejun Heo
2005-09-25 6:43 ` [PATCH linux-2.6 01/04] brsem: implement " Tejun Heo
2005-09-25 7:19 ` Nick Piggin [this message]
2005-09-25 8:03 ` Nick Piggin
2005-09-25 8:11 ` Tejun Heo
2005-09-25 8:27 ` Nick Piggin
2005-09-25 8:53 ` Tejun Heo
2005-09-25 9:24 ` Nick Piggin
2005-09-25 10:05 ` Tejun Heo
2005-09-25 11:22 ` Nick Piggin
2005-09-25 6:43 ` [PATCH linux-2.6 02/04] brsem: convert super_block->s_umount to brsem Tejun Heo
2005-09-25 6:43 ` [PATCH linux-2.6 03/04] brsem: fix ro-remount <-> open race condition Tejun Heo
2005-09-25 6:43 ` [PATCH linux-2.6 04/04] brsem: convert cpucontrol to brsem Tejun Heo
2005-09-25 7:39 ` Nick Piggin
2005-09-25 8:03 ` Tejun Heo
2005-09-25 23:46 ` Nathan Lynch
2005-09-26 1:11 ` Nick Piggin
2005-09-26 4:05 ` Tejun Heo
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