lkml.org 
[lkml]   [2014]   [Jun]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH 02/16] sched: Introduce CONFIG_SCHED_ENERGY
On Tue, Jun 10, 2014 at 12:23:53PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 10, 2014 at 11:06:41AM +0100, Morten Rasmussen wrote:
> > How would you like to disable the energy stuff for users for whom
> > latency is everything?
> >
> > I mean, we are adding some extra load/utilization tracking. While I
> > think we should do everything possible to minimize the overhead, I think
> > it is unrealistic to assume that it will be zero. Is a some extra 'if
> > (energy_enabled)' acceptable?
> >
> > I'm open for other suggestions.
>
> We have the jump-label stuff to do self modifying code ;-) The only
> thing we need to be careful with is data-layout.

Isn't this asking for trouble?

I do get the point of not introducing more make-ifdeffery, but I'm not
so sure the alternative is much better. Do we really want to spend time
tracing down bugs introduced via a self-modifying process in something
as central as the scheduler?

> So I'm _hoping_ we can do all this without more CONFIG knobs, because
> {PREEMPT*SMP*CGROUP^3*NUMA^2} is already entirely annoying to
> build and run test, not to mention that distro builds will have no other
> option than to enable everything anyhow.

True, but if that is the argument, how is adding this as a dynamic thing
any better, you still end up with a test-matrix of the same size?

Building a kernel isn't _that_ much work and it would make the
test-scripts all the much simpler to maintain if we don't have to rely
on some dynamic tweaking of the core.

Just sayin'

--
Henrik Austad


\
 
 \ /
  Last update: 2014-06-10 13:41    [W:0.146 / U:0.408 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site