> From: Kevin Wolf [mailto:kw...@redhat.com] > > > > > > First of all, I'm not sure if running replay events from > > > qemu_clock_get_ns() is such a great idea. This is not a function that > > > callers expect to change any state. If you absolutely have to do it > > > there instead of in the clock device emulations, maybe restricting it to > > > replaying clock events could make it a bit more harmless. > > > > Only virtual clock is emulated, and host clock is read from the host > > real time sources and therefore has to be saved into the log. > > Isn't the host clock invisible to the guest anyway?
It isn't. Host clock is used by guest RTC. > > There could be asynchronous events that occur in non-cpu threads. > > For now these events are shutdown request and block task execution. > > They may "hide" following clock (or another one) events. That is why > > we process them until synchronous event (like clock, instructions > > execution, or checkpoint) is met. > > > > > > > Anyway, what does "can't proceed" mean? The coroutine yields because > > > it's waiting for I/O, but it is never reentered? Or is it hanging while > > > trying to acquire a lock? > > > > I've solved this problem by slightly modifying the queue. > > I haven't yet made BlockDriverState assignment to the request ids. > > Therefore aio_poll was temporarily replaced with usleep. > > Now execution starts and hangs at some random moment of OS loading. > > > > Here is the current version of blkreplay functions: > > > > static int coroutine_fn blkreplay_co_readv(BlockDriverState *bs, > > int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) > > { > > uint32_t reqid = request_id++; > > Request *req; > > req = block_request_insert(reqid, bs, qemu_coroutine_self()); > > bdrv_co_readv(bs->file->bs, sector_num, nb_sectors, qiov); > > > > if (replay_mode == REPLAY_MODE_RECORD) { > > replay_save_block_event(reqid); > > } else { > > assert(replay_mode == REPLAY_MODE_PLAY); > > qemu_coroutine_yield(); > > } > > block_request_remove(req); > > > > return 0; > > } > > > > void replay_run_block_event(uint32_t id) > > { > > Request *req; > > if (replay_mode == REPLAY_MODE_PLAY) { > > while (!(req = block_request_find(id))) { > > //aio_poll(bdrv_get_aio_context(req->bs), true); > > usleep(1); > > } > > How is this loop supposed to make any progress? This loop does not supposed to make any progress. It waits until block_request_insert call is added to the queue. > And I still don't understand why aio_poll() doesn't work and where it > hangs. aio_poll hangs if "req = block_request_insert(reqid, bs, qemu_coroutine_self());" line is executed after bdrv_co_readv. When bdrv_co_readv yields, replay_run_block_event has no information about pending request and cannot jump to its coroutine. Maybe I should implement aio_poll execution there to make progress in that case? > > qemu_coroutine_enter(req->co, NULL); > > } > > } Pavel Dovgalyuk