From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@techsingularity.net>,
Rik van Riel <riel@surriel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
linuxppc-dev@lists.ozlabs.org,
Nathan Lynch <nathanl@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Scott Cheloha <cheloha@linux.ibm.com>,
Gautham R Shenoy <ego@linux.vnet.ibm.com>,
Geetika Moolchandani <Geetika.Moolchandani1@ibm.com>
Subject: Re: [PATCH 1/3] sched/topology: Allow archs to populate distance map
Date: Tue, 25 May 2021 17:02:35 +0530 [thread overview]
Message-ID: <20210525113235.GM2633526@linux.vnet.ibm.com> (raw)
In-Reply-To: <87h7irglm9.mognet@arm.com>
* Valentin Schneider <valentin.schneider@arm.com> [2021-05-25 11:21:02]:
> On 24/05/21 21:48, Srikar Dronamraju wrote:
> > * Valentin Schneider <valentin.schneider@arm.com> [2021-05-24 15:16:09]:
> >> Ok so from your arch you can figure out the *size* of the set of unique
> >> distances, but not the individual node_distance(a, b)... That's quite
> >> unfortunate.
> >
> > Yes, thats true.
> >
> >>
> >> I suppose one way to avoid the hook would be to write some "fake" distance
> >> values into your distance_lookup_table[] for offline nodes using your
> >> distance_ref_point_depth thing, i.e. ensure an iteration of
> >> node_distance(a, b) covers all distance values [1]. You can then keep patch
> >> 3 around, and that should roughly be it.
> >>
> >
> > Yes, this would suffice but to me its not very clean.
> > static int found[distance_ref_point_depth];
> >
> > for_each_node(node){
> > int i, nd, distance = LOCAL_DISTANCE;
> > goto out;
> >
> > nd = node_distance(node, first_online_node)
> > for (i=0; i < distance_ref_point_depth; i++, distance *= 2) {
> > if (node_online) {
> > if (distance != nd)
> > continue;
> > found[i] ++;
> > break;
> > }
> > if (found[i])
> > continue;
> > distance_lookup_table[node][i] = distance_lookup_table[first_online_node][i];
> > found[i] ++;
> > break;
> > }
> > }
> >
> > But do note: We are setting a precedent for node distance between two nodes
> > to change.
> >
>
> Indeed. AFAICT it's that or the unique-distance-values hook :/
Peter,
Please let me know which approach would you prefer.
I am open to try any other approach too.
In my humble opinion, unique-distance-values hook is more cleaner.
Do you still have any concerns with the unique-distance-values hook?
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2021-05-25 11:33 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 15:44 [PATCH 0/3] Skip numa distance for offline nodes Srikar Dronamraju
2021-05-20 15:44 ` [PATCH 1/3] sched/topology: Allow archs to populate distance map Srikar Dronamraju
2021-05-20 18:56 ` Peter Zijlstra
2021-05-21 2:38 ` Srikar Dronamraju
2021-05-21 8:14 ` Peter Zijlstra
2021-05-21 9:28 ` Srikar Dronamraju
2021-05-24 14:16 ` Valentin Schneider
2021-05-24 16:18 ` Srikar Dronamraju
2021-05-25 10:21 ` Valentin Schneider
2021-05-25 11:32 ` Srikar Dronamraju [this message]
2021-05-28 5:21 ` Srikar Dronamraju
2021-05-28 8:43 ` Peter Zijlstra
2021-05-28 10:24 ` Srikar Dronamraju
2021-05-20 15:44 ` [PATCH 2/3] powerpc/numa: Populate distance map correctly Srikar Dronamraju
2021-05-24 14:16 ` Valentin Schneider
2021-05-24 14:50 ` Srikar Dronamraju
2021-05-20 15:44 ` [PATCH 3/3] sched/topology: Skip updating masks for non-online nodes Srikar Dronamraju
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