On Thu, Dec 07, 2023 at 07:22:12AM +0100, Tobias Huschle wrote: > 3. vhost looping endlessly, waiting for kworker to be scheduled > > I dug a little deeper on what the vhost is doing. I'm not an expert on > virtio whatsoever, so these are just educated guesses that maybe > someone can verify/correct. Please bear with me probably messing up > the terminology. > > - vhost is looping through available queues. > - vhost wants to wake up a kworker to process a found queue. > - kworker does something with that queue and terminates quickly. > > What I found by throwing in some very noisy trace statements was that, > if the kworker is not woken up, the vhost just keeps looping accross > all available queues (and seems to repeat itself). So it essentially > relies on the scheduler to schedule the kworker fast enough. Otherwise > it will just keep on looping until it is migrated off the CPU. Normally it takes the buffers off the queue and is done with it. I am guessing that at the same time guest is running on some other CPU and keeps adding available buffers? -- MST
