From: Tim Chen <tim.c.chen@linux.intel.com>
To: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>, peterz@infradead.org
Cc: bristot@redhat.com, bsegall@google.com, dietmar.eggemann@arm.com,
hdanton@sina.com, ionela.voinescu@arm.com, juri.lelli@redhat.com,
len.brown@intel.com, linux-kernel@vger.kernel.org,
mgorman@suse.de, naveen.n.rao@linux.vnet.ibm.com,
rafael.j.wysocki@intel.com, ravi.v.shankar@intel.com,
ricardo.neri@intel.com, rostedt@goodmis.org,
srikar@linux.vnet.ibm.com, srinivas.pandruvada@linux.intel.com,
v-songbaohua@oppo.com, vincent.guittot@linaro.org,
vschneid@redhat.com, x86@kernel.org, yangyicong@hisilicon.com,
yu.c.chen@intel.com
Subject: Re: [PATCH] sched/fair: Add SMT4 group_smt_balance handling
Date: Mon, 21 Aug 2023 12:19:40 -0700 [thread overview]
Message-ID: <61cb0511b15612f43f390c750d2e9325bd7af4dd.camel@linux.intel.com> (raw)
In-Reply-To: <4118c2e3-fd34-2ebe-3faa-1c6ac9cbbac2@linux.vnet.ibm.com>
On Mon, 2023-08-07 at 15:06 +0530, Shrikanth Hegde wrote:
> >
> > From: Tim Chen <tim.c.chen@linux.intel.com>
> > Date: Fri, 14 Jul 2023 16:09:30 -0700
> > Subject: [PATCH] sched/fair: Add SMT4 group_smt_balance handling
> >
> > For SMT4, any group with more than 2 tasks will be marked as
> > group_smt_balance. Retain the behaviour of group_has_spare by marking
> > the busiest group as the group which has the least number of idle_cpus.
> >
> > Also, handle rounding effect of adding (ncores_local + ncores_busy)
> > when the local is fully idle and busy group has more than 2 tasks.
> > Local group should try to pull at least 1 task in this case.
> >
> > Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
> > ---
> > kernel/sched/fair.c | 18 ++++++++++++++++--
> > 1 file changed, 16 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index a87988327f88..566686c5f2bd 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -9563,7 +9563,7 @@ static inline long sibling_imbalance(struct lb_env *env,
> > imbalance /= ncores_local + ncores_busiest;
> >
> > /* Take advantage of resource in an empty sched group */
> > - if (imbalance == 0 && local->sum_nr_running == 0 &&
> > + if (imbalance <= 1 && local->sum_nr_running == 0 &&
> > busiest->sum_nr_running > 1)
> > imbalance = 2;
> >
> > @@ -9751,6 +9751,20 @@ static bool update_sd_pick_busiest(struct lb_env *env,
> > break;
> >
> > case group_smt_balance:
> > + /* no idle cpus on both groups handled by group_fully_busy below */
> > + if (sgs->idle_cpus != 0 || busiest->idle_cpus != 0) {
> > + if (sgs->idle_cpus > busiest->idle_cpus)
> > + return false;
> > + if (sgs->idle_cpus < busiest->idle_cpus)
> > + return true;
> > + if (sgs->sum_nr_running <= busiest->sum_nr_running)
> > + return false;
> > + else
> > + return true;
> > + }
> > + goto fully_busy;
> > + break;
> > +
> > case group_fully_busy:
> > /*
> > * Select the fully busy group with highest avg_load. In
> > @@ -9763,7 +9777,7 @@ static bool update_sd_pick_busiest(struct lb_env *env,
> > * select the 1st one, except if @sg is composed of SMT
> > * siblings.
> > */
> > -
> > +fully_busy:
> > if (sgs->avg_load < busiest->avg_load)
> > return false;
> >
>
> Hi Tim, Peter.
>
> group_smt_balance(cluster scheduling), patches are in tip/sched/core. I dont
> see this above patch there yet. Currently as is, this can cause function difference
> in SMT4 systems( such as Power10).
>
> Can we please have the above patch as well in tip/sched/core?
>
> Acked-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Hi Peter,
Just back from my long vacation. Wonder if you have any comments on the above patch
for fixing the SMT4 case?
Tim
next prev parent reply other threads:[~2023-08-21 19:19 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 [this message]
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
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
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