Re: Kernel Scalability

From: l . genoni
Date: Wed May 02 2007 - 13:40:38 EST



On Wed, 2 May 2007, Daniel J Blueman wrote:

Date: Wed, 2 May 2007 16:43:44 +0100
From: Daniel J Blueman <daniel.blueman@xxxxxxxxx>
To: Rajib Majumder <rajibm2005@xxxxxxxxx>
Cc: Linux Kernel <linux-kernel@xxxxxxxxxxxxxxx>
Subject: Re: Kernel Scalability
Resent-Date: Wed, 02 May 2007 17:44:58 +0200
Resent-From: <l.genoni@xxxxxx>

On 2 May, 14:00, "Rajib Majumder" <rajibm2005@xxxxxxxxx> wrote:
Hi,

I am wondering if 2.4.x/2.6.x kernel is scalable enough to run on
8-CPU hardware. Do we have any scalability comparison data between
2.4/2.6 kernels and beyond 4-CPU?

If yes, is the scalablity is near linear?

Any input is appreciated.

There are 128-processor IA64 systems which run recent 2.6 kernels out
there; the per-processor counters, RCU and page-fault scalability work
has been instrumental to the necessary scaling for decent resource
usage on these.

IIRC, there were some patches being developed to improve pagecache
scalability lately too, but I guess it all depends on what kind of
workload you have...

To stay on systems probably more familiar to the user who asked this question, there are also some 64 core X86_64 bot AMD and Intel out there, here the 2.6 kernel is doing very well even on those intel CPU with shared L2 cache.
I have some 16 and 32 core Opteron and never had scalability problems.
You have to pay a lot of attention to your kernel configuration (100 HZ, just BKL preemption), and to the filesystems you decide to use.


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