On Mon, Aug 5, 2019 at 8:34 AM Wei Yang <richardw.y...@linux.intel.com> wrote: > > On Fri, Aug 02, 2019 at 06:18:41PM +0800, Ivan Ren wrote: > >From: Ivan Ren <ivan...@tencent.com> > > > >This patch fix a multifd migration bug in migration speed calculation, this > >problem can be reproduced as follows: > >1. start a vm and give a heavy memory write stress to prevent the vm be > > successfully migrated to destination > >2. begin a migration with multifd > >3. migrate for a long time [actually, this can be measured by transferred > >bytes] > >4. migrate cancel > >5. begin a new migration with multifd, the migration will directly run into > > migration_completion phase > > > >Reason as follows: > > > >Migration update bandwidth and s->threshold_size in function > >migration_update_counters after BUFFER_DELAY time: > > > > current_bytes = migration_total_bytes(s); > > transferred = current_bytes - s->iteration_initial_bytes; > > time_spent = current_time - s->iteration_start_time; > > bandwidth = (double)transferred / time_spent; > > s->threshold_size = bandwidth * s->parameters.downtime_limit; > > > >In multifd migration, migration_total_bytes function return > >qemu_ftell(s->to_dst_file) + ram_counters.multifd_bytes. > >s->iteration_initial_bytes will be initialized to 0 at every new migration, > >but ram_counters is a global variable, and history migration data will be > >accumulated. So if the ram_counters.multifd_bytes is big enough, it may lead > >pending_size >= s->threshold_size become false in migration_iteration_run > >after the first migration_update_counters. > > > >Signed-off-by: Ivan Ren <ivan...@tencent.com> > >Reviewed-by: Juan Quintela <quint...@redhat.com> > >Suggested-by: Wei Yang <richardw.y...@linux.intel.com> > >--- > >v2->v3: > >- fix the bug of update_iteration_initial_status function prototype > > > > Code looks good. Have you verified on this version?
Yes > BTW, you didn't address the multifd count in this patch, right? Yes. Currently multifd page count has no harm, so I think it's better to optimize it in a new patch to make things clearer. Thanks.
