Oracle RAC and IRQ Balance

From: Walker, Jed S <Jed_Walker_at_cable.comcast.com>
Date: Mon, 3 Oct 2011 21:29:38 +0000
Message-ID: <BAA6E28B6241F046AED1E62D8697516C55F5A1F1_at_COPDCEXMB09.cable.comcast.com>

Back to my learning of RAC. Today, it was suggested that we turn on IRQBALANCE on our Oracle 11.2.0 RAC systems to help distribute the IRQ load, to hopefully help with performance. I did a check and can see that just one CPU appears to be handling all of these. mpstat -P ALL 2
Linux 2.6.18-53.el5 (node-01) 10/03/2011

09:19:46 PM  CPU   %user   %nice    %sys %iowait    %irq   %soft  %steal   %idle    intr/s
09:19:48 PM  all   14.30    0.00    3.04   23.54    0.25    1.27    0.00   57.59  10903.06
09:19:48 PM    0   41.33    0.00    9.18   40.31    1.02    4.08    0.00    4.08  10902.55
09:19:48 PM    1    2.55    0.00    0.51   14.29    0.00    0.00    0.00   82.65      0.00
09:19:48 PM    2   12.24    0.00    2.04   34.18    0.00    0.00    0.00   52.04      0.00
09:19:48 PM    3    1.02    0.00    0.51    6.63    0.00    0.00    0.00   92.35      0.00

(this is consistent over a period of time)

I then read an article saying that in many cases this doesn't matter - something to do with processes being pinned to a CPU (Sorry, I can't find the article again!).

Does anyone have any experience, or is there a good practice for this and RAC?

service irqbalance start
chkconfig irqbalance on

Thanks,

Jed

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Received on Mon Oct 03 2011 - 16:29:38 CDT