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SubjectRe: xmm2 - monitor Linux MM active/inactive lists graphically
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Linus Torvalds <torvalds@transmeta.com> writes:

> On 25 Oct 2001, Zlatko Calusic wrote:
> >
> > Sure. Output of 'vmstat 1' follows:
> >
> > 1 0 0 0 254552 5120 183476 0 0 12 24 178 438 2 37 60
> > 0 1 0 0 137296 5232 297760 0 0 4 5284 195 440 3 43 54
> > 1 0 0 0 126520 5244 308260 0 0 0 10588 215 230 0 3 96
> > 0 2 0 0 117488 5252 317064 0 0 0 8796 176 139 1 3 96
> > 0 2 0 0 107556 5264 326744 0 0 0 9704 174 78 0 3 97
>
> This does not look like a VM issue at all - at this point you're already
> getting only 10MB/s, yet the VM isn't even involved (there's definitely no
> VM pressure here).

That's true, I'll admit. Anyway, -ac kernels don't have the problem,
and I was misleaded by the fact that only VM implementation differs in
those two branches (at least I think so).

>
> > Notice how there's planty of RAM. I'm writing sequentially to a file
> > on the ext2 filesystem. The disk I'm writing on is a 7200rpm IDE,
> > capable of ~ 22 MB/s and I'm still getting only ~ 9 MB/s. Weird!
>
> Are you sure you haven't lost some DMA setting or something?
>

No. Setup is fine. I wouldn't make such a mistake. :)
If the disk were in some PIO mode, CPU usage would be much higher, but
it isn't.

This all definitely looks like a problem either in the bdflush daemon,
or request queue/elevator, but unfortunately I don't have enough
knowledge of that areas to pinpoint it more precisely.
--
Zlatko
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