From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nathan Lynch <nathanl@linux.ibm.com>,
Gautham R Shenoy <ego@linux.vnet.ibm.com>,
Michael Neuling <mikey@neuling.org>,
Peter Zijlstra <peterz@infradead.org>,
Jordan Niethe <jniethe5@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Nicholas Piggin <npiggin@gmail.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Oliver O'Halloran <oohall@gmail.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH v4 07/10] Powerpc/numa: Detect support for coregroup
Date: Fri, 31 Jul 2020 14:48:59 +0530 [thread overview]
Message-ID: <20200731091859.GG14603@linux.vnet.ibm.com> (raw)
In-Reply-To: <8736585djw.fsf@mpe.ellerman.id.au>
* Michael Ellerman <mpe@ellerman.id.au> [2020-07-31 17:49:55]:
> Srikar Dronamraju <srikar@linux.vnet.ibm.com> writes:
> > Add support for grouping cores based on the device-tree classification.
> > - The last domain in the associativity domains always refers to the
> > core.
> > - If primary reference domain happens to be the penultimate domain in
> > the associativity domains device-tree property, then there are no
> > coregroups. However if its not a penultimate domain, then there are
> > coregroups. There can be more than one coregroup. For now we would be
> > interested in the last or the smallest coregroups.
>
> This still doesn't tell me what a coregroup actually represents.
>
> I get that it's a grouping of cores, and that the device tree specifies
> it for us, but grouping based on what?
>
We have just abstracted the fact that we are creating a sub-group of cores
within a DIE. We are limiting to one sub-group per core. However this would
allow the firmware the flexibility to vary the grouping. Once the firmware
starts using this group, we could add more code to detect the type of
grouping and adjust the sd domain flags accordingly.
> I think the answer is we aren't being told by firmware, it's just a
> grouping based on some opaque performance characteristic and we just
> have to take that as given.
>
This is partially true. At this time, we dont have firmwares that can
exploit this code. Once the firmwares start using this grouping, we could
add more code to align the grouping to the scheduler topology.
> But please explain that clearly in the change log and the code comments.
>
Okay, I will do the needful.
> cheers
>
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2020-07-31 9:21 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 5:32 [PATCH v4 00/10] Coregroup support on Powerpc Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 01/10] powerpc/smp: Fix a warning under !NEED_MULTIPLE_NODES Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 02/10] powerpc/smp: Merge Power9 topology with Power topology Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 03/10] powerpc/smp: Move powerpc_topology above Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 04/10] powerpc/smp: Move topology fixups into a new function Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 05/10] powerpc/smp: Dont assume l2-cache to be superset of sibling Srikar Dronamraju
2020-07-27 5:32 ` [PATCH v4 06/10] powerpc/smp: Generalize 2nd sched domain Srikar Dronamraju
2020-07-30 5:55 ` Gautham R Shenoy
2020-07-31 7:45 ` Michael Ellerman
2020-07-31 9:29 ` Srikar Dronamraju
2020-07-31 12:22 ` Michael Ellerman
2020-07-27 5:32 ` [PATCH v4 07/10] Powerpc/numa: Detect support for coregroup Srikar Dronamraju
2020-07-31 7:49 ` Michael Ellerman
2020-07-31 9:18 ` Srikar Dronamraju [this message]
2020-07-31 11:31 ` Michael Ellerman
2020-07-27 5:32 ` [PATCH v4 08/10] powerpc/smp: Allocate cpumask only after searching thread group Srikar Dronamraju
2020-07-31 7:52 ` Michael Ellerman
2020-07-31 9:49 ` Srikar Dronamraju
2020-07-31 12:14 ` Michael Ellerman
2020-07-27 5:32 ` [PATCH v4 09/10] Powerpc/smp: Create coregroup domain Srikar Dronamraju
2020-07-27 18:52 ` Gautham R Shenoy
2020-07-28 15:03 ` Valentin Schneider
2020-07-29 6:13 ` Srikar Dronamraju
2020-07-31 1:05 ` Valentin Schneider
2020-08-03 6:01 ` Srikar Dronamraju
2020-07-31 7:36 ` Gautham R Shenoy
2020-07-27 5:32 ` [PATCH v4 10/10] powerpc/smp: Implement cpu_to_coregroup_id Srikar Dronamraju
2020-07-31 8:02 ` Michael Ellerman
2020-07-31 9:58 ` Srikar Dronamraju
2020-07-31 11:29 ` Michael Ellerman
2020-07-30 17:22 ` [PATCH v4 00/10] Coregroup support on Powerpc Srikar Dronamraju
-- strict thread matches above, loose matches on Subject: below --
2020-07-27 5:17 Srikar Dronamraju
2020-07-27 5:18 ` [PATCH v4 07/10] Powerpc/numa: Detect support for coregroup Srikar Dronamraju
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