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To: Michal Hocko Cc: hannes@cmpxchg.org, roman.gushchin@linux.dev, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, lizefan.x@bytedance.com, wuyun.abel@bytedance.com References: <20220904040241.1708-1-hezhongkun.hzk@bytedance.com> <0e5f380b-9201-0f56-9144-ce8449491fc8@bytedance.com> <93d76370-6c43-5560-9a5f-f76a8cc979e0@bytedance.com> From: Zhongkun He In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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. > Hi Michal, thanks for your suggestion and reply. > Are you going to pursue that path? Yes，I'll give it a try as it makes sense to modify the policy dynamically. Thanks.