lkml.org 
[lkml]   [2000]   [Oct]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 2.2.18Pre Lan Performance Rocks!

On Mon, 30 Oct 2000, Andi Kleen wrote:

> One problem in Linux 2.2 is that kernel threads reload their VM on
> context switch (that would include the nfsd thread), this should be
> fixed in 2.4 with lazy mm. Hmm actually it should be only fixed for
> true kernel threads that have been started with kernel_thread(), the
> "pseudo kernel threads" like nfsd uses probably do not get that
> optimization because they don't set their MM to init_mm.

yes, but for this there is an explicit mechanizm to lazy-MM during lengthy
system calls, an example is in buffer.c:

user_mm = start_lazy_tlb();
error = sync_old_buffers();
end_lazy_tlb(user_mm);

> > to get disproportiantely higher in Linux than NetWare 5.x and when it hits
> > 60% of total clock cycles, Linux starts dropping off. NetWare 5.x is 1/8
>
> I think that can be explained by the copying.

yes. Constant copying contaminates the L1/L2 caches and creates dirty
cachelines all around the place. Fixed in 2.4 + TUX ;-)

Ingo

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:45    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site