iowait

Roman Shterenzon (roman@xpert.com)
Thu, 1 Jul 1999 01:02:23 +0300 (IDDT)


Hello,

I was wondering how is it possible to see the time kernel spends for
waiting for some io to complete.
Something that's called iowait in solaris.
Right now the time spent in system state and the time spent waiting for io
is displayed as "system time".
This is quite critical when you're searching for a bottleneck.
I've browsed mail archives, searched the web as well as the news, but
didn't find any useful information.
No matter what tools I've tried, none of them gave me the time the kernel
spends waiting for io subsystem.
Talking on #linux on EFnet , I was told that this is not implemented in
the kernel.
My question, is it true? and if it is, how hard it this thing to
implement.

P.S. I've seen Andrea Arcangeli's "Linux Interrupt Latency", but this is
not it..

--Roman Shterenzon, System Administrator
[ Xpert UNIX Systems Ltd., Bnei-Brak, Israel. Tel: +972-3-6181118 ]

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