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Fri, 24 Jul 2020 07:11:13 +0000 Received: from b01ledav005.gho.pok.ibm.com (b01ledav005.gho.pok.ibm.com [9.57.199.110]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 06O7BCdF19661128 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 24 Jul 2020 07:11:12 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 46120AE062; Fri, 24 Jul 2020 07:11:12 +0000 (GMT) Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 91C6FAE05C; Fri, 24 Jul 2020 07:11:11 +0000 (GMT) Received: from sofia.ibm.com (unknown [9.85.93.226]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 24 Jul 2020 07:11:11 +0000 (GMT) Received: by sofia.ibm.com (Postfix, from userid 1000) id 1815A2E340E; Fri, 24 Jul 2020 12:41:08 +0530 (IST) Date: Fri, 24 Jul 2020 12:41:08 +0530 From: Gautham R Shenoy To: Srikar Dronamraju Subject: Re: [PATCH v3 05/10] powerpc/smp: Dont assume l2-cache to be superset of sibling Message-ID: <20200724071108.GD21415@in.ibm.com> References: <20200723085116.4731-1-srikar@linux.vnet.ibm.com> <20200723085116.4731-6-srikar@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200723085116.4731-6-srikar@linux.vnet.ibm.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-24_01:2020-07-24, 2020-07-23 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 bulkscore=0 adultscore=0 suspectscore=0 phishscore=0 impostorscore=0 spamscore=0 clxscore=1015 mlxscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007240052 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: ego@linux.vnet.ibm.com Cc: Nathan Lynch , Gautham R Shenoy , Michael Neuling , Peter Zijlstra , LKML , Nicholas Piggin , Valentin Schneider , Oliver O'Halloran , Jordan Niethe , linuxppc-dev , Ingo Molnar Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Jul 23, 2020 at 02:21:11PM +0530, Srikar Dronamraju wrote: > Current code assumes that cpumask of cpus sharing a l2-cache mask will > always be a superset of cpu_sibling_mask. > > Lets stop that assumption. cpu_l2_cache_mask is a superset of > cpu_sibling_mask if and only if shared_caches is set. > > Cc: linuxppc-dev > Cc: LKML > Cc: Michael Ellerman > Cc: Nicholas Piggin > Cc: Anton Blanchard > Cc: Oliver O'Halloran > Cc: Nathan Lynch > Cc: Michael Neuling > Cc: Gautham R Shenoy > Cc: Ingo Molnar > Cc: Peter Zijlstra > Cc: Valentin Schneider > Cc: Jordan Niethe > Signed-off-by: Srikar Dronamraju Reviewed-by: Gautham R. Shenoy > --- > Changelog v1 -> v2: > Set cpumask after verifying l2-cache. (Gautham) > > arch/powerpc/kernel/smp.c | 28 +++++++++++++++------------- > 1 file changed, 15 insertions(+), 13 deletions(-) > > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c > index da27f6909be1..d997c7411664 100644 > --- a/arch/powerpc/kernel/smp.c > +++ b/arch/powerpc/kernel/smp.c > @@ -1194,6 +1194,7 @@ static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int)) > if (!l2_cache) > return false; > > + cpumask_set_cpu(cpu, mask_fn(cpu)); > for_each_cpu(i, cpu_online_mask) { > /* > * when updating the marks the current CPU has not been marked > @@ -1276,29 +1277,30 @@ static void add_cpu_to_masks(int cpu) > * add it to it's own thread sibling mask. > */ > cpumask_set_cpu(cpu, cpu_sibling_mask(cpu)); > + cpumask_set_cpu(cpu, cpu_core_mask(cpu)); > > for (i = first_thread; i < first_thread + threads_per_core; i++) > if (cpu_online(i)) > set_cpus_related(i, cpu, cpu_sibling_mask); > > add_cpu_to_smallcore_masks(cpu); > - /* > - * Copy the thread sibling mask into the cache sibling mask > - * and mark any CPUs that share an L2 with this CPU. > - */ > - for_each_cpu(i, cpu_sibling_mask(cpu)) > - set_cpus_related(cpu, i, cpu_l2_cache_mask); > update_mask_by_l2(cpu, cpu_l2_cache_mask); > > - /* > - * Copy the cache sibling mask into core sibling mask and mark > - * any CPUs on the same chip as this CPU. > - */ > - for_each_cpu(i, cpu_l2_cache_mask(cpu)) > - set_cpus_related(cpu, i, cpu_core_mask); > + if (pkg_id == -1) { > + struct cpumask *(*mask)(int) = cpu_sibling_mask; > + > + /* > + * Copy the sibling mask into core sibling mask and > + * mark any CPUs on the same chip as this CPU. > + */ > + if (shared_caches) > + mask = cpu_l2_cache_mask; > + > + for_each_cpu(i, mask(cpu)) > + set_cpus_related(cpu, i, cpu_core_mask); > > - if (pkg_id == -1) > return; > + } > > for_each_cpu(i, cpu_online_mask) > if (get_physical_package_id(i) == pkg_id) > -- > 2.18.2 >