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 for <linuxppc-dev@lists.ozlabs.org> from <srikar@linux.vnet.ibm.com>;
 Mon, 20 Aug 2018 19:05:11 +0100
Date: Mon, 20 Aug 2018 11:05:03 -0700
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
 Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 Michael Neuling <mikey@neuling.org>,
 Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
 Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>,
 Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>,
 "Oliver O'Halloran" <oohall@gmail.com>,
 Nicholas Piggin <npiggin@gmail.com>,
 Murilo Opsfelder Araujo <muriloo@linux.ibm.com>,
 Anton Blanchard <anton@samba.org>, linuxppc-dev@lists.ozlabs.org,
 linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 2/2] powerpc: Use cpu_smallcore_sibling_mask at SMT
 level on bigcores
Reply-To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
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* Gautham R. Shenoy <ego@linux.vnet.ibm.com> [2018-08-20 11:11:44]:

> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
> 
> Each of the SMT4 cores forming a big-core are more or less independent
> units. Thus when multiple tasks are scheduled to run on the fused
> core, we get the best performance when the tasks are spread across the
> pair of SMT4 cores.
> 
> This patch achieves this by setting the SMT level mask to correspond
> to the smallcore sibling mask on big-core systems. This patch also
> ensures that while checked for shared-caches on big-core system, we
> use the smallcore_sibling_mask to compare with the l2_cache_mask.
> This ensure that the CACHE level sched-domain is created, whose groups
> correspond to the threads of the big-core.
> 
> With this patch, the SMT sched-domain with SMT=8,4,2 on big-core
> systems are as follows:


Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>