From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [External] Re: [PATCH] cgroup/cpuset: Add a new isolated mems.policy type. Date: Thu, 8 Sep 2022 09:19:20 +0200 Message-ID: References: <20220904040241.1708-1-hezhongkun.hzk@bytedance.com> <0e5f380b-9201-0f56-9144-ce8449491fc8@bytedance.com> <93d76370-6c43-5560-9a5f-f76a8cc979e0@bytedance.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1662621560; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yklmv2ux9aHaYIhutjyFigStqNyf61xsI5qM8T+Pp2M=; b=XsPHwzskZaYb147v91HjRFvXSb84ItKrVKY4TdypktvPUCZ2ermxWVd6wuWWBL62hWeknq 6NcmpS4lfkIA6SlBKqpvEw22impF8ik4Ke/ZnscUqU7zWcM3fgHpS+TuB6ok1QrNv/Ppp5 kt5N85b5OZvoxs/3u369Z0s2CX7Fv+g= Content-Disposition: inline In-Reply-To: <93d76370-6c43-5560-9a5f-f76a8cc979e0-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> List-ID: Content-Type: text/plain; charset="utf-8" To: Zhongkun He Cc: hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org, wuyun.abel-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org On Wed 07-09-22 21:50:24, Zhongkun He wrote: [...] > > Do you really need to change the policy itself or only the effective > > nodemask? Do you need any other policy than bind and preferred? > > Yes, we need to change the policy, not only his nodemask. we really want > policy is interleave, and extend it to weight-interleave. > Say something like the following > node weight > interleave: 0-3 1:1:1:1 default one by one > weight-interleave: 0-3 1:2:4:6 alloc pages by weight > (User set weight.) > In the actual usecase, the remaining resources of each node are different, > and the use of interleave cannot maximize the use of resources. OK, this seems a separate topic. It would be good to start by proposing that new policy in isolation with the semantic description. > Back to the previous question. > >The question is how to implement that with a sensible semantic. > > Thanks for your analysis and suggestions.It is really difficult to add > policy directly to cgroup for the hierarchical enforcement. It would be a > good idea to add pidfd_set_mempolicy. Are you going to pursue that path? > Also, there is a new idea. > We can try to separate the elements of mempolicy and use them independently. > Mempolicy has two meanings: > nodes:which nodes to use(nodes,0-3), we can use cpuset's effective_mems > directly. > mode:how to use them(bind,prefer,etc). change the mode to a > cpuset->flags,such as CS_INTERLEAVE。 > task_struct->mems_allowed is equal to cpuset->effective_mems,which is > hierarchical enforcement。CS_INTERLEAVE can also be updated into tasks， > just like other flags(CS_SPREAD_PAGE). > When a process needs to allocate memory, it can find the appropriate node to > allocate pages according to the flag and mems_allowed. I am not sure I see the advantage as the mode and nodes are always closely coupled. You cannot really have one wihtout the other. -- Michal Hocko SUSE Labs