From: Tim Chen <tim.c.chen@linux.intel.com>
To: Tobias Huschle <huschle@linux.ibm.com>,
Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Ricardo Neri <ricardo.neri@intel.com>,
"Ravi V . Shankar" <ravi.v.shankar@intel.com>,
Ben Segall <bsegall@google.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Len Brown <len.brown@intel.com>, Mel Gorman <mgorman@suse.de>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Steven Rostedt <rostedt@goodmis.org>,
Valentin Schneider <vschneid@redhat.com>,
Ionela Voinescu <ionela.voinescu@arm.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
naveen.n.rao@linux.vnet.ibm.com,
Yicong Yang <yangyicong@hisilicon.com>,
Barry Song <v-songbaohua@oppo.com>, Chen Yu <yu.c.chen@intel.com>,
Hillf Danton <hdanton@sina.com>
Subject: Re: [Patch v3 3/6] sched/fair: Implement prefer sibling imbalance calculation between asymmetric groups
Date: Fri, 14 Jul 2023 16:35:12 -0700 [thread overview]
Message-ID: <1fa026a44ed4d31254396e5ed6cfda1dc68c837d.camel@linux.intel.com> (raw)
In-Reply-To: <b119d88384584e603056cec942c47e14@linux.ibm.com>
On Fri, 2023-07-14 at 16:22 +0200, Tobias Huschle wrote:
>
> >
> > Could this work for case where number of CPU/cores would differ
> > between two sched groups in a sched domain? Such as problem pointed
> > by tobias on S390. It would be nice if this patch can work for that
> > case
> > as well. Ran numbers for a few cases. It looks to work.
> > https://lore.kernel.org/lkml/20230704134024.GV4253@hirez.programming.kicks-ass.net/T/#rb0a7dcd28532cafc24101e1d0aed79e6342e3901
> >
>
>
> Just stumbled upon this patch series as well. In this version it looks
> similar to the prototypes I played around with, but more complete.
> So I'm happy that my understanding of the load balancer was kinda
> correct :)
>
> From a functional perspective this appears to address the issues we saw
> on s390.
Glad that this patch addresses this common issue across architectures.
I did aim to address the asymmetric groups balancing in general.
Peter pointed out this problem that's inherent when he reviewed the first
version of my patchset.
Tim
>
> >
> >
> > > + /* Take advantage of resource in an empty sched group */
> > > + if (imbalance == 0 && local->sum_nr_running == 0 &&
> > > + busiest->sum_nr_running > 1)
> > > + imbalance = 2;
> > > +
> >
> > I don't see how this case would be true. When there are unequal number
> > of cores and local->sum_nr_ruuning
> > is 0, and busiest->sum_nr_running is atleast 2, imbalance will be
> > atleast 1.
> >
> >
> > Reviewed-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
> >
> > > + return imbalance;
> > > +}
> > > +
> > > static inline bool
> > > sched_reduced_capacity(struct rq *rq, struct sched_domain *sd)
> > > {
> > > @@ -10230,14 +10265,12 @@ static inline void
> > > calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
> > > }
> > >
> > > if (busiest->group_weight == 1 || sds->prefer_sibling) {
> > > - unsigned int nr_diff = busiest->sum_nr_running;
> > > /*
> > > * When prefer sibling, evenly spread running tasks on
> > > * groups.
> > > */
> > > env->migration_type = migrate_task;
> > > - lsub_positive(&nr_diff, local->sum_nr_running);
> > > - env->imbalance = nr_diff;
> > > + env->imbalance = sibling_imbalance(env, sds, busiest, local);
> > > } else {
> > >
> > > /*
> > > @@ -10424,7 +10457,7 @@ static struct sched_group
> > > *find_busiest_group(struct lb_env *env)
> > > * group's child domain.
