From: Andrew Theurer <habanero@us.ibm.com>
To: Erich Focht <efocht@hpce.nec.com>, Andi Kleen <ak@muc.de>, mingo@elte.hu
Subject: Re: [patch 2.6.0t4] 1 cpu/node scheduler fix
Date: Mon, 25 Aug 2003 10:54:36 -0500
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Cc: linux-kernel <linux-kernel@vger.kernel.org>,
       LSE <lse-tech@lists.sourceforge.net>,
       "Martin J. Bligh" <mbligh@aracnet.com>, torvalds@osdl.org
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> This simple patch is not meant as opposition to Andrew's attempt to
> NUMAize the whole scheduler. That one will definitely make NUMA
> coders' lives easier but I fear that it is a bit too complex for
> 2.6. 

I would agree, it's probably too much to change this late in 2.6.  Eventually 
(2.7) I think we should revisit this and try for a more unified approach.  

> The attached small incremental change is sufficient to solve the
> main problem. Besides, the change of the cross-node scheduling is
> compatible with Andrew's scheduler structure. I really don't like the
> timer-based cross-node balancing because it is too unflexible (no way
> to have different balancing intervals for each node) and I'd really
> like to get back to just one single point of entry for load balancing:
> the routine load_balance(), no matter whether we balance inside a
> timer interrupt or while the CPU is going idle.

Looks good to me.  One other thing your patch fixes:  Once in a while we 
called load_balance in rebalance_tick with the wrong 'idle' value.  
Occasionally we would be on an idle_node and idle_cpu rebalance tick, the 
idle cpu would [possibly] pull a task, become non-idle, then we would call 
load_balance again, but still have idle=1 for the intranode balance.  

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