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

Andrea Arcangeli
2004-03-09T16:34:46Z

On Tue, Mar 09, 2004 at 05:10:51PM +0100, Ingo Molnar wrote:
>
> * Andrea Arcangeli <andrea@suse.de> wrote:
>
> > > could you just try test-mmap2.c on such a box, and hit swap?
>
> > Unless it crashes the machine I don't care, it's totally wrong in my
> > opinion to hurt everything useful to save cpu while running an
> > exploit. there are easier ways to waste cpu (rewrite the exploit with
> > truncate please!!!)
>
> i'm not sure i follow. "truncate being slow" is not the same order of
> magnitude of a problem as "the VM being incapable of getting work done".

vm has limits, no matter if with rmap or not, if you ask to map 1
million of vmas on a 64bit arch in the same task the rbtree will
slowdown like a crawl too. The vm is a trade-off, we've to optimize for
good apps.