Messages in this thread | | | Date | Tue, 13 Jun 2006 04:45:32 -0700 | From | Andrew Morton <> | Subject | Re: 2.6.16-rc6-mm2 |
| |
On Tue, 13 Jun 2006 15:08:40 +1000 Keith Owens <kaos@sgi.com> wrote:
> Andi Kleen (on Tue, 13 Jun 2006 06:56:45 +0200) wrote: > > > >> I have previously suggested a lightweight solution that pins a process > >> to a cpu > > > >That is preempt_disable()/preempt_enable() effectively > >It's also light weight as much as these things can be. > > The difference being that preempt_disable() does not allow the code to > sleep. There are some places where we want to use cpu local data and > the code can tolerate preemption and even sleeping, as long as the > process schedules back on the same cpu.
It would be easy to use this mechanism wrongly:
thread 1 on CPU N thread 2 on CPU N
foo = per_cpu(...) <preempt> foo = per_cpu(...); foo++; per_cpu(...) = foo; <unpreempt> foo++; per_cpu(...) = foo; // whoops
In which scenarios did you envisage it being used? - 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/
| |