Message-ID: <4199550E.1030704@cyberone.com.au>
Date: Tue, 16 Nov 2004 12:17:02 +1100
From: Nick Piggin <piggin@cyberone.com.au>
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To: Darren Hart <dvhltc@us.ibm.com>
CC: linux-kernel@vger.kernel.org, Matt Dobson <colpatch@us.ibm.com>,
       Martin J Bligh <mbligh@aracnet.com>,
       Rick Lindsley <ricklind@us.ibm.com>, Andrew Morton <akpm@osdl.org>,
       Ingo Molnar <mingo@elte.hu>
Subject: Re: [patch] scheduler: rebalance_tick interval update
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Darren Hart wrote:

>The current rebalance_tick() code assigns each sched_domain's
>last_balance field to += interval after performing a load_balance.  If
>interval is 10, this has the effect of saying:  we want to run
>load_balance at time = 10, 20, 30, 40, etc...  If for example
>last_balance=10 and for some reason rebalance_tick can't be run until
>30, load_balance will be called and last_balance will be updated to 20,
>causing it to call load_balance again immediately the next time it is
>called since the interval is 10 and we are already at >30.  It seems to
>me that it would make much more sense for last_balance to be assigned
>jiffies after a load_balance, then the meaning of last_balance is more
>exact: "this domain was last balanced at jiffies" rather than "we last
>handled the balance we were supposed to do at 20, at some indeterminate
>time".  The following patch makes this change.
>
>

Hi Darren,

This is how I first implemented it... but I think this will cause
rebalance points of each processor to tend to become synchronised
(rather than staggered) as ticks get lost.

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