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From: Bill Irwin <bill.irwin@oracle.com>
To: Simon Arlott <simon@fire.lp0.eu>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
akpm@linux-foundation.org, arjan@linux.intel.com
Subject: Re: [PATCH (updated)] timer: Run calc_load halfway through each round_jiffies second
Date: Thu, 1 Mar 2007 15:10:03 -0800 [thread overview]
Message-ID: <20070301231003.GD10643@holomorphy.com> (raw)
In-Reply-To: <45E75911.3070907@simon.arlott.org.uk>
On Thu, Mar 01, 2007 at 10:52:01PM +0000, Simon Arlott wrote:
> Whenever jiffies is started at a multiple of 5*HZ or wraps, calc_load is
> run exactly on the second which is when tasks using round_jiffies will
> be scheduled to run. This has a bad effect on the load average, making
> it tend towards 1.00 if a task happens to run every time the load is
> being calculated.
> This changes calc_load so that it updates load half a second after any
> tasks scheduled using round_jiffies.
> Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Arjan van de Ven <arjan@linux.intel.com>
Well, it doesn't reintroduce the for_each_task() (not that it's present
in similar form) loop in count_active_tasks(), so it doesn't bother me.
You seem to have merely changed some offsets, which resolves the
round_jiffies() clash. It's easy to envision similar degenerate cases,
though I'm not sure we care enough to drop in a PRNG to handle them.
== wli
next prev parent reply other threads:[~2007-03-01 23:10 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-24 15:19 round_jiffies and load average Simon Arlott
2007-03-01 9:11 ` Simon Arlott
2007-03-01 18:52 ` [PATCH] timer: Add an initial 0.5s delay to calc_load Simon Arlott
2007-03-01 22:52 ` [PATCH (updated)] timer: Run calc_load halfway through each round_jiffies second Simon Arlott
2002-01-01 3:05 ` Pavel Machek
2007-03-05 22:35 ` Simon Arlott
2007-03-06 18:42 ` [PATCH (update 4)] " Simon Arlott
2007-03-06 22:20 ` [PATCH (updated)] " Chuck Ebbert
2007-03-01 23:10 ` Bill Irwin [this message]
2007-03-02 10:15 ` [PATCH (update 2)] " Simon Arlott
2007-03-02 15:15 ` [PATCH (update 3)] " Simon Arlott
2007-03-02 16:35 ` Eric Dumazet
2007-03-02 17:32 ` Simon Arlott
2007-03-02 18:03 ` Eric Dumazet
2007-03-02 20:14 ` Simon Arlott
2007-03-02 22:32 ` Eric Dumazet
2007-03-02 23:54 ` Simon Arlott
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