From: David Lang <david.lang@digitalinsight.com>
To: Andrew Morton <akpm@osdl.org>
Cc: kenneth.w.chen@intel.com, linux-kernel@vger.kernel.org, axboe@suse.de
Date: Wed, 9 Mar 2005 20:15:33 -0800 (PST)
Subject: Re: Direct io on block device has performance regression on 2.6.xkernel
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On Wed, 9 Mar 2005, Andrew Morton wrote:

> David Lang <dlang@digitalinsight.com> wrote:
>>
>> (I've seen a 50%
>>  performance hit on 2.4 with just a thousand or two threads compared to
>>  2.6)
>
> Was that 2.4 kernel a vendor kernel with the O(1) scheduler?

no, a kernel.org kernel. the 2.6 kernel is so much faster for this 
workload that I switched for this app and never looked back. I found that 
if I had 5000 or so idle tasks 2.4 performcane would drop to about a 
quarter of 2.6 (with the CPU system time being the limiting factor)

David Lang

-- 
There are two ways of constructing a software design. One way is to make it so simple that there are obviously no deficiencies. And the other way is to make it so complicated that there are no obvious deficiencies.
  -- C.A.R. Hoare
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