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From: Andrew Morton <akpm@osdl.org>
To: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Cc: linux-mm@kvack.org, piggin@cyberone.com.au
Subject: Re: [PATCH] kswapd shall not sleep during page shortage
Date: Tue, 9 Nov 2004 18:53:29 -0800	[thread overview]
Message-ID: <20041109185329.35eca4a1.akpm@osdl.org> (raw)
In-Reply-To: <20041109231654.GE8414@logos.cnet>

Marcelo Tosatti <marcelo.tosatti@cyclades.com> wrote:
>
> 
> > And in that case, they may be
> > holding locks whcih prevent kswapd from being able to do any work either.
> 
> OK... Just out of curiosity:
> Isnt the "lock contention" at this level (filesystem) a relatively rare situation? 
> 

It should be relatively rare - most of the blocking opportunities on the
writepage path should be avoided by now - we bale out, try another page,
throttle on some I/O completion if it's all not working out.

There are probably filesystem allocation semaphores.  journal_start/stop
acts as a semaphore, as does get_request_wait().

It all depends on whether you're looking for common case or worst case.  In
page reclaim we should tune for the common case, and avoid deadlocking in
the worst case.
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  parent reply	other threads:[~2004-11-10  2:53 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-11-09 16:46 [PATCH] kswapd shall not sleep during page shortage Marcelo Tosatti
2004-11-09 20:19 ` Andrew Morton
2004-11-09 17:41   ` Marcelo Tosatti
2004-11-09 21:33     ` Andrew Morton
2004-11-09 18:26       ` Marcelo Tosatti
2004-11-09 22:22         ` Andrew Morton
2004-11-09 20:31           ` Marcelo Tosatti
2004-11-10  0:28             ` Andrew Morton
2004-11-09 23:16               ` Marcelo Tosatti
2004-11-09 23:34                 ` Marcelo Tosatti
2004-11-10  2:53                 ` Andrew Morton [this message]
2004-11-10 18:14               ` Marcelo Tosatti
2004-11-10 22:08                 ` Andrew Morton
2004-11-10  0:56           ` Nick Piggin
2004-11-10  2:49             ` Nick Piggin
2004-11-10  2:56               ` Andrew Morton
2004-11-10  3:12                 ` Nick Piggin
2004-11-10  3:18                   ` Andrew Morton
2004-11-10  3:27                     ` Nick Piggin
2004-11-10  4:15                     ` Nick Piggin
2004-11-10  8:17                       ` Marcelo Tosatti

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