Re: Maybe a VM bug in 2.4.18-18 from RH 8.0?

Andrew Morton
2002-12-06T07:18:09Z

GrandMasterLee wrote:
>
> On Fri, 2002-12-06 at 00:55, Andrew Morton wrote:
> > Andrea Arcangeli wrote:
> [...]
> > > and you're totally wrong saying that mlocking 700m on a 4G box
> > > could kill it.
> >
> > It is possible to mlock 700M of the normal zone on a 4G -aa kernel.
> > I can't immediately think of anything apart from vma's which will
> > make it fall over, but it will run like crap.
>
> Just curious, but how long would it take a system with 8GB RAM, using 4G
> or 64G kernel to fall over?

A few seconds if you ran the wrong thing. Never if you ran something
else.

> One thing I've noticed, is that 2.4.19aa2
> runs great on a box with 8GB when I don't allocate all that much, but
> seems to run into issues after a large DB has been running on it for
> several days. (i.e. the system get's generally a little slower, less
> responsive, and in some cases crashes after 7 days).

"crashes"? kernel, or application? What additional info is
available?

> Yes, I know, sounds like a memory leak in something, but aside from
> patching Oracle from 8.1.7.4(dba's can't find any new patches ATM), I've
> tried everything except changing my kernel.
>
> Could this be similar behaviour?

No, it's something else. Possibly a leak, possibly vma structures.

You should wait until the machine is sluggish, then capture
the output of:

vmstat 1
cat /proc/meminfo
cat /proc/slabinfo
ps aux