On Mon, Jan 11, 2021 at 03:36:57PM +0100, Vincent Guittot wrote:
> > >
> > >
> > > I think
> > > that we should decay it periodically to reflect there is less and less
> > > idle time (in fact no more) on this busy CPU that never goes to idle.
> > > If a cpu was idle for a long period but then a
On Fri, 8 Jan 2021 at 20:49, Peter Zijlstra wrote:
>
> On Fri, Jan 08, 2021 at 04:10:51PM +0100, Vincent Guittot wrote:
> > Another thing that worries me, is that we use the avg_idle of the
> > local cpu, which is obviously not idle otherwise it would have been
> > selected, to decide how much
On Fri, 8 Jan 2021 at 20:45, Peter Zijlstra wrote:
>
> On Fri, Jan 08, 2021 at 04:10:51PM +0100, Vincent Guittot wrote:
> > Also, there is another problem (that I'm investigating) which is that
> > this_rq()->avg_idle is stalled when your cpu is busy. Which means that
> > this avg_idle can just
On Fri, 8 Jan 2021 at 17:14, Mel Gorman wrote:
>
> On Fri, Jan 08, 2021 at 04:10:51PM +0100, Vincent Guittot wrote:
> > > > Trying to bias the avg_scan_cost with: loops <<= 2;
> > > > will just make avg_scan_cost lost any kind of meaning because it
> > > > doesn't reflect the avg cost of
On Fri, Jan 08, 2021 at 08:45:44PM +0100, Peter Zijlstra wrote:
> On Fri, Jan 08, 2021 at 04:10:51PM +0100, Vincent Guittot wrote:
> > Also, there is another problem (that I'm investigating) which is that
> > this_rq()->avg_idle is stalled when your cpu is busy. Which means that
> > this avg_idle
On Fri, Jan 08, 2021 at 09:21:48PM +0100, Peter Zijlstra wrote:
> On Fri, Jan 08, 2021 at 10:27:38AM +, Mel Gorman wrote:
>
> > 1. avg_scan_cost is now based on the average scan cost of a rq but
> >avg_idle is still scaled to the domain size. This is a bit problematic
> >because it's
On Fri, Jan 08, 2021 at 10:27:38AM +, Mel Gorman wrote:
> 1. avg_scan_cost is now based on the average scan cost of a rq but
>avg_idle is still scaled to the domain size. This is a bit problematic
>because it's comparing scan cost of a single rq with the estimated
>average idle
On Fri, Jan 08, 2021 at 04:10:51PM +0100, Vincent Guittot wrote:
> Another thing that worries me, is that we use the avg_idle of the
> local cpu, which is obviously not idle otherwise it would have been
> selected, to decide how much time we should spend on looking for
> another idle CPU. I'm not
On Fri, Jan 08, 2021 at 04:10:51PM +0100, Vincent Guittot wrote:
> Also, there is another problem (that I'm investigating) which is that
> this_rq()->avg_idle is stalled when your cpu is busy. Which means that
> this avg_idle can just be a very old and meaningless value. I think
> that we should
On Fri, Jan 08, 2021 at 04:10:51PM +0100, Vincent Guittot wrote:
> > > Trying to bias the avg_scan_cost with: loops <<= 2;
> > > will just make avg_scan_cost lost any kind of meaning because it
> > > doesn't reflect the avg cost of scanning a rq anymore
> > >
> >
> > Before the series, the
On Fri, 8 Jan 2021 at 15:41, Mel Gorman wrote:
>
> On Fri, Jan 08, 2021 at 02:41:19PM +0100, Vincent Guittot wrote:
> > > 1. avg_scan_cost is now based on the average scan cost of a rq but
> > >avg_idle is still scaled to the domain size. This is a bit problematic
> > >because it's
On Fri, Jan 08, 2021 at 02:41:19PM +0100, Vincent Guittot wrote:
> > 1. avg_scan_cost is now based on the average scan cost of a rq but
> >avg_idle is still scaled to the domain size. This is a bit problematic
> >because it's comparing scan cost of a single rq with the estimated
> >
On Fri, Jan 08, 2021 at 01:01:10PM +, Qais Yousef wrote:
> On 01/08/21 10:27, Mel Gorman wrote:
> > for_each_cpu_wrap(cpu, cpus, target) {
> > - if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
> > + if (available_idle_cpu(cpu) || sched_idle_cpu(cpu)) {
> > +
On Fri, 8 Jan 2021 at 11:27, Mel Gorman wrote:
>
> On Tue, Dec 15, 2020 at 08:59:11AM +0100, Peter Zijlstra wrote:
> > On Tue, Dec 15, 2020 at 11:36:35AM +0800, Li, Aubrey wrote:
> > > On 2020/12/15 0:48, Peter Zijlstra wrote:
> > > > We compute the average cost of the total scan, but then use it
On 01/08/21 10:27, Mel Gorman wrote:
> for_each_cpu_wrap(cpu, cpus, target) {
> - if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
> + if (available_idle_cpu(cpu) || sched_idle_cpu(cpu)) {
> + /* Adjust cost of a successful scan */
> +
On Tue, Dec 15, 2020 at 08:59:11AM +0100, Peter Zijlstra wrote:
> On Tue, Dec 15, 2020 at 11:36:35AM +0800, Li, Aubrey wrote:
> > On 2020/12/15 0:48, Peter Zijlstra wrote:
> > > We compute the average cost of the total scan, but then use it as a
> > > per-cpu scan cost when computing the scan
On 2020/12/15 15:59, Peter Zijlstra wrote:
> On Tue, Dec 15, 2020 at 11:36:35AM +0800, Li, Aubrey wrote:
>> On 2020/12/15 0:48, Peter Zijlstra wrote:
>>> We compute the average cost of the total scan, but then use it as a
>>> per-cpu scan cost when computing the scan proportion. Fix this by
>>>
On Tue, Dec 15, 2020 at 08:59:11AM +0100, Peter Zijlstra wrote:
> On Tue, Dec 15, 2020 at 11:36:35AM +0800, Li, Aubrey wrote:
> > On 2020/12/15 0:48, Peter Zijlstra wrote:
> > > We compute the average cost of the total scan, but then use it as a
> > > per-cpu scan cost when computing the scan
On Tue, Dec 15, 2020 at 11:36:35AM +0800, Li, Aubrey wrote:
> On 2020/12/15 0:48, Peter Zijlstra wrote:
> > We compute the average cost of the total scan, but then use it as a
> > per-cpu scan cost when computing the scan proportion. Fix this by
> > properly computing a per-cpu scan cost.
> >
> >
On 2020/12/15 0:48, Peter Zijlstra wrote:
> We compute the average cost of the total scan, but then use it as a
> per-cpu scan cost when computing the scan proportion. Fix this by
> properly computing a per-cpu scan cost.
>
> This also fixes a bug where we would terminate early (!--nr, case) and
We compute the average cost of the total scan, but then use it as a
per-cpu scan cost when computing the scan proportion. Fix this by
properly computing a per-cpu scan cost.
This also fixes a bug where we would terminate early (!--nr, case) and
not account that cost at all.
Signed-off-by: Peter
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