On Thursday 23 February 2006 10:47, Arjan van de Ven wrote:
> On Thu, 2006-02-23 at 10:39 +0100, Andi Kleen wrote:
> > On Thursday 23 February 2006 10:30, Arjan van de Ven wrote:
> > > In a micro-benchmark that stresses the pagefault path, the down_read_trylock
> > > on the mmap_sem showed up quite high on the profile. Turns out this lock is
> > > bouncing between cpus quite a bit and thus is cache-cold a lot. This patch
> > > prefetches the lock (for write) as early as possible (and before some other
> > > somewhat expensive operations). With this patch, the down_read_trylock
> > > basically fell out of the top of profile.
> >
> > It is hard to believe because you effectively didn't do the prefetch
> > very early
>
> all you need is a few dozen cycles though; there's a cr2 move and the
> entire notifier inbetween.... neither of those is really cheap.
Ok. I added that patch.
-Andi
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
