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From: Andrea Arcangeli <andrea@suse.de>
To: Andrew Morton <akpm@osdl.org>
Cc: nickpiggin@yahoo.com.au, riel@redhat.com,
	marcelo.tosatti@cyclades.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][5/?] count writeback pages in nr_scanned
Date: Thu, 6 Jan 2005 07:16:08 +0100	[thread overview]
Message-ID: <20050106061608.GU4597@dualathlon.random> (raw)
In-Reply-To: <20050105215909.7ac1f8b1.akpm@osdl.org>

On Wed, Jan 05, 2005 at 09:59:09PM -0800, Andrew Morton wrote:
> But we do need to watch the CPU consumption in there - end_page_writeback()
> already figures fairly high sometimes.

The check for waitqueue_active will avoid all wake_up calls if nobody is
waiting in blk_congestion_wait. Plus it won't need to wakeup on all
classzones, if we have the other side to reigster on all the zones
composing the classzone.

The wakeup is going to be more frequent than the waiter registration.

So we can register the waiter on _all_ the "interested" zones that
composes the classzone, instead of the other way around that you
suggested in the previous email.

That will reduce the wakeup to a single waitqueue_active, and it
shouldn't be too bad.

Same goes for the number of outstanding writebacks, we can collect that
number per zone and have blk_congestion_wait returning immediatly if it
went to zero on all zones composing the classzone after registering.

  reply	other threads:[~2005-01-06  6:16 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-01-03 17:25 [PATCH][5/?] count writeback pages in nr_scanned Rik van Riel
2005-01-05 10:08 ` Andrew Morton
2005-01-05 18:06   ` Andrea Arcangeli
2005-01-05 18:50     ` Rik van Riel
2005-01-05 17:49       ` Marcelo Tosatti
2005-01-05 21:44         ` Andrew Morton
2005-01-05 20:32           ` Marcelo Tosatti
2005-01-05 23:51             ` Nick Piggin
2005-01-06  1:27               ` Rik van Riel
2005-01-06  1:33                 ` Nick Piggin
2005-01-06  1:37                   ` Andrew Morton
2005-01-06  1:40                     ` Nick Piggin
2005-01-06  1:52                       ` Andrea Arcangeli
2005-01-06  1:36                 ` Andrew Morton
2005-01-06  3:42                   ` Rik van Riel
2005-01-06  3:50                     ` Nick Piggin
2005-01-06  4:26                       ` Andrew Morton
2005-01-06  4:35                         ` Nick Piggin
2005-01-06  4:47                           ` Andrew Morton
2005-01-06  4:55                             ` Nick Piggin
2005-01-06  5:03                               ` Andrea Arcangeli
2005-01-06  8:06                               ` Jens Axboe
2005-01-06  8:16                                 ` memory barrier in ll_rw_blk.c (was Re: [PATCH][5/?] count writeback pages in nr_scanned) Nick Piggin
2005-01-06  8:32                                   ` Jens Axboe
2005-01-06  8:53                                     ` Nick Piggin
2005-01-06 12:00                                       ` Jens Axboe
2005-01-06  4:59                             ` [PATCH][5/?] count writeback pages in nr_scanned Andrea Arcangeli
2005-01-06  5:05                               ` Andrew Morton
2005-01-06  5:17                                 ` Andrea Arcangeli
2005-01-06  5:19                                   ` Nick Piggin
2005-01-06  5:25                                     ` Andrea Arcangeli
2005-01-06  5:36                                       ` Nick Piggin
2005-01-06  5:44                                         ` Nick Piggin
2005-01-06  5:37                                       ` Andrew Morton
2005-01-06  5:59                                         ` Andrea Arcangeli
2005-01-06 13:28                                         ` Rik van Riel
2005-01-06  5:32                                     ` Andrew Morton
2005-01-06  5:46                                       ` Andrea Arcangeli
2005-01-06  5:59                                         ` Andrew Morton
2005-01-06  6:16                                           ` Andrea Arcangeli [this message]
2005-01-06  5:06                               ` Nick Piggin
2005-01-06  5:21                                 ` Andrea Arcangeli
2005-01-05 23:26 ` Andrew Morton

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