| Message ID | 20190819061843.28642-2-richardw.yang@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | migration/postcopy: unsentmap is not necessary | expand |
* Wei Yang (richardw.yang@linux.intel.com) wrote: > All pages, either partially sent or partially dirty, will be discarded in > postcopy_send_discard_bm_ram(), since we update the unsentmap to be > unsentmap = unsentmap | dirty in ram_postcopy_send_discard_bitmap(). > > This is not necessary to do discard when canonicalizing bitmap. And by > doing so, we separate the page discard into two individual steps: > > * canonicalize bitmap > * discard page > > Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Yes, I think when I originally wrote it, the set of pages that was discarded was different; I think it was actually the set of !unsent & dirty - i.e. only pages that had been sent and then redirtied; it later got reworked to include unsent pages as well - so this lot can be simplified. Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > migration/ram.c | 14 +------------- > 1 file changed, 1 insertion(+), 13 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index 35552c090b..075ddc468c 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -2928,7 +2928,7 @@ static int postcopy_each_ram_send_discard(MigrationState *ms) > } > > /** > - * postcopy_chunk_hostpages_pass: canocalize bitmap in hostpages > + * postcopy_chunk_hostpages_pass: canonicalize bitmap in hostpages > * > * Helper for postcopy_chunk_hostpages; it's called twice to > * canonicalize the two bitmaps, that are similar, but one is > @@ -2991,18 +2991,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, > host_ratio); > run_start = QEMU_ALIGN_UP(run_start, host_ratio); > > - /* Tell the destination to discard this page */ > - if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) { > - /* For the unsent_pass we: > - * discard partially sent pages > - * For the !unsent_pass (dirty) we: > - * discard partially dirty pages that were sent > - * (any partially sent pages were already discarded > - * by the previous unsent_pass) > - */ > - postcopy_discard_send_range(ms, fixup_start_addr, host_ratio); > - } > - > /* Clean up the bitmap */ > for (page = fixup_start_addr; > page < fixup_start_addr + host_ratio; page++) { > -- > 2.17.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
On Tue, Sep 24, 2019 at 11:02:08AM +0100, Dr. David Alan Gilbert wrote: >* Wei Yang (richardw.yang@linux.intel.com) wrote: >> All pages, either partially sent or partially dirty, will be discarded in >> postcopy_send_discard_bm_ram(), since we update the unsentmap to be >> unsentmap = unsentmap | dirty in ram_postcopy_send_discard_bitmap(). >> >> This is not necessary to do discard when canonicalizing bitmap. And by >> doing so, we separate the page discard into two individual steps: >> >> * canonicalize bitmap >> * discard page >> >> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> > >Yes, I think when I originally wrote it, the set of pages that was >discarded was different; I think it was actually the set of >!unsent & dirty - i.e. only pages that had been sent and then redirtied; >it later got reworked to include unsent pages as well - so this lot can >be simplified. > > Thanks for your time :-) > >Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > >> --- >> migration/ram.c | 14 +------------- >> 1 file changed, 1 insertion(+), 13 deletions(-) >> >> diff --git a/migration/ram.c b/migration/ram.c >> index 35552c090b..075ddc468c 100644 >> --- a/migration/ram.c >> +++ b/migration/ram.c >> @@ -2928,7 +2928,7 @@ static int postcopy_each_ram_send_discard(MigrationState *ms) >> } >> >> /** >> - * postcopy_chunk_hostpages_pass: canocalize bitmap in hostpages >> + * postcopy_chunk_hostpages_pass: canonicalize bitmap in hostpages >> * >> * Helper for postcopy_chunk_hostpages; it's called twice to >> * canonicalize the two bitmaps, that are similar, but one is >> @@ -2991,18 +2991,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, >> host_ratio); >> run_start = QEMU_ALIGN_UP(run_start, host_ratio); >> >> - /* Tell the destination to discard this page */ >> - if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) { >> - /* For the unsent_pass we: >> - * discard partially sent pages >> - * For the !unsent_pass (dirty) we: >> - * discard partially dirty pages that were sent >> - * (any partially sent pages were already discarded >> - * by the previous unsent_pass) >> - */ >> - postcopy_discard_send_range(ms, fixup_start_addr, host_ratio); >> - } >> - >> /* Clean up the bitmap */ >> for (page = fixup_start_addr; >> page < fixup_start_addr + host_ratio; page++) { >> -- >> 2.17.1 >> >-- >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff --git a/migration/ram.c b/migration/ram.c index 35552c090b..075ddc468c 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2928,7 +2928,7 @@ static int postcopy_each_ram_send_discard(MigrationState *ms) } /** - * postcopy_chunk_hostpages_pass: canocalize bitmap in hostpages + * postcopy_chunk_hostpages_pass: canonicalize bitmap in hostpages * * Helper for postcopy_chunk_hostpages; it's called twice to * canonicalize the two bitmaps, that are similar, but one is @@ -2991,18 +2991,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, host_ratio); run_start = QEMU_ALIGN_UP(run_start, host_ratio); - /* Tell the destination to discard this page */ - if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) { - /* For the unsent_pass we: - * discard partially sent pages - * For the !unsent_pass (dirty) we: - * discard partially dirty pages that were sent - * (any partially sent pages were already discarded - * by the previous unsent_pass) - */ - postcopy_discard_send_range(ms, fixup_start_addr, host_ratio); - } - /* Clean up the bitmap */ for (page = fixup_start_addr; page < fixup_start_addr + host_ratio; page++) {
All pages, either partially sent or partially dirty, will be discarded in postcopy_send_discard_bm_ram(), since we update the unsentmap to be unsentmap = unsentmap | dirty in ram_postcopy_send_discard_bitmap(). This is not necessary to do discard when canonicalizing bitmap. And by doing so, we separate the page discard into two individual steps: * canonicalize bitmap * discard page Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> --- migration/ram.c | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-)