Re: Direct io on block device has performance regression on 2.6.xkernel

From: David Lang
Date: Wed Mar 09 2005 - 23:25:02 EST

On Wed, 9 Mar 2005, Andrew Morton wrote:

David Lang <dlang@xxxxxxxxxxxxxxxxxx> wrote:

(I've seen a 50%
performance hit on 2.4 with just a thousand or two threads compared to

Was that 2.4 kernel a vendor kernel with the O(1) scheduler?

no, a 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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