lkml.org 
[lkml]   [2006]   [Mar]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 01/02] cpuset memory spread slab cache filesys
Date
On Wednesday 01 March 2006 21:53, Paul Jackson wrote:
> > > I spent much time minimizing that overhead over the last few months, as
> > > a direct result of your recommendation to do so.
> >
> > IIRC my recommendation only optimized the case of nobody using
> > cpuset if I remember correctly.
>
> As a result of your general concern with the performance impact
> of cpusets on the page allocation code path, I optimized each
> element of it, not just the one case covered by your specific
> recommendation.

Thanks for doing that work then.


>
> > Using a single cpuset would already drop into the slow path, right?
>
> No - having a single cpuset is the fastest path. All tasks
> are in that root cpuset in that case, and all nodes allowed.

Faster than no cpuset?

>
> > I'm not sure I want to get into the business
> > of explaining all the distributions how to set up cpusets ..
>
> Good grief - I already quoted the 3 lines of boottime init script it
> would take - this can't require that much explaining, and your new
> sysctl can't get by with much less:

It would just be on by default - no user space configuration needed.

> And even from the perspective of maintaining Linux, this should be on
> autopilot. Every file systems inode cache is marked, and if we do
> nothing, as more file system types are invented for Linux, they will
> predictably cut+paste the inode slab cache setup from an existing file
> system, and "just get it right."

If something is a good default it shouldn't need user space
configuration at all imho. Only the "weird" cases should.

> I just don't see that it serves any purpose, and I suspect that
> misunderstandings of the performance impact of cpusets are the
> primary source of motivation for such a sysctl.

No that was just one. The other was having good defaults
even on lightweight kernels.

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

\
 
 \ /
  Last update: 2006-03-01 22:02    [W:0.048 / U:1.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site