> On Mon, 17 Apr 2023 23:31:01 +0200 Lorenzo Bianconi wrote: > > > If it's that then I'm with Eric. There are many ways to keep the pages > > > in use, no point working around one of them and not the rest :( > > > > I was not clear here, my fault. What I mean is I can see the returned > > pages counter increasing from time to time, but during most of tests, > > even after 2h the tcp traffic has stopped, page_pool_release_retry() > > still complains not all the pages are returned to the pool and so the > > pool has not been deallocated yet. > > The chunk of code in my first email is just to demonstrate the issue > > and I am completely fine to get a better solution :) > > Your problem is perhaps made worse by threaded NAPI, you have > defer-free skbs sprayed across all cores and no NAPI there to > flush them :( yes, exactly :) > > > I guess we just need a way to free the pool in a reasonable amount > > of time. Agree? > > Whether we need to guarantee the release is the real question. yes, this is the main goal of my email. The defer-free skbs behaviour seems in contrast with the page_pool pending pages monitor mechanism or at least they do not work well together. @Jesper, Ilias: any input on it? > Maybe it's more of a false-positive warning. > > Flushing the defer list is probably fine as a hack, but it's not > a full fix as Eric explained. False positive can still happen. agree, it was just a way to give an idea of the issue, not a proper solution. Regards, Lorenzo > > I'm ambivalent. My only real request wold be to make the flushing > a helper in net/core/dev.c rather than open coded in page_pool.c. > > Somewhat related - Eric, do we need to handle defer_list in dev_cpu_dead()?
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