From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Antti P Miettinen <amiettinen@nvidia.com>
Cc: linux-pm@lists.linux-foundation.org
Subject: Re: [PATCH 0/6] RFC: CPU frequency min/max as PM QoS params
Date: Fri, 13 Jan 2012 00:55:35 +0100 [thread overview]
Message-ID: <201201130055.35698.rjw@sisk.pl> (raw)
In-Reply-To: <87ipkhco4h.fsf@amiettinen-lnx.nvidia.com>
On Thursday, January 12, 2012, Antti P Miettinen wrote:
> "Rafael J. Wysocki" <rjw@sisk.pl> writes:
> >> By blocking sleep states we can address "system level latency" or "best case
> >> latency" but as far as I can see PM QoS does not address "worst case
> >> latency".
> >
> > I'm not sure what you mean by "worst case latency".
>
> Umm.. the usual concept. If latency is the time from stimulus to
> response, this time can vary based on context. One part of the context
> is the hardware state but there is also the system load. So for example
> the time from interrupt to display being updated is affected by hardware
> state but also system load. As far as I understand, current PM QoS
> latency requests addresses hardware state but do not account for
> possible resource contention, e.g. several latency sensitive clients
> (device drivers, tasks) competing for CPU. In this sense minimum CPU
> frequency requests would be similar.
That's correct, we don't take possible contention into account in PM QoS,
because such conditions may happen idependently of power management anyway.
Thanks,
Rafael
next prev parent reply other threads:[~2012-01-12 23:55 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-06 0:36 [PATCH 0/6] RFC: CPU frequency min/max as PM QoS params Antti P Miettinen
2012-01-06 0:36 ` [PATCH 1/6] PM QoS: Simplify PM QoS expansion/merge Antti P Miettinen
2012-01-06 15:24 ` mark gross
2012-01-08 23:03 ` Rafael J. Wysocki
2012-01-06 0:36 ` [PATCH 2/6] PM QoS: Add CPU frequency min/max as PM QoS params Antti P Miettinen
2012-01-06 15:30 ` mark gross
2012-01-06 19:32 ` Antti P Miettinen
2012-01-07 3:47 ` mark gross
2012-01-07 8:54 ` Antti P Miettinen
2012-01-06 0:36 ` [PATCH 3/6] cpufreq: Export user_policy min/max Antti P Miettinen
2012-01-06 15:33 ` mark gross
2012-01-06 19:29 ` Antti P Miettinen
2012-01-07 3:53 ` mark gross
2012-01-07 8:47 ` Antti P Miettinen
2012-01-09 14:18 ` mark gross
2012-01-06 0:36 ` [PATCH 4/6] cpufreq: Preserve sysfs min/max request Antti P Miettinen
2012-01-06 0:36 ` [PATCH 5/6] cpufreq: Enforce PM QoS min/max limits Antti P Miettinen
2012-01-06 15:38 ` mark gross
2012-01-06 0:36 ` [PATCH 6/6] input: CPU frequency booster Antti P Miettinen
2012-01-06 15:40 ` mark gross
2012-01-06 15:18 ` [PATCH 0/6] RFC: CPU frequency min/max as PM QoS params mark gross
2012-01-06 15:46 ` mark gross
2012-01-06 19:38 ` Antti P Miettinen
2012-01-07 2:57 ` mark gross
2012-01-06 18:27 ` mark gross
2012-01-08 22:59 ` Rafael J. Wysocki
2012-01-09 14:23 ` mark gross
2012-01-09 21:27 ` Rafael J. Wysocki
2012-01-09 21:57 ` Antti P Miettinen
2012-01-10 20:44 ` Rafael J. Wysocki
2012-01-11 7:26 ` Antti P Miettinen
2012-01-11 23:15 ` Rafael J. Wysocki
2012-01-12 8:37 ` Antti P Miettinen
2012-01-12 23:55 ` Rafael J. Wysocki [this message]
2012-01-10 4:50 ` mark gross
2012-01-10 20:46 ` Rafael J. Wysocki
2012-01-10 21:02 ` Jean Pihet
2012-01-11 7:32 ` Antti P Miettinen
2012-01-11 23:00 ` Rafael J. Wysocki
2012-01-12 8:43 ` Antti P Miettinen
2012-01-13 4:37 ` mark gross
2012-01-12 3:06 ` mark gross
2012-01-12 23:52 ` Rafael J. Wysocki
2012-01-12 3:01 ` mark gross
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