Re: long stalls

[Brian Tinsley <btinsley@emageon.com>]

Thanks for the reply!

I thought highmem I/O was addressed in 2.4.20? Am I off-base here?

I actually just built a 2.4.20 kernel with highmem debugging turned on. 
We'll see if anything pops up.


Brian Gerst wrote:

> 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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-[========================]-
-[      Brian Tinsley     ]-
-[ Chief Systems Engineer ]-
-[        Emageon         ]-
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