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SubjectRe: What version of the kernel fixes these VM issues?

On Fri, 24 Aug 2001, Daniel Phillips wrote:

> On August 24, 2001 10:47 am, Anwar P wrote:
> > We have big system (8 processors, 8GB ram), running Oracle and this other
> > ETL tool. Oracle is up and running all the time, and the ETL tool runs
> > once a day. But everytime the ETL tool runs (along with Oracle), the
> > system seems to run out of memory, and the server comes to a crawl, often
> > with keyborad response in 10 to 15 minute intervals. We are currently
> > using the 2.4.3-6 kernel that comes with Redhat 7.1.
> >
> > We know that Oracle comsumes no more than 2GB of memory at peak usage, and
> > the ETL tool itself consumes less than 1GB. But the ETL tool does process
> > a whole bunch of text files (total about 6GB worth of), and it runs for
> > about 2 hours. What happens is that while they are both running, the
> > filesystem cache size increases progressively, and some time later, it
> > begins swapping. We do have 16GB (2x RAM) of swap. And when it starts to
> > swap, the server responds to keystrokes/commands randomly and appears dead
> > for 10s of minutes. We know that together our applications do not need more
> > than 4GB of RAM on this 8GB box, so it is the VM that is causing this
> > unnecessary swapping by trying to use too much memory for filesystem cache.
> There is no way your system should be going into swap under these conditions
> - it's a bug. We have probably fixed this already.
> Please try 2.4.9 and 2.4.8-ac10. If the system slows down, look in your logs
> and see if there are any "allocation failed" messages. Use top or do watch
> cat /proc/meminfo to be sure your system isn't going into swap, and please
> let us know what happens.

I have a totally different setup but I can reproduce the same behavior on
the system I have here:

ARM board with 32 MB RAM, no flash, NFS root.
The kernel is based on 2.4.8-ac9 plus some small VM fixes from -ac10.

My test consist in compiling gcc 3.0 while some MP3s are continously playing
in the background. The gcc build goes pretty far along until both the mp3
player and the gcc build completely jam. Oh maybe not completely as I get
about 100ms of audio playing every 10 secs. bash starts echoing what I type
one char per approx 5 sec. The only thing that still works fine is the
magic sysrq that clearly shows that the CPU is spinning in the VM code. NFS
trafic is also going on full bandwidth but no progress ever happens in user

My console is on a serial port so if someone can send me a patch with
whatever printks to trace what's happening in real time I'll be glad to
provide the trace file. Reaching the jam state takes about 5 minutes so
it's not hard to reproduce.


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