From: Andi Kleen <ak@suse.de>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Ravikiran G Thirumalai <kiran@scalex86.org>,
Andi Kleen <ak@suse.de>,
linux-kernel@vger.kernel.org, discuss@x86-64.org,
Andrew Morton <akpm@osdl.org>,
dada1@cosmobay.com
Subject: Re: [patch 3/3] x86_64: Node local pda take 2 -- node local pda allocation
Date: Thu, 15 Dec 2005 10:36:45 +0100 [thread overview]
Message-ID: <20051215093645.GW23384@wotan.suse.de> (raw)
In-Reply-To: <43A127D3.1070106@cosmosbay.com>
> Do you have an idea of the performance gain we could expect from this node
> local pda allocation ?
I wouldn't expect very much.
> Say a CPU is on Node 1, was a change in pda (allocated on Node 0)
> immediatly mirrored on remote node or not ?
The Opteron caches are write back afaik - this means data only leaves
the L2 cache when other data pushes it out.
But the additional traffic on the interconnect was likely negligible.
If anything I would expect the reduced latency when a user space program eat up all
cache and the PDA is needed on the next kernel entry to be helpful.
But it's not very much at least on an Opteron because the NUMA factor
isn't that bad. On Kiran's machines which likely have a higher NUMA
factor I guess it helps more.
-Andi
next prev parent reply other threads:[~2005-12-15 9:36 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-15 2:33 [patch 1/3] x86_64: Node local pda take 2 -- early cpu_to_node Ravikiran G Thirumalai
2005-12-15 2:35 ` [patch 2/3] x86_64: Node local pda take 2 -- cpu_pda_prep Ravikiran G Thirumalai
2005-12-15 2:37 ` [patch 3/3] x86_64: Node local pda take 2 -- node local pda allocation Ravikiran G Thirumalai
2005-12-15 8:22 ` Eric Dumazet
2005-12-15 9:36 ` Andi Kleen [this message]
2005-12-15 9:42 ` [discuss] " Andi Kleen
2005-12-15 18:47 ` Ravikiran G Thirumalai
2005-12-16 0:19 ` Andi Kleen
2005-12-16 3:55 ` Ravikiran G Thirumalai
2005-12-15 9:44 ` [discuss] [patch 1/3] x86_64: Node local pda take 2 -- early cpu_to_node Andi Kleen
2005-12-15 19:01 ` Ravikiran G Thirumalai
2005-12-16 0:20 ` Andi Kleen
2005-12-16 8:11 ` Ravikiran G Thirumalai
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