From: Valentin Schneider <vschneid@redhat.com>
To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: "Peter Zijlstra (Intel)" <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>,
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>,
Tim Chen <tim.c.chen@linux.intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
"Tim C . Chen" <tim.c.chen@intel.com>
Subject: Re: [PATCH v2 3/7] sched: Teach arch_asym_cpu_priority() the idle state of SMT siblings
Date: Thu, 22 Dec 2022 16:56:10 +0000 [thread overview]
Message-ID: <xhsmhtu1ne5sl.mognet@vschneid.remote.csb> (raw)
In-Reply-To: <20221222045505.GB407@ranerica-svr.sc.intel.com>
On 21/12/22 20:55, Ricardo Neri wrote:
> On Wed, Dec 21, 2022 at 06:12:52PM +0100, Dietmar Eggemann wrote:
>> Imagine an arch w/ SD_ASYM_PACKING on SMT & MC overwriting
>> arch_asym_cpu_priority(). `bool check_smt` wouldn't be sufficient to
>> know whether a call to something like sched_smt_siblings_idle()
>> (is_core_idle()) which iterates over cpu_smt_mask(cpu) would make sense.
>
> Agreed. I was hoping I could get away with this. x86 would not have the
> the SD_ASYM_PACKING flag at the SMT level and Power7 would ignore
> `check_smt`. :)
>
> Callers of sched_asym_prefer() could use the flags of the sched domain to
> check if we are at the SMT level.
>
> I rescanned the code again and it looks like the needed sched domain flags
> are available in all the places sched_asym_prefer() is called. The only
> exception is asym_smt_can_pull_tasks(), but we already know that we don't
> need such check. (We are looking for the sched group priority, regardless
> of the idle state of the SMT siblings).
>
Given this is fed back to arch code, another option here would be to feed
the topology level this is happening at. You get it via sd->level and it
maps back into the arch's sched_domain_topology_level array.
Though the SD flags are probably the more generic solution.
next prev parent reply other threads:[~2022-12-22 16:57 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-22 20:35 [PATCH v2 0/7] x86/sched: Avoid unnecessary migrations within SMT domains Ricardo Neri
2022-11-22 20:35 ` [PATCH v2 1/7] sched/fair: Generalize asym_packing logic for SMT local sched group Ricardo Neri
2022-12-06 17:22 ` Dietmar Eggemann
2022-12-12 17:53 ` Ricardo Neri
2022-12-21 13:03 ` Dietmar Eggemann
2022-12-22 4:32 ` Ricardo Neri
2022-12-22 11:12 ` Dietmar Eggemann
2022-12-23 13:11 ` Ricardo Neri
2022-12-22 16:55 ` Valentin Schneider
2022-12-29 4:00 ` Ricardo Neri
2023-01-11 16:04 ` Valentin Schneider
2023-01-13 19:02 ` Ricardo Neri
2023-01-16 4:05 ` Ricardo Neri
2023-01-16 19:07 ` Valentin Schneider
2023-01-17 12:49 ` Ricardo Neri
2022-11-22 20:35 ` [PATCH v2 2/7] sched: Prepare sched_asym_prefer() to handle idle state of SMT siblings Ricardo Neri
2022-11-22 20:35 ` [PATCH v2 3/7] sched: Teach arch_asym_cpu_priority() the " Ricardo Neri
2022-12-06 17:54 ` Dietmar Eggemann
2022-12-12 17:54 ` Ricardo Neri
2022-12-21 17:12 ` Dietmar Eggemann
2022-12-22 4:55 ` Ricardo Neri
2022-12-22 16:56 ` Valentin Schneider [this message]
2022-11-22 20:35 ` [PATCH v2 4/7] sched/fair: Introduce sched_smt_siblings_idle() Ricardo Neri
2022-12-06 18:03 ` Dietmar Eggemann
2022-12-12 17:54 ` Ricardo Neri
2022-12-22 11:12 ` Dietmar Eggemann
2022-12-22 16:56 ` Valentin Schneider
2022-12-24 5:28 ` Ricardo Neri
2022-12-28 15:29 ` Chen Yu
2022-12-30 0:17 ` Ricardo Neri
2023-01-10 19:21 ` Valentin Schneider
2022-11-22 20:35 ` [PATCH v2 5/7] x86/sched: Remove SD_ASYM_PACKING from the "SMT" domain Ricardo Neri
2022-12-08 16:03 ` Ionela Voinescu
2022-12-14 16:59 ` Ricardo Neri
2022-12-15 16:48 ` Valentin Schneider
2022-12-20 0:42 ` Ricardo Neri
2022-12-22 16:56 ` Valentin Schneider
2022-12-29 19:02 ` Ricardo Neri
2023-01-10 19:17 ` Valentin Schneider
2023-01-13 1:31 ` Ricardo Neri
2022-11-22 20:35 ` [PATCH v2 6/7] x86/sched/itmt: Give all SMT siblings of a core the same priority Ricardo Neri
2022-11-22 20:35 ` [PATCH v2 7/7] x86/sched/itmt: Consider the idle state of SMT siblings Ricardo Neri
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