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From: Andrea Arcangeli <andrea@suse.de>
To: Andrew Morton <akpm@osdl.org>
Cc: Nick Piggin <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 06:46:59 +0100	[thread overview]
Message-ID: <20050106054659.GS4597@dualathlon.random> (raw)
In-Reply-To: <20050105213207.721b1aae.akpm@osdl.org>

On Wed, Jan 05, 2005 at 09:32:07PM -0800, Andrew Morton wrote:
> > > The slight improvement you suggested of waiting on _any_ random
> > > PG_writeback to go away (instead of one particular one as I did in 2.4)
> 
> It's a HUGE improvement.

I didn't want to question the improvement in wall clock time terms.

> For the third time: "fixing" this involves delivering a wakeup to all zones
> in the page's classzone in end_page_writeback(), and passing the zone* into
> blk_congestion_wait().  Only deliver the wakeup on every Nth page to get a
> bit of batching and to reduce CPU consumption.  Then demonstrating that the
> change actually improves something.

Since I cannot reproduce oom kills with writeback, I sure can't
demonstrate it on bare hardware with unmodified kernel.

But I dislike code that works by luck, and sure I could demonstrate it
if I bothered to write an artificial testcase on simulated hardware.
This is the only reason I mentioned this bug in the first place, not
because I'm reproducing it.

  reply	other threads:[~2005-01-06  5:46 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 [this message]
2005-01-06  5:59                                         ` Andrew Morton
2005-01-06  6:16                                           ` Andrea Arcangeli
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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