Messages in this thread | | | Date | Mon, 13 Sep 2010 20:03:48 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH] check_preempt_tick should not compare vruntime with wall time |
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* Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> * Linus Torvalds (torvalds@linux-foundation.org) wrote: > > On Mon, Sep 13, 2010 at 9:16 AM, Mathieu Desnoyers > > <mathieu.desnoyers@efficios.com> wrote: > > > > > > OK, the long IRC discussions we just had convinced me that the current scheme > > > takes things into account by adapting the granularity dynamically, but also got > > > me to notice that check_preempt seems to compare vruntime with wall time, which > > > is utterly incorrect. So maybe all my patch was doing was to expose this bug: > > > > Do you have latency numbers for this patch? > > Sure, see below, > > In addition to this patch, [...]
Note, which is a NOP for your latency workload.
> [...] I also used Peter's approach of reducing the minimum granularity
Ok, that's the very first patch i sent yesterday morning - so we also have my numbers that it reduces latencies.
To move things along i'll apply it with your Reported-by and Acked-by line, ok?
We can also work on the other, more complex things after that, but first lets make some progress on the latency front ...
Thanks,
Ingo
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