On Thu, May 19, 2022 at 04:08:15AM +0530, Vaibhav Jain wrote: > [1] Provides a way for user-space to trigger proactive reclaim by introducing > a write-only memcg file 'memory.reclaim'. However reclaim stats like number > of pages scanned and reclaimed is still not directly available to the > user-space. > > This patch proposes to extend [1] to make the memcg file 'memory.reclaim' > readable which returns the number of pages scanned / reclaimed during the > reclaim process from 'struct vmpressure' associated with each memcg. This should > let user-space asses how successful proactive reclaim triggered from memcg > 'memory.reclaim' was ? > > With the patch following command flow is expected: > > # echo "1M" > memory.reclaim > > # cat memory.reclaim > scanned 76 > reclaimed 32 > Yosry already mentioned the race issue with the implementation and I would prefer we don't create any new dependency on vmpressure which I think we should deprecate. Anyways my question is how are you planning to use these metrics i.e. scanned & reclaimed? I wonder if the data you are interested in can be extracted without a stable interface. Have you tried BPF way to get these metrics? We already have a tracepoint in vmscan tracing the scanned and reclaimed.
