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t=1675770584; bh=RgVgJCrLkTAvmwUYHcxZco9kHb4tcMhvYtkGp0jn4Uw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tLvug3F3Minye5YXeEpg6rj46hLxC8/p8PnepfTsimLxWG/Th4ZPg+Gppcs2IcXjj YO/kg3jMl1KIODxpVAbL/icPosTwmqgKrebGucclQCTk0BUKZb+qDeIWX9uX0G6kiE vFO/v77bmwVwwMnmFrf7guquDrQDLKHmI6fbPJ17akGjL82op+LxtSRmVVl/h54+8Y Olta0cI33IiMJCCYZrEPuR/VE5rXtKwbD+zVYYSY0iioEp8sjr6VZbyBI7TrVoYUQi 4TnJseDLpVDQuCvoCoUTCJyvrgYtEDJUd3jEQorADL8yVmZ4eVu2JtzvcTCvgImn24 XbTwOQWCQqhTA== Date: Tue, 7 Feb 2023 12:49:41 +0100 From: Frederic Weisbecker To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: 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 Subject: Re: [PATCH 1/2] sched/isolation: Merge individual nohz_full features into a common housekeeping flag Message-ID: References: <20230203232409.163847-1-frederic@kernel.org> <20230203232409.163847-2-frederic@kernel.org> <20230206155107.GA31453@blackbody.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230206155107.GA31453@blackbody.suse.cz> X-Rspamd-Queue-Id: 24EDD140008 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 7dpsw5cg7kj5idggryhpy8ed7fgh9bf7 X-HE-Tag: 1675770585-106449 X-HE-Meta: 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 zfBabEIj 05ugOyjd1y1928cbqIflhloVgO5JM/wUl2wD2MyDK/HjKO8WjyyubbOjRz772psG/a9Bsl1oHL/QO4o0R3plP+6yJemjRIZeOjT/1eVJoMraMtfOofMZgrBIAJVq8Y/WjQO3QUIoe61lCt0p9/Iy6dUU3GM1RJaJNABQaDZHWLnuxciSnX+OiooqeF1y2wMJO0wez4CJ+p4fTRUJJ3+XgjShQMBmGwE43QvbnlJv8BRyGfwXRDVw7BsM+EnuZqfhppy4WpyCKuXkGzI7S+1KMHSANjaSpUKQEFwMRPtVKZ+LN0i8qCDB9Suv7B4e8i3prj5SDQuYJ7ml2NBdBu4x4wkpHg/ILSj81MAXeLRpF6aqOti3z1A5v9s5WoZ9VvjOTLfWTAc28Nqfjk1eDHD+uSYRu00K5AuaYhCEI 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 Mon, Feb 06, 2023 at 04:51:09PM +0100, Michal Koutný wrote: > Hello Frederic. > > On Sat, Feb 04, 2023 at 12:24:08AM +0100, Frederic Weisbecker wrote: > > The individual isolation features turned on by nohz_full were initially > > split in order for each of them to be tunable through cpusets. However > > plans have changed in favour of an interface (be it cpusets or sysctl) > > grouping all these features to be turned on/off altogether. > > Then should the need ever arise, the interface can still be expanded > > to handle the individual isolation features. > > > > Therefore the current isolation split between tick/timer/workqueue/rcu/ > > kthreads/misc doesn't make sense anymore. > > Why it doesn't make sense? I think it's a useful annotation of > respective operations wrt CPU isolation. But what do we need these annotations for? The only outcome I've ever seen with these is that it confuses everyone. > > The grouping you did into HK_TYPE_KERNEL_NOISE (or even coarser) should > IMO be done at the place where it'll be exposed into the favored > interface (like it's with nohz_full=). That being said I should reserve the grouping to HK_TYPE_KERNEL_NOISE when I'll introduce the cpuset interface. This way I can add the support for each part smoothly. For example first patch moves HK_TYPE_TIMER to HK_TYPE_KERNEL_NOISE and unbound timers are supported by cpuset.kernel_noise, second patch moves HK_TYPE_WQ to HK_TYPE_KERNEL_NOISE and unbound workqueues are supported by cpuset.kernel_noise, etc until all of them turned by nohz_full= are supported... This is what I'm doing in fact but I'm so slow to write this patchset... Thanks.