lkml.org 
[lkml]   [2014]   [Mar]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 2/7] sched: rework of sched_domain topology definition

The keyboard deity gave us delete, please apply graciously when replying
to large emails.

On Wed, Mar 19, 2014 at 11:27:12AM +0000, Dietmar Eggemann wrote:
> On 18/03/14 17:56, Vincent Guittot wrote:
> > + if (sd->flags & SD_SHARE_CPUPOWER) {
> > + sd->imbalance_pct = 110;
> > + sd->smt_gain = 1178; /* ~15% */
> > + sd->flags |= arch_sd_sibling_asym_packing();
> > +
> > + } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
> > + sd->imbalance_pct = 117;
> > + sd->cache_nice_tries = 1;
> > + sd->busy_idx = 2;
> > +
> > +#ifdef CONFIG_NUMA
> > + } else if (sd->flags & SD_NUMA) {
> > + sd->cache_nice_tries = 2;
> > + sd->busy_idx = 3;
> > + sd->idle_idx = 2;
> > +
> > + sd->flags |= SD_SERIALIZE;
> > + if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
> > + sd->flags &= ~(SD_BALANCE_EXEC |
> > + SD_BALANCE_FORK |
> > + SD_WAKE_AFFINE);
> > + }
> > +
> > +#endif
> > + } else {
> > + sd->flags |= SD_PREFER_SIBLING;
> > + sd->cache_nice_tries = 1;
> > + sd->busy_idx = 2;
> > + sd->idle_idx = 1;
> > + }
>
> This 'if ... else statement' is still a weak point from the perspective
> of making the code robust:

<snip>

> Is there a way to check that MC and GMC have to have
> SD_SHARE_PKG_RESOURCES set so that this can't happen unnoticed?

So from the core codes perspective those names mean less than nothing.
Its just a string to carry along for us meat-bags. The string isn't even
there when !SCHED_DEBUG.

So from this codes POV you told it it had a domain without PKGSHARE,
that's fine.

That said; yeah the thing isn't the prettiest piece of code. But it has
the big advantage of being the one place where we convert topology into
behaviour.


\
 
 \ /
  Last update: 2014-03-19 14:21    [W:0.209 / U:1.964 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site