From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>,
Gautham R Shenoy <ego@linux.vnet.ibm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Geetika Moolchandani <Geetika.Moolchandani1@ibm.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Laurent Dufour <ldufour@linux.ibm.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH v2 0/3] Updates to powerpc for robust CPU online/offline
Date: Mon, 23 Aug 2021 11:37:19 +0200 [thread overview]
Message-ID: <YSNsT1Mr1hcNr6iz@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210823093437.GJ21942@linux.vnet.ibm.com>
On Mon, Aug 23, 2021 at 03:04:37PM +0530, Srikar Dronamraju wrote:
> * Peter Zijlstra <peterz@infradead.org> [2021-08-23 10:33:30]:
>
> > On Sat, Aug 21, 2021 at 03:55:32PM +0530, Srikar Dronamraju wrote:
> > > Scheduler expects unique number of node distances to be available
> > > at boot. It uses node distance to calculate this unique node
> > > distances. On Power Servers, node distances for offline nodes is not
> > > available. However, Power Servers already knows unique possible node
> > > distances. Fake the offline node's distance_lookup_table entries so
> > > that all possible node distances are updated.
> > >
> > > For example distance info from numactl from a fully populated 8 node
> > > system at boot may look like this.
> > >
> > > node distances:
> > > node 0 1 2 3 4 5 6 7
> > > 0: 10 20 40 40 40 40 40 40
> > > 1: 20 10 40 40 40 40 40 40
> > > 2: 40 40 10 20 40 40 40 40
> > > 3: 40 40 20 10 40 40 40 40
> > > 4: 40 40 40 40 10 20 40 40
> > > 5: 40 40 40 40 20 10 40 40
> > > 6: 40 40 40 40 40 40 10 20
> > > 7: 40 40 40 40 40 40 20 10
> > >
> > > However the same system when only two nodes are online at boot, then
> > > distance info from numactl will look like
> > > node distances:
> > > node 0 1
> > > 0: 10 20
> > > 1: 20 10
> > >
> > > With the faked numa distance at boot, the node distance table will look
> > > like
> > > node 0 1 2
> > > 0: 10 20 40
> > > 1: 20 10 40
> > > 2: 40 40 10
> > >
> > > The actual distance will be populated once the nodes are onlined.
> >
> > How did you want all this merged? I picked up Valentin's patch, do you
> > want me to pick up these PowerPC patches in the same tree, or do you
> > want to route them seperately?
>
> While both (the patch you accepted and this series) together help solve the
> problem, I think there is no hard dependency between the two. Hence I would
> think it should be okay to go through the powerpc tree.
>
OK, works for me, thanks!
prev parent reply other threads:[~2021-08-23 9:39 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-21 10:25 [PATCH v2 0/3] Updates to powerpc for robust CPU online/offline Srikar Dronamraju
2021-08-21 10:25 ` [PATCH v2 1/3] powerpc/numa: Print debug statements only when required Srikar Dronamraju
2021-08-23 9:21 ` Laurent Dufour
2021-08-23 9:38 ` Srikar Dronamraju
2021-08-25 13:01 ` Michael Ellerman
2021-08-26 4:47 ` Srikar Dronamraju
2021-08-21 10:25 ` [PATCH v2 2/3] powerpc/numa: Update cpu_cpu_map on CPU online/offline Srikar Dronamraju
2021-08-21 10:25 ` [PATCH v2 3/3] powerpc/numa: Fill distance_lookup_table for offline nodes Srikar Dronamraju
2021-08-26 13:36 ` Michael Ellerman
2021-09-01 10:22 ` Srikar Dronamraju
2021-09-23 11:17 ` Michael Ellerman
2021-09-23 17:57 ` Srikar Dronamraju
2021-10-11 11:45 ` Michael Ellerman
2021-08-23 8:33 ` [PATCH v2 0/3] Updates to powerpc for robust CPU online/offline Peter Zijlstra
2021-08-23 9:34 ` Srikar Dronamraju
2021-08-23 9:37 ` Peter Zijlstra [this message]
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