Re: [PATCH] Recent VM fiasco - fixed

Zlatko Calusic
2000-05-10T11:50:47Z

Christoph Rohland <cr@sap.com> writes:

> Linus Torvalds <torvalds@transmeta.com> writes:
>
> > On 9 May 2000, Christoph Rohland wrote:
> >
> > > Linus Torvalds <torvalds@transmeta.com> writes:
> > >
> > > > Try out the really recent one - pre7-8. So far it hassome good reviews,
> > > > and I've tested it both on a 20MB machine and a 512MB one..
>
> > > I append the mem and task info from sysrq. Mem info seems to not
> > > change after lockup.
> >
> > I suspect that if you do right-alt + scrolllock, you'll see it looping on
> > a spinlock. Which is why the memory info isn't changing ;)
> >
> > But I'll double-check the shm code (I didn't test anything that did any
> > shared memory, for example).
>
> Juan Quintela's patch fixes the lockup. shm paging locked up on the
> page lock.
>
> Now I can give more data about pre7-8. After a short run I can say the
> following:
>
> The machine seems to be stable, but VM is mainly unbalanced:
>
> [root@ls3016 /root]# vmstat 5
> procs memory swap io system cpu
> r b w swpd free buff cache si so bi bo in cs us sy id
>
> [...]
>
> 9 3 0 0 1460016 1588 11284 0 0 0 0 109 23524 4 96 0
> 9 3 1 7552 557432 1004 19320 0 1607 0 402 186 42582 2 89 9
> 11 1 1 41972 111368 424 53740 0 6884 2 1721 277 25904 0 89 10
[ too many lines error, truncating... ]
> 9 2 1 46536 627356 116 31072 87 8675 23 2169 1784 1412 0 96 4
> 10 0 1 46664 617368 116 31200 0 26 0 6 258 112 0 100 0
> 10 0 1 47300 607184 116 31832 0 126 0 32 291 110 0 100 0
>
> So we are swapping out with lots of free memory and killing random
> processes. The machine also becomes quite unresponsive compared to
> pre4 on the same tests.
>

I'll second this!

I checked pre7-8 briefly, but I/O & MM interaction is bad. Lots of
swapping, lots of wasted CPU cycles and lots of dead writer processes
(write(2): out of memory, while there is 100MB in the page cache).

Back to my patch and working on the solution for the 20-24 MB & 1GB
machines. Anybody with spare 1GB RAM to help development? :)

--
Zlatko