Re: 2.3.12 - klogd 100% CPU && Bogus Buffer memory count

Jim Gettys (jg@pa.dec.com)
Thu, 5 Aug 1999 13:16:44 -0700


I believe this may be a more generic bug than 2.3.12: I've seen
klogd run away on my Alpha DS20 several times (100% CPU) running 2.2.10-ac9.
I haven't thought to run vmstat: I'll try the next time it runs away
and see if it is the same symptom there.

The way I've triggered it is to do parallel makes of the Linux
kernel (pretty process intensive: this system has 2 gig of main memory,
so it doesn't hit the disk particularly hard :-) ).

I've rebuilt klogd debug so if I can trigger it again, I may be able
to figure out where it is looping.

In any case, it seems likely that this bug is not just 2.3.12, but
a more generic SMP related problem.
- Jim Gettys

> Sender: owner-linux-kernel@vger.rutgers.edu
> From: Mofeed Shahin <shahin@labf.org>
> Date: Fri, 6 Aug 1999 04:03:08 +0930 (CST)
> To: linux-kernel@vger.rutgers.edu
> Subject: 2.3.12 - klogd 100% CPU && Bogus Buffer memory count
> -----
> G'day all,
>
> First off I will explain what I was doing that caused the problem.
> I was copying a whole CD to the hard-drive. They are both scsi AIC7xxx.
>
> While I was copying I noticed Xosview not looking too healthy so I ran top
> and noticed that the amount of buffer memory was obviously wrong.
>
> here is the vmstat output :
>
> :vmstat
> procs memory swap io system cpu
> r b w swpd free buff cache si so bi bo in cs us sy id
> 1 0 0 744 2908 4193304 205452 0 0 2 4 52 14 47 0 53
> ^^^^^^^
> Notice the 4.1 GIG of buffer memory.
>
> Also half way through the copy klogd started using up all the CPU time on
> one of the processors.
> Even after the copy had finished klogd was still using up large amounts of
> CPU (100%).
>
> The machine is Dual PIII 450 compiled as SMP with AIC 7xxx SCSI driver.
> With 256 meg ram.
>
> Cheers Mof.
>

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