On 4/1/22 10:02 AM, Miklos Szeredi wrote: > On Fri, 1 Apr 2022 at 17:36, Jens Axboe <axboe@xxxxxxxxx> wrote: > >> I take it you're continually reusing those slots? > > Yes. > >> If you have a test >> case that'd be ideal. Agree that it sounds like we just need an >> appropriate breather to allow fput/task_work to run. Or it could be the >> deferral free of the fixed slot. > > Adding a breather could make the worst case latency be large. I think > doing the fput synchronously would be better in general. fput() isn't sync, it'll just offload to task_work. There are some dependencies there that would need to be checked. But we'll find a way to deal with it. > I test this on an VM with 8G of memory and run the following: > > ./forkbomb 14 & > # wait till 16k processes are forked > for i in `seq 1 100`; do ./procreads u; done > > You can compare performance with plain reads (./procreads p), the > other tests don't work on public kernels. OK, I'll check up on this, but probably won't have time to do so before early next week. -- Jens Axboe
