From: Yuyang Du <yuyang.du@intel.com>
To: bsegall@google.com
Cc: Morten Rasmussen <morten.rasmussen@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Steve Muckle <steve.muckle@linaro.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>,
"mturquette@baylibre.com" <mturquette@baylibre.com>,
"rjw@rjwysocki.net" <rjw@rjwysocki.net>,
Juri Lelli <Juri.Lelli@arm.com>,
"sgurrappadi@nvidia.com" <sgurrappadi@nvidia.com>,
"pang.xunlei@zte.com.cn" <pang.xunlei@zte.com.cn>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig
Date: Tue, 15 Sep 2015 06:56:42 +0800 [thread overview]
Message-ID: <20150914225642.GB11102@intel.com> (raw)
In-Reply-To: <xm261te0vrav.fsf@sword-of-the-dawn.mtv.corp.google.com>
On Mon, Sep 14, 2015 at 10:34:00AM -0700, bsegall@google.com wrote:
> >> SCHED_LOAD_RESOLUTION and the non-SLR part of SCHED_LOAD_SHIFT are not
> >> required to be the same value and should not be conflated.
> >>
> >> In particular, since cgroups are on the same timeline as tasks and their
> >> shares are not scaled by SCHED_LOAD_SHIFT in any way (but are scaled so
> >> that SCHED_LOAD_RESOLUTION is invisible), changing that part of
> >> SCHED_LOAD_SHIFT would cause issues, since things can assume that nice-0
> >> = 1024. However changing SCHED_LOAD_RESOLUTION would be fine, as that is
> >> an internal value to the kernel.
> >>
> >> In addition, changing the non-SLR part of SCHED_LOAD_SHIFT would require
> >> recomputing all of prio_to_weight/wmult for the new NICE_0_LOAD.
> >
> > I think I follow, but doesn't that mean that the current code is broken
> > too? NICE_0_LOAD changes if you change SCHED_LOAD_RESOLUTION:
> >
> > #define SCHED_LOAD_SHIFT (10 + SCHED_LOAD_RESOLUTION)
> > #define SCHED_LOAD_SCALE (1L << SCHED_LOAD_SHIFT)
> >
> > #define NICE_0_LOAD SCHED_LOAD_SCALE
> > #define NICE_0_SHIFT SCHED_LOAD_SHIFT
> >
> > To me it sounds like we need to define it the other way around:
> >
> > #define NICE_0_SHIFT 10
> > #define NICE_0_LOAD (1L << NICE_0_SHIFT)
> >
> > and then add any additional resolution bits from there to ensure that
> > NICE_0_LOAD and the prio_to_weight/wmult tables are unchanged.
>
> No, NICE_0_LOAD is supposed to be scale_load(prio_to_weight[nice_0]),
> ie including SLR. It has never been clear to me what
> SCHED_LOAD_SCALE/SCHED_LOAD_SHIFT were for as opposed to NICE_0_LOAD,
> and the new utilization uses of it are entirely unlinked to 1024 == NICE_0
Presume your SLR means SCHED_LOAD_RESOLUTION:
1) The introduction of (not redefinition of) SCHED_RESOLUTION_SHIFT does not
change anything after macro expansion.
2) The constants in prio_to_weight[] and prio_to_wmult[] are tied to a
resolution of 10bits NICE_0, i.e., 1024, I guest it is the user visible
part you mentioned, so is the cgroup share.
To me, it is all ok. With the SCHED_RESOLUTION_SHIFT, the basic resolution
unit, it is just for us to state clearly, the NICE_0's weight has a fixed
resolution of SCHED_RESOLUTION_SHIFT, or even add this:
#if prio_to_weight[20] != 1 << SCHED_RESOLUTION_SHIFT
error "NICE_0 weight not calibrated"
#endif
/* I can learn, Peter */
I guess you are saying we are conflating NICE_0 with NICE_0_LOAD. But to me,
they are just integer metrics, needing a resolution respectively. That is it.
