Messages in this thread | | | Subject | Re: [PATCH] sched: balance_cpu to consider other cpus in its group as target of (pinned) task migration | From | Peter Zijlstra <> | Date | Mon, 04 Jun 2012 13:49:47 +0200 |
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On Mon, 2012-06-04 at 17:11 +0530, Srivatsa Vaddagiri wrote: > * Peter Zijlstra <peterz@infradead.org> [2012-06-04 11:00:54]: > > > > Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> > > > > Did vatsa write this patch? > > I wrote the first version of the patch which Prashanth took, tested, > fixed a bug and is finally publishing it. So yes, > > > If so, you forgot a From header, if not, wtf!? > > it is missing the From header. > > > OK, so previously we only pulled to ourselves, > > That't not entirely true isn't it i.e this_cpu need not equal > smp_processor_id even before this change.
You forgot to finish that, I presume you were thinking of nohz idle balancing? True, but in that case the target was at least idle.
> > now you make cpu x move > > from cpu y to cpu z. This changes the dynamic of the load-balancer, not > > a single word on that and its impact/ramifications. > > The other possibility is for the right sibling cpus to do load balance > in the same domain (noting that it needs to pull a task from another > sched_group to itself and ignoring balance_cpu). That seemed like a more > invasive change than this patch. We'd be happy to try any other approach > you have in mind.
I'm not saying the approach is bad, I'm just saying the patch is bad. Mostly because there's a distinct lack of information on things.
There's nothing to indicate you've considered stuff, found this the best solution because of other stuff etc... thus I think its the first thing that came to mind without due consideration.
I don't like unconsidered poking at the load-balancer.
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