On Wed, Jun 05, 2019 at 12:33:39PM +0200, Juan Quintela wrote: >Peter Xu <pet...@redhat.com> wrote: >> On Wed, Jun 05, 2019 at 04:52:07PM +0800, Wei Yang wrote: >>> On Wed, Jun 05, 2019 at 02:41:08PM +0800, Peter Xu wrote: >>> >On Wed, Jun 05, 2019 at 09:08:28AM +0800, Wei Yang wrote: >>> >> In case we gets a queued page, the order of block is interrupted. We may >>> >> not rely on the complete_round flag to say we have already searched the >>> >> whole blocks on the list. >>> >> >>> >> Signed-off-by: Wei Yang <richardw.y...@linux.intel.com> >>> >> --- >>> >> migration/ram.c | 6 ++++++ >>> >> 1 file changed, 6 insertions(+) >>> >> >>> >> diff --git a/migration/ram.c b/migration/ram.c >>> >> index d881981876..e9b40d636d 100644 >>> >> --- a/migration/ram.c >>> >> +++ b/migration/ram.c >>> >> @@ -2290,6 +2290,12 @@ static bool get_queued_page(RAMState *rs, >>> >> PageSearchStatus *pss) >>> >> */ >>> >> pss->block = block; >>> >> pss->page = offset >> TARGET_PAGE_BITS; >>> >> + >>> >> + /* >>> >> + * This unqueued page would break the "one round" check, even is >>> >> + * really rare. >>> > > > >> Ah I see your point, but I don't think there is a problem - note that >> complete_round will be reset for each ram_find_and_save_block(), so >> even if we have that iteration of ram_find_and_save_block() to return >> we'll still know we have dirty pages to migrate and in the next call >> we'll be fine, no? > >Reviewed-by: Juan Quintela <quint...@redhat.com> > >I *think* that peter is perhaps right, but it is not clear at all, and >it is easier to be safe. I think that the only case that this could >matter is if: >- all pages are clean (so complete_round will get as true) >- we went a queue_page request > >Is that possible? I am not completely sure after looking at the code. >It *could* be if the page that got queued is the last page remaining, >but ...... I fully agree that the case that _almost all_ pages are >clean and we get a request for a queued page is really rare, so it >should not matter in real life, but .... >
Agree >Later, Juan. -- Wei Yang Help you, Help me
