Re: long stalls

Brian Gerst (bgerst@didntduck.org)
Tue, 07 Jan 2003 21:44:15 -0500


Brian Tinsley wrote:

> We have been having terrible problems with long stalls, meaning from a
> couple of minutes to an hour, happening when filesystem I/O load gets
> high. The system time as reported by vmstat or sar will increase up to
> 99% and as it spreads to each procesor, the system becomes completely
> unresponsive (except that it responds to pings just fine -
> interesting!). When the system finally returns to the world of the
> living, the only evidence that something bad has happened is the runtime
> for kswapd is abnormally high. I have seen this happen with the stock
> 2.4.17, 2.4.19, and 2.4.20 kernels on SMP PIII and PIV machines (either
> 4GB or 8GB RAM, all SCSI disks, dual GigE NICs). I've searched the lkml
> archives and google and have found several similar postings, but there
> is never an explanation or resolution. Any help would be *very* much
> appreciated! If any info from the system in question is desired, I will
> be glad to provide it.
>
>
>
With 4GB of memory you are likely boucing I/O requests to low memory.
This has been fixed in 2.5. I do not know if a backport exists for 2.4.

--
				Brian Gerst

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