Re: [lockup] Re: objrmap-core-1 (rmap removal for file mappings to avoid 4:4 in <=16G machines)

Andrea Arcangeli
2004-03-09T16:38:30Z

On Tue, Mar 09, 2004 at 05:07:09PM +0100, Ingo Molnar wrote:
>
> * Andrea Arcangeli <andrea@suse.de> wrote:
>
> > > or run the attached test-mmap2.c code, which simulates a very small DB
> > > app using only 1800 vmas per process: it only maps 8 MB of shm and
> > > spawns 32 processes. This has an even more lethal effect than the
> > > previous code.
> >
> > this use more cpu than the previous one, but no other differences.
>
> how fast is the system you tried this on? If it's faster than the 500

xeon 4-way 2.5ghz

> MHz box i tried it on then please try the attached test-mmap3.c. (which
> is still not doing anything extreme.)

it's not attached, but I guess I can hack the mmap2 myself too by just
increasing the number of tasks and number of mmaps ;).

But before doing more tests I think I will finish my anon_vma work and
the objrmap optimizations, then I can concentrante on the testing. At
the moment we already know various bits that can be optimized, so I
prefer to get those implemented first.

another important thing is that we've a reschedule point for every
different page we unmap, not sure if it's the case right now (I didn't
concentrate much on the callers yet).