> > > */
> > > if (sds.prefer_sibling && local->group_type == group_has_spare &&
> > > - busiest->sum_nr_running > local->sum_nr_running + 1)
> > > + sibling_imbalance(env, &sds, busiest, local) > 1)
> > > goto force_balance;
> > >
> > > if (busiest->group_type != group_overloaded) {
next prev parent reply other threads:[~2023-07-14 23:36 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-07 22:56 [Patch v3 0/6] Enable Cluster Scheduling for x86 Hybrid CPUs Tim Chen
2023-07-07 22:57 ` [Patch v3 1/6] sched/fair: Determine active load balance for SMT sched groups Tim Chen
2023-07-14 13:06 ` Shrikanth Hegde
2023-07-14 23:05 ` Tim Chen
2023-07-15 18:25 ` Tim Chen
2023-07-16 19:36 ` Shrikanth Hegde
2023-07-17 11:10 ` Peter Zijlstra
2023-07-17 12:18 ` Shrikanth Hegde
2023-07-17 13:37 ` Peter Zijlstra
2023-07-17 14:58 ` [PATCH] sched/fair: Add SMT4 group_smt_balance handling Shrikanth Hegde
2023-07-27 3:11 ` Tim Chen
2023-07-27 13:32 ` Tim Chen
2023-08-07 9:36 ` Shrikanth Hegde
2023-08-21 19:19 ` Tim Chen
2023-09-05 8:03 ` Shrikanth Hegde
2023-09-05 9:49 ` Peter Zijlstra
2023-09-05 18:37 ` Tim Chen
2023-09-06 9:29 ` Shrikanth Hegde
2023-09-06 15:42 ` Tim Chen
2023-09-07 8:58 ` Shrikanth Hegde
2023-09-07 17:42 ` Tim Chen
2023-09-12 10:29 ` [tip: sched/urgent] sched/fair: Fix " tip-bot2 for Tim Chen
2023-09-13 13:11 ` tip-bot2 for Tim Chen
2023-09-05 10:38 ` [PATCH] sched/fair: Add " Peter Zijlstra
2023-09-05 10:41 ` Peter Zijlstra
2023-09-05 17:54 ` Tim Chen
2023-09-06 8:23 ` Peter Zijlstra
2023-09-06 15:45 ` Tim Chen
2023-07-18 6:07 ` [Patch v3 1/6] sched/fair: Determine active load balance for SMT sched groups Tobias Huschle
2023-07-18 14:52 ` Shrikanth Hegde
2023-07-19 8:14 ` Tobias Huschle
2023-07-14 14:53 ` Tobias Huschle
2023-07-14 23:29 ` Tim Chen
2023-07-07 22:57 ` [Patch v3 2/6] sched/topology: Record number of cores in sched group Tim Chen
2023-07-10 20:33 ` Valentin Schneider
2023-07-10 22:13 ` Tim Chen
2023-07-12 9:27 ` Valentin Schneider
2023-07-10 22:40 ` Tim Chen
2023-07-11 11:31 ` Peter Zijlstra
2023-07-11 16:32 ` Tim Chen
2023-07-07 22:57 ` [Patch v3 3/6] sched/fair: Implement prefer sibling imbalance calculation between asymmetric groups Tim Chen
2023-07-14 13:14 ` Shrikanth Hegde
2023-07-14 14:22 ` Tobias Huschle
2023-07-14 23:35 ` Tim Chen [this message]
2023-07-14 20:44 ` Tim Chen
2023-07-14 23:23 ` Tim Chen
2023-07-15 0:11 ` Tim Chen
2023-07-07 22:57 ` [Patch v3 4/6] sched/fair: Consider the idle state of the whole core for load balance Tim Chen
2023-07-14 13:02 ` Shrikanth Hegde
2023-07-14 22:16 ` Tim Chen
2023-07-07 22:57 ` [Patch v3 5/6] sched/x86: Add cluster topology to hybrid CPU Tim Chen
2023-07-08 12:31 ` Peter Zijlstra
2023-07-10 16:13 ` Tim Chen
2023-07-07 22:57 ` [Patch v3 6/6] sched/debug: Dump domains' sched group flags Tim Chen
2023-07-10 20:33 ` Valentin Schneider
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1fa026a44ed4d31254396e5ed6cfda1dc68c837d.camel@linux.intel.com \
--to=tim.c.chen@linux.intel.com \
--cc=bristot@redhat.com \
--cc=bsegall@google.com \
--cc=dietmar.eggemann@arm.com \
--cc=hdanton@sina.com \
--cc=huschle@linux.ibm.com \
--cc=ionela.voinescu@arm.com \
--cc=juri.lelli@redhat.com \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mgorman@suse.de \
--cc=naveen.n.rao@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=rafael.j.wysocki@intel.com \
--cc=ravi.v.shankar@intel.com \
--cc=ricardo.neri@intel.com \
--cc=rostedt@goodmis.org \
--cc=srikar@linux.vnet.ibm.com \
--cc=srinivas.pandruvada@linux.intel.com \
--cc=sshegde@linux.vnet.ibm.com \
--cc=v-songbaohua@oppo.com \
--cc=vincent.guittot@linaro.org \
--cc=vschneid@redhat.com \
--cc=x86@kernel.org \
--cc=yangyicong@hisilicon.com \
--cc=yu.c.chen@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).