Elena Ufimtseva <elena.ufimts...@oracle.com> writes: > In multifd_send_sync_main we need to wait for channels_ready > before submitting sync packet as the threads may still be sending > their previous pages. > There is also no need to check for channels_ready in the loop > before the wait for sem_sync, next iteration of sending pages > or another sync will start with waiting for channels_ready > semaphore. > Changes to commit 90b3cec351996dd8ef4eb847ad38607812c5e7f5 > ("multifd: Fix the number of channels ready") > > Signed-off-by: Elena Ufimtseva <elena.ufimts...@oracle.com> > --- > migration/multifd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/migration/multifd.c b/migration/multifd.c > index 0f6b203877..e61e458151 100644 > --- a/migration/multifd.c > +++ b/migration/multifd.c > @@ -595,6 +595,7 @@ int multifd_send_sync_main(QEMUFile *f) > } > } > > + qemu_sem_wait(&multifd_send_state->channels_ready); > /* > * When using zero-copy, it's necessary to flush the pages before any of > * the pages can be sent again, so we'll make sure the new version of the > @@ -630,7 +631,6 @@ int multifd_send_sync_main(QEMUFile *f) > for (i = 0; i < migrate_multifd_channels(); i++) { > MultiFDSendParams *p = &multifd_send_state->params[i]; > > - qemu_sem_wait(&multifd_send_state->channels_ready); > trace_multifd_send_sync_main_wait(p->id); > qemu_sem_wait(&p->sem_sync);
Please take a look at the series I just sent. Basically, I think we should wait on 'sem' for the number of existing channels and not just once per sync. Otherwise I think we'd hit the same issue this patch is trying to fix when we loop into the n+1 channels. I think the assert(!p->pending_job) in patch 3 helps prove that's more appropriate. Let me know what you think. Thanks