From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 3/4] sched/topology: remove smt_gain
Date: Wed, 5 Sep 2018 01:50:29 -0700 [thread overview]
Message-ID: <20180905085029.GA57420@linux.vnet.ibm.com> (raw)
In-Reply-To: <CAKfTPtBVLWgtRJpP0nTOVpkwJse6BwrGa28o4qat0T3kOvEAfw@mail.gmail.com>
* Vincent Guittot <vincent.guittot@linaro.org> [2018-09-05 09:36:42]:
> >
> > I dont know of any systems that have come with single threaded and
> > multithreaded. However some user can still offline few threads in a core
> > while leaving other cores untouched. I dont really know why somebody
> > would want to do it. For example, some customer was toying with SMT 3
> > mode in a SMT 8 power8 box.
>
> In this case, it means that we have the same core capacity whatever
> the number of CPUs
> and a core with SMT 3 will be set with the same compute capacity as
> the core with SMT 8.
> Does it still make sense ?
>
To me it make sense atleast from a power 8 perspective, because SMT 1 >
SMT 2 > SMT 4 > SMT8. So if one core is configured for SMT 2 and other
core is configured for SMT4; all threads being busy, the individual
threads running on SMT2 core will complete more work than SMT 4 core
threads.
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2018-09-05 8:50 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-29 13:19 [PATCH 0/4] sched/numa: remove unused code Vincent Guittot
2018-08-29 13:19 ` [PATCH 1/4] sched/numa: remove unused code from update_numa_stats() Vincent Guittot
2018-09-04 6:39 ` Srikar Dronamraju
2018-09-10 10:19 ` [tip:sched/core] sched/numa: Remove " tip-bot for Vincent Guittot
2018-08-29 13:19 ` [PATCH 2/4] sched/numa: remove unused nr_running field Vincent Guittot
2018-09-04 6:40 ` Srikar Dronamraju
2018-09-10 10:20 ` [tip:sched/core] sched/numa: Remove unused numa_stats::nr_running field tip-bot for Vincent Guittot
2018-08-29 13:19 ` [RFC PATCH 3/4] sched/topology: remove smt_gain Vincent Guittot
2018-08-29 14:08 ` Qais Yousef
2018-08-29 14:42 ` Vincent Guittot
2018-09-07 12:42 ` Peter Zijlstra
2018-09-10 11:23 ` Qais Yousef
2018-09-04 8:24 ` Srikar Dronamraju
2018-09-04 9:36 ` Vincent Guittot
2018-09-04 10:37 ` Srikar Dronamraju
2018-09-05 7:36 ` Vincent Guittot
2018-09-05 8:50 ` Srikar Dronamraju [this message]
2018-09-05 9:11 ` Vincent Guittot
2018-09-05 11:14 ` Srikar Dronamraju
2018-09-06 9:21 ` Vincent Guittot
2018-09-10 11:05 ` Qais Yousef
2018-09-10 10:07 ` [tip:sched/core] sched/fair: Fix scale_rt_capacity() for SMT tip-bot for Vincent Guittot
2018-12-11 15:31 ` [tip:sched/core] sched/topology: Remove the ::smt_gain field from 'struct sched_domain' tip-bot for Vincent Guittot
2018-08-29 13:19 ` [RFC PATCH 4/4] sched/topology: remove unused sd param from arch_scale_cpu_capacity() Vincent Guittot
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