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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH 2/2] sched/isolation: Add cpu_is_isolated() API Content-Language: en-US To: =?UTF-8?Q?Michal_Koutn=c3=bd?= Cc: Frederic Weisbecker , LKML , Roman Gushchin , Michal Hocko , Marcelo Tosatti , Leonardo , Johannes Weiner , Shakeel Butt , Muchun Song , Andrew Morton , Peter Zijlstra , Thomas Gleixner , cgroups@vger.kernel.org, linux-mm@kvack.org References: <20230203232409.163847-1-frederic@kernel.org> <20230203232409.163847-3-frederic@kernel.org> <0f388863-9498-e61e-e2dc-965654544489@redhat.com> <20230206154710.GC21332@blackbody.suse.cz> From: Waiman Long In-Reply-To: <20230206154710.GC21332@blackbody.suse.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 X-Rspam-User: X-Rspamd-Queue-Id: 66FCA180021 X-Rspamd-Server: rspam01 X-Stat-Signature: ydyij19m539zhfyefggs4epzdxq1in6h X-HE-Tag: 1675702218-258658 X-HE-Meta: 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 y1JhtJow UCfYFFwTVZAAATcIsIaXzH9CXQa0OCHsQq9cCNXIOY0ExwPUccROaEcDr+WXEPf5D/C1RS1+RCJL+EpoEoo5K48Md3F13zt411+jJwCrbRP8PPfTjkX7HwlS4l6ypLDdMD/iocDChmBQVlbkS10b/I91bd5A3qtKzsxL1np2BNa6fzXEyG/PzkpUI2okEbILAQr9iHFZt9d0eTRVNdA3n/XxGoqMTiIYATvZ9/YHa6Qdl7hOAj6/w0xdtlg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2/6/23 10:47, Michal Koutný wrote: > Hello. > > On Fri, Feb 03, 2023 at 10:53:46PM -0500, Waiman Long wrote: >> CPUs in an isolated cpuset partition is similar to HK_TYPE_DOMAIN CPUs as >> load balancing is disabled. I can add an API to access the cpumask and add >> to this API. However, that list is dynamic as it can be changed at run time. >> Will that be a problem? > I can see a problem already -- as a CPU can be dynamically switched to > "isolated" mode so should all dependent operations support that (switch) > too, i.e. the CPUs local PCP caches would have to be drained when the > CPU enters isolation. I see the long term goal is to have more isolation capability to be done dynamically. However, we are not there yet. There is still a lot of work to do to achieve that. > >> Or should that be used separately? > It'd be nice to have both (cpuset and cmdline flags) eventually unified. > > Alas, it only leads me conservatively to: > > #ifndef CONFIG_CPUSETS > // the proposed implementaion > else > static inline bool cpu_is_isolated(int cpu) { > return true; > } > #endif That is too conservative from my point of view. We can have further discussion when a patch is ready. Cheers, Longman