On Tue 20-04-21 10:20:43, Mike Rapoport wrote: > On Tue, Apr 20, 2021 at 09:04:51AM +0200, Michal Hocko wrote: > > On Mon 19-04-21 18:37:13, Christian König wrote: > > > Am 19.04.21 um 18:11 schrieb Michal Hocko: > > [...] > > > > The question is not whether it is NUMA aware but whether it is useful to > > > > know per-numa data for the purpose the counter is supposed to serve. > > > > > > No, not at all. The pages of a single DMA-buf could even be from different > > > NUMA nodes if the exporting driver decides that this is somehow useful. > > > > As the use of the counter hasn't been explained yet I can only > > speculate. One thing that I can imagine to be useful is to fill gaps in > > our accounting. It is quite often that the memroy accounted in > > /proc/meminfo (or oom report) doesn't add up to the overall memory > > usage. In some workloads the workload can be huge! In many cases there > > are other means to find out additional memory by a subsystem specific > > interfaces (e.g. networking buffers). I do assume that dma-buf is just > > one of those and the counter can fill the said gap at least partially > > for some workloads. That is definitely useful. > > A bit off-topic. > > Michal, I think it would have been nice to have an explanation like above > in Documentation/proc/meminfo, what do you say? Not sure which specific parts (likely the unaccounted memory?) but sure why not. Our /proc/meminfo is rather underdocumented. More information cannot hurt. -- Michal Hocko SUSE Labs
