Re: Possible dcache BUG

[Gene Heskett]

On Wednesday 11 August 2004 21:26, Nick Piggin wrote:
>Gene Heskett wrote:
>>On Wednesday 11 August 2004 01:15, Linus Torvalds wrote:
>>>On Tue, 10 Aug 2004, Linus Torvalds wrote:
>>>>So I suspect it's a balancing issue. Possibly just the slight
>>>>change in slab balancing to fix the highmem problems. Maybe we
>>>>shrink slab _too_ aggressively or something.
>>>
>>>Udo, that's a simple thing to check. If it's the slab balancing
>>>changes, then you should be able to test it with just a
>>>
>>>	bk cset -x1.1830.4.3
>>>
>>>if you have the current BK and are a BK user, or by just revertign
>>>the patch here ("patch -R -p1" from inside your linux source tree)
>>>if you're not a BK user..
>>>
>>>		Linus
>>
>>With the previously attached patch reverted, a fresh kernel builds
>> in: real    7m18.296s
>>user    5m49.385s
>>sys     0m31.760s
>>which is a marked improvement, but still about 1m30 or so slow.
>
>This could easily be from too much slab pressure. How much memory do
> you have?

1 Gb in 2 512Mb sticks of DDR400 ram which signs on in the bios as 
dual channel.  The sticks are in the first and third slots as 
recommended by the mobo docs.

>Have you got highmem turned on?
Yes

>The new slab pressure calculation is an improvement in that it won't
> let slab
>get out of control and cause OOMs, however it can shrink the slab
> too much. If you regularly need ZONE_DMA pages, for example. AFAIKS
> there isn't much you
>can do about this except go to per-zone slab LRUs.

And how would an otherwise clueless user like me determine that?

>That said, your stability problems should be resolved first. If they
> are fixed,

Which as yet is an unknown, Nick.  Uptime now at
 22:15:14 up 12:30,  5 users,  load average: 1.03, 1.11, 1.05

>and you would like to help track down the slowdown, run the kernel
>compile about
>3 times each with and without the patch, and save cat /proc/vmstat
>before and
>after each compile. Try to keep all else constant.

I'll try that if I get to a 30+ hour uptime.

>Thanks
>Nick

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
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by Gene Heskett are:
Copyright 2004 by Maurice Eugene Heskett, all rights reserved.
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