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Mon, 20 Jul 2020 07:20:18 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AE76F4C044; Mon, 20 Jul 2020 07:20:16 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by d06av22.portsmouth.uk.ibm.com (Postfix) with SMTP; Mon, 20 Jul 2020 07:20:16 +0000 (GMT) Date: Mon, 20 Jul 2020 12:50:16 +0530 From: Srikar Dronamraju To: Gautham R Shenoy Subject: Re: [PATCH 04/11] powerpc/smp: Enable small core scheduling sooner Message-ID: <20200720072016.GE21103@linux.vnet.ibm.com> References: <20200714043624.5648-1-srikar@linux.vnet.ibm.com> <20200714043624.5648-5-srikar@linux.vnet.ibm.com> <20200717054821.GD25851@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20200717054821.GD25851@in.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-20_04:2020-07-17, 2020-07-20 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 spamscore=0 impostorscore=0 malwarescore=0 adultscore=0 phishscore=0 mlxscore=0 suspectscore=0 bulkscore=0 lowpriorityscore=0 clxscore=1015 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007200052 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: Srikar Dronamraju Cc: Nathan Lynch , Oliver OHalloran , Michael Neuling , Michael Ellerman , Anton Blanchard , linuxppc-dev , Nick Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" * Gautham R Shenoy [2020-07-17 11:18:21]: > On Tue, Jul 14, 2020 at 10:06:17AM +0530, Srikar Dronamraju wrote: > > Enable small core scheduling as soon as we detect that we are in a > > system that supports thread group. Doing so would avoid a redundant > > check. > > > > Cc: linuxppc-dev > > Cc: Michael Ellerman > > Cc: Nick Piggin > > Cc: Oliver OHalloran > > Cc: Nathan Lynch > > Cc: Michael Neuling > > Cc: Anton Blanchard > > Cc: Gautham R Shenoy > > Cc: Vaidyanathan Srinivasan > > Signed-off-by: Srikar Dronamraju > > I don't see a problem with this. > > However, since we are now going to be maintaining a single topology > structure, wouldn't it be better to collate all the changes being made > to the mask_functions/flags/names of this structure within a single > function so that it becomes easier to keep track of what all changes > are going into the topology and why are we doing it? > My intent was to move the topology updates early as soon as they are detected. Currently the shared_cache want cannot be detected early. But I think its possible to detect shared_cache early with some cleanups. And if we do, then we should be able to call this up pretty early. > > > --- > > arch/powerpc/kernel/smp.c | 12 ++++++------ > > 1 file changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c > > index 24529f6134aa..7d430fc536cc 100644 > > --- a/arch/powerpc/kernel/smp.c > > +++ b/arch/powerpc/kernel/smp.c > > @@ -892,6 +892,12 @@ static int init_big_cores(void) > > } > > > > has_big_cores = true; > > + > > +#ifdef CONFIG_SCHED_SMT > > + pr_info("Big cores detected. Using small core scheduling\n"); > > + powerpc_topology[0].mask = smallcore_smt_mask; > > +#endif > > + > > return 0; > > } > > > > @@ -1383,12 +1389,6 @@ void __init smp_cpus_done(unsigned int max_cpus) > > > > dump_numa_cpu_topology(); > > > > -#ifdef CONFIG_SCHED_SMT > > - if (has_big_cores) { > > - pr_info("Big cores detected but using small core scheduling\n"); > > - powerpc_topology[0].mask = smallcore_smt_mask; > > - } > > -#endif > > set_sched_topology(powerpc_topology); > > } > > > > -- > > 2.17.1 > > -- Thanks and Regards Srikar Dronamraju