Messages in this thread | | | Date | Tue, 27 Nov 2007 21:28:05 -0800 | From | Andrew Morton <> | Subject | Re: Dynticks Causing High Context Switch Rate in ksoftirqd |
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On Mon, 26 Nov 2007 22:36:17 -0600 Robert Hancock <hancockr@shaw.ca> wrote:
> bdupree@techfinesse.com wrote: > > Question: Why is ksoftirqd eating about 5 to 10 percent of my CPU on an idle > > system? The problem occurs if I config the kernel with tickless > > support (i.e. CONFIG_TICK_ONESHOT=y). (Thanks to "oprofile" for putting me > > onto this.) > > > > I have noted this same problem on kernel versions: 2.6.23.1, 2.6.23.8 and > > 2.6.23.9 > > > > ************************************************************************** > > *** Output from "vmstat -n 1 10" -- Note very high context switch rate *** > > *** This is on a idle machine! *** > > ************************************************************************** > > > > procs -----------memory---------- ---swap-- -----io---- --system-- > > ----cpu---- > > r b swpd free buff cache si so bi bo in cs us sy > > id wa > > 0 0 0 1925556 4768 116104 0 0 124 2 6 7538 1 2 > > 96 1 > > 0 0 0 1925556 4768 116104 0 0 0 0 2 147329 0 1 > > 99 0 > > What did oprofile show? It should be able to narrow down what > function(s) are responsible for the CPU usage..
Sigh. I just asked a similar thing. Let's look at the mail headers:
Message-ID: <41877.67.173.156.207.1196130992.squirrel@www.techfinesse.net> ... From: bdupree@techfinesse.com
From: Robert Hancock <hancockr@shaw.ca> ... In-reply-to: <fa.c70Wy8WHP3DOaDydQ2D94+Xxx/8@ifi.uio.no>
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