next prev parent reply other threads:[~2015-09-15 6:46 UTC|newest]
Thread overview: 97+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-14 16:23 [PATCH 0/6] sched/fair: Compute capacity invariant load/utilization tracking Morten Rasmussen
2015-08-14 16:23 ` [PATCH 1/6] sched/fair: Make load tracking frequency scale-invariant Morten Rasmussen
2015-09-13 11:03 ` [tip:sched/core] " tip-bot for Dietmar Eggemann
2015-08-14 16:23 ` [PATCH 2/6] sched/fair: Convert arch_scale_cpu_capacity() from weak function to #define Morten Rasmussen
2015-09-02 9:31 ` Vincent Guittot
2015-09-02 12:41 ` Vincent Guittot
2015-09-03 19:58 ` Dietmar Eggemann
2015-09-04 7:26 ` Vincent Guittot
2015-09-07 13:25 ` Dietmar Eggemann
2015-09-11 13:21 ` Dietmar Eggemann
2015-09-11 14:45 ` Vincent Guittot
2015-09-13 11:03 ` [tip:sched/core] " tip-bot for Morten Rasmussen
2015-08-14 16:23 ` [PATCH 3/6] sched/fair: Make utilization tracking cpu scale-invariant Morten Rasmussen
2015-08-14 23:04 ` Dietmar Eggemann
2015-09-04 7:52 ` Vincent Guittot
2015-09-13 11:04 ` [tip:sched/core] sched/fair: Make utilization tracking CPU scale-invariant tip-bot for Dietmar Eggemann
2015-08-14 16:23 ` [PATCH 4/6] sched/fair: Name utilization related data and functions consistently Morten Rasmussen
2015-09-04 9:08 ` Vincent Guittot
2015-09-11 16:35 ` Dietmar Eggemann
2015-09-13 11:04 ` [tip:sched/core] " tip-bot for Dietmar Eggemann
2015-08-14 16:23 ` [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen
2015-09-03 23:51 ` Steve Muckle
2015-09-07 15:37 ` Dietmar Eggemann
2015-09-07 16:21 ` Vincent Guittot
2015-09-07 18:54 ` Dietmar Eggemann
2015-09-07 19:47 ` Peter Zijlstra
2015-09-08 12:47 ` Dietmar Eggemann
2015-09-08 7:22 ` Vincent Guittot
2015-09-08 12:26 ` Peter Zijlstra
2015-09-08 12:52 ` Peter Zijlstra
2015-09-08 14:06 ` Vincent Guittot
2015-09-08 14:35 ` Morten Rasmussen
2015-09-08 14:40 ` Vincent Guittot
2015-09-08 14:31 ` Morten Rasmussen
2015-09-08 15:33 ` Peter Zijlstra
2015-09-09 22:23 ` bsegall
2015-09-10 11:06 ` Morten Rasmussen
2015-09-10 11:11 ` Vincent Guittot
2015-09-10 12:10 ` Morten Rasmussen
2015-09-11 0:50 ` Yuyang Du
2015-09-10 17:23 ` bsegall
2015-09-08 16:53 ` Morten Rasmussen
2015-09-09 9:43 ` Peter Zijlstra
2015-09-09 9:45 ` Peter Zijlstra
2015-09-09 11:13 ` Morten Rasmussen
2015-09-11 17:22 ` Morten Rasmussen
2015-09-17 9:51 ` Peter Zijlstra
2015-09-17 10:38 ` Peter Zijlstra
2015-09-21 1:16 ` Yuyang Du
2015-09-21 17:30 ` bsegall
2015-09-21 23:39 ` Yuyang Du
2015-09-22 17:18 ` bsegall
2015-09-22 23:22 ` Yuyang Du
2015-09-23 16:54 ` bsegall
2015-09-24 0:22 ` Yuyang Du
2015-09-30 12:52 ` Peter Zijlstra
2015-09-11 7:46 ` Leo Yan
2015-09-11 10:02 ` Morten Rasmussen
2015-09-11 14:11 ` Leo Yan
2015-09-09 19:07 ` Yuyang Du
2015-09-10 10:06 ` Peter Zijlstra
2015-09-08 13:39 ` Vincent Guittot
2015-09-08 14:10 ` Peter Zijlstra
2015-09-08 15:17 ` Vincent Guittot
2015-09-08 12:50 ` Dietmar Eggemann
2015-09-08 14:01 ` Vincent Guittot
2015-09-08 14:27 ` Dietmar Eggemann
2015-09-09 20:15 ` Yuyang Du
2015-09-10 10:07 ` Peter Zijlstra
2015-09-11 0:28 ` Yuyang Du
2015-09-11 10:31 ` Morten Rasmussen
2015-09-11 17:05 ` bsegall
2015-09-11 18:24 ` Yuyang Du
2015-09-14 17:36 ` bsegall
2015-09-14 12:56 ` Morten Rasmussen
2015-09-14 17:34 ` bsegall
2015-09-14 22:56 ` Yuyang Du [this message]
2015-09-15 17:11 ` bsegall
2015-09-15 18:39 ` Yuyang Du
2015-09-16 17:06 ` bsegall
2015-09-17 2:31 ` Yuyang Du
2015-09-15 8:43 ` Morten Rasmussen
2015-09-16 15:36 ` Peter Zijlstra
2015-09-08 11:44 ` Peter Zijlstra
2015-09-13 11:04 ` [tip:sched/core] " tip-bot for Dietmar Eggemann
2015-08-14 16:23 ` [PATCH 6/6] sched/fair: Initialize task load and utilization before placing task on rq Morten Rasmussen
2015-09-13 11:05 ` [tip:sched/core] " tip-bot for Morten Rasmussen
2015-08-16 20:46 ` [PATCH 0/6] sched/fair: Compute capacity invariant load/utilization tracking Peter Zijlstra
2015-08-17 11:29 ` Morten Rasmussen
2015-08-17 11:48 ` Peter Zijlstra
2015-08-31 9:24 ` Peter Zijlstra
2015-09-02 9:51 ` Dietmar Eggemann
2015-09-07 12:42 ` Peter Zijlstra
2015-09-07 13:21 ` Peter Zijlstra
2015-09-07 13:23 ` Peter Zijlstra
2015-09-07 14:44 ` Dietmar Eggemann
2015-09-13 11:06 ` [tip:sched/core] sched/fair: Defer calling scaling functions tip-bot for Dietmar Eggemann
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