From: Tim Chen <tim.c.chen@linux.intel.com>
To: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
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, peterz@infradead.org
Subject: Re: [PATCH] sched/fair: Add SMT4 group_smt_balance handling
Date: Wed, 06 Sep 2023 08:42:44 -0700 [thread overview]
Message-ID: <cce18bb7961861eb16f8f9829660cc59779766c3.camel@linux.intel.com> (raw)
In-Reply-To: <e40f93e5-d4a2-5751-1e2f-dcc987c0eb21@linux.vnet.ibm.com>
On Wed, 2023-09-06 at 14:59 +0530, Shrikanth Hegde wrote:
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 6e7ee2efc1ba..48e9ab7f8a87 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -9764,16 +9764,9 @@ static bool update_sd_pick_busiest(struct lb_env *env,
> >
> > case group_smt_balance:
> > /* no idle cpus on both groups handled by group_fully_busy below */
>
> Please add a comment here explaining the fall-through and spare logic.
>
Sure.
> > - 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;
> > - }
> > + if (sgs->idle_cpus != 0 || busiest->idle_cpus != 0)
> > + goto has_spare;
> > +
> > goto fully_busy;
>
> This can fall through without the additional goto statement no?
>
There is an unconditional goto fully_busy so won't fall through and
compiler won't complain.
> >
> > case group_fully_busy:
> > @@ -9809,6 +9802,7 @@ static bool update_sd_pick_busiest(struct lb_env *env,
> > * as we do not want to pull task off SMT core with one task
> > * and make the core idle.
> > */
> > +has_spare:
> > if (smt_vs_nonsmt_groups(sds->busiest, sg)) {
> > if (sg->flags & SD_SHARE_CPUCAPACITY && sgs->sum_h_nr_running <= 1)
> > return false;
> >
> >
> >
Tim
next prev parent reply other threads:[~2023-09-06 15:42 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 [this message]
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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