Re: [PATCH try 5] CFS: Add hierarchical tree-based penalty.

From: Ingo Molnar
Date: Tue Oct 12 2010 - 05:47:46 EST



* William Pitcock <nenolod@xxxxxxxxxxxxxxxx> wrote:

> Hi,
>
> ----- "Ingo Molnar" <mingo@xxxxxxx> wrote:
>
> > * William Pitcock <nenolod@xxxxxxxxxxxxxxxx> wrote:
> >
> > > Inspired by the recent change to BFS by Con Kolivas, this patch
> > causes
> > > vruntime to be penalized based on parent depth from their root task
> >
> > > group.
> > >
> > > I have, for the moment, decided to make it a default feature since
> > the
> > > design of CFS ensures that broken applications depending on task
> > > enqueue behaviour behaving traditionally will continue to work.
> >
> > Just curious, is this v5 submission a reply to Peter's earlier review
> > of
> > your v3 patch? If yes then please explicitly outline the changes you
> > did
> > so that Peter and others do not have to guess about the direction your
> >
> > work is taking.
>
> I just did that in the email I just sent. Simply put, I was talking
> with Con a few weeks ago about the concept of having a maximum amount
> of service for all threads belonging to a process. This did not work
> out so well, so Con proposed penalizing based on fork depth, which
> still allows us to maintain interactivity with make -j64 running in
> the background.
>
> Actually, I lie: it works great for server scenarios where you have
> some sysadmin also running azureus. Azureus gets penalized instead,
> but other apps like audacious get penalized too.

Thanks for the explanation!

Ingo
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