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From: Nick Piggin <piggin@cyberone.com.au>
To: Guillaume Chazarain <guichaz@yahoo.fr>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH]O18.1int
Date: Thu, 28 Aug 2003 23:58:29 +1000	[thread overview]
Message-ID: <3F4E0A85.1040208@cyberone.com.au> (raw)
In-Reply-To: <A00409NJIDDBTRJI86KG96C8BZX3VHF.3f4e071c@monpc>



Guillaume Chazarain wrote:

>28/08/03 14:34:15, Nick Piggin <piggin@cyberone.com.au> wrote:
>
>>Guillaume Chazarain wrote:
>>
>>
>>>Hi Con (and linux-kernel),
>>>
>>>I noticed a regression wrt 2.6.0-test4 and 2.4.22 with this
>>>big context-switcher:
>>>
>>>
>>Hi Guillaume,
>>If you get the time, would you be able to try my patch? Thanks.
>>
>
>Here are the results for Nick's v8:
>
>top(1):
>
>  639 g         30   0  1336  260 1308 R 51.2  0.1   0:03.80 a.out
>  638 g         22   0  1336  260 1308 S 47.3  0.1   0:03.39 a.out
>
>User time (seconds): 0.57
>System time (seconds): 2.72
>Elapsed (wall clock) time (h:mm:ss or m:ss): 0:06.85
>Minor (reclaiming a frame) page faults: 17
>
>

Thanks Guillaume, so not very good. Its interesting that there can
be such a big difference in performance, but its a very simple app
so makes a good test for the specific regression.

In both Con's and my patches, the reader gets a bit more CPU. This
might be due to it preempting the writer more often on wakeups,
which would lead to more scheduling per work done and a regression.

If this is the case, I'm not sure the behaviour is too undesirable
though: its often very important for woken processes to be run
quickly. Its not clear that this workload is something we would
want to optimize for. Assuming the problem is what I guess.

I will take a look into it further when I get time tomorrow.



  reply	other threads:[~2003-08-28 13:58 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-08-28 13:43 [PATCH]O18.1int Guillaume Chazarain
2003-08-28 13:58 ` Nick Piggin [this message]
  -- strict thread matches above, loose matches on Subject: below --
2003-08-28 12:23 [PATCH]O18.1int Guillaume Chazarain
2003-08-23 22:03 [PATCH]O18.1int Voluspa
2003-08-24  4:04 ` [PATCH]O18.1int Con Kolivas
2003-08-23  5:55 [PATCH]O18.1int Con Kolivas
2003-08-23  9:08 ` [PATCH]O18.1int Thomas Schlichter
2003-08-23  9:18   ` [PATCH]O18.1int Nick Piggin
2003-08-23 12:22     ` [PATCH]O18.1int Con Kolivas
2003-08-23 12:21   ` [PATCH]O18.1int Con Kolivas
2003-08-23  9:32 ` [PATCH]O18.1int Andrew Morton
2003-08-23  9:49   ` [PATCH]O18.1int Nick Piggin
2003-08-23 16:58     ` [PATCH]O18.1int Con Kolivas
2003-08-23 21:49       ` [PATCH]O18.1int Andrew Morton
2003-08-24  2:46         ` [PATCH]O18.1int Con Kolivas
2003-08-23 13:29   ` [PATCH]O18.1int Con Kolivas
2003-08-25  9:24 ` [PATCH]O18.1int Måns Rullgård
2003-08-25  9:42   ` [PATCH]O18.1int Alex Riesen
2003-08-25 10:16     ` [PATCH]O18.1int Con Kolivas
2003-08-25 10:21       ` [PATCH]O18.1int Alex Riesen
2003-08-25 21:02         ` [PATCH]O18.1int Alex Riesen
2003-08-25 22:48           ` [PATCH]O18.1int Con Kolivas
2003-08-25 23:00             ` [PATCH]O18.1int Alex Riesen
2003-08-26 22:03         ` [PATCH]O18.1int Alex Riesen
2003-08-25 10:34       ` [PATCH]O18.1int Måns Rullgård
2003-08-25 10:50         ` [PATCH]O18.1int Con Kolivas
2003-08-25 11:15           ` [PATCH]O18.1int Måns Rullgård
2003-08-25 11:37             ` [PATCH]O18.1int Con Kolivas
2003-08-25 11:58               ` [PATCH]O18.1int Måns Rullgård
2003-08-25 12:28                 ` [PATCH]O18.1int Con Kolivas
2003-08-25 12:49                   ` [PATCH]O18.1int Måns Rullgård
2003-08-25 13:32                     ` [PATCH]O18.1int Con Kolivas
2003-08-25 10:17     ` [PATCH]O18.1int Måns Rullgård
2003-08-25 10:34       ` [PATCH]O18.1int Alex Riesen
2003-08-25 11:23         ` [PATCH]O18.1int Måns Rullgård
2003-08-25 10:48       ` [PATCH]O18.1int Con Kolivas
     [not found]       ` <3F49E482.7030902@cyberone.com.au>
     [not found]         ` <20030825102933.GA14552@Synopsys.COM>
2003-08-26 22:20           ` [PATCH]O18.1int Alex Riesen
2003-08-27  2:26             ` [PATCH]O18.1int Nick Piggin

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