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Re: [Qemu-block] [Qemu-devel] [PATCH v10 05/12] migration: introduce pos
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH v10 05/12] migration: introduce postcopy-only pending |
Date: |
Tue, 13 Mar 2018 12:17:46 +0000 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
* John Snow (address@hidden) wrote:
>
>
> On 03/12/2018 11:30 AM, Dr. David Alan Gilbert wrote:
> > * Vladimir Sementsov-Ogievskiy (address@hidden) wrote:
> >> There would be savevm states (dirty-bitmap) which can migrate only in
> >> postcopy stage. The corresponding pending is introduced here.
> >>
> >> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> >> ---
> >> include/migration/register.h | 17 +++++++++++++++--
> >> migration/savevm.h | 5 +++--
> >> hw/s390x/s390-stattrib.c | 7 ++++---
> >> migration/block.c | 7 ++++---
> >> migration/migration.c | 16 +++++++++-------
> >> migration/ram.c | 9 +++++----
> >> migration/savevm.c | 13 ++++++++-----
> >> migration/trace-events | 2 +-
> >> 8 files changed, 49 insertions(+), 27 deletions(-)
> >>
> >> diff --git a/include/migration/register.h b/include/migration/register.h
> >> index f4f7bdc177..9436a87678 100644
> >> --- a/include/migration/register.h
> >> +++ b/include/migration/register.h
> >> @@ -37,8 +37,21 @@ typedef struct SaveVMHandlers {
> >> int (*save_setup)(QEMUFile *f, void *opaque);
> >> void (*save_live_pending)(QEMUFile *f, void *opaque,
> >> uint64_t threshold_size,
> >> - uint64_t *non_postcopiable_pending,
> >> - uint64_t *postcopiable_pending);
> >> + uint64_t *res_precopy_only,
> >> + uint64_t *res_compatible,
> >> + uint64_t *res_postcopy_only);
> >> + /* Note for save_live_pending:
> >> + * - res_precopy_only is for data which must be migrated in precopy
> >> phase
> >> + * or in stopped state, in other words - before target vm start
> >> + * - res_compatible is for data which may be migrated in any phase
> >> + * - res_postcopy_only is for data which must be migrated in postcopy
> >> phase
> >> + * or in stopped state, in other words - after source vm stop
> >> + *
> >> + * Sum of res_postcopy_only, res_compatible and res_postcopy_only is
> >> the
> >> + * whole amount of pending data.
> >> + */
> >> +
> >> +
> >> LoadStateHandler *load_state;
> >> int (*load_setup)(QEMUFile *f, void *opaque);
> >> int (*load_cleanup)(void *opaque);
> >> diff --git a/migration/savevm.h b/migration/savevm.h
> >> index 295c4a1f2c..cf4f0d37ca 100644
> >> --- a/migration/savevm.h
> >> +++ b/migration/savevm.h
> >> @@ -38,8 +38,9 @@ void qemu_savevm_state_complete_postcopy(QEMUFile *f);
> >> int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only,
> >> bool inactivate_disks);
> >> void qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size,
> >> - uint64_t *res_non_postcopiable,
> >> - uint64_t *res_postcopiable);
> >> + uint64_t *res_precopy_only,
> >> + uint64_t *res_compatible,
> >> + uint64_t *res_postcopy_only);
> >> void qemu_savevm_send_ping(QEMUFile *f, uint32_t value);
> >> void qemu_savevm_send_open_return_path(QEMUFile *f);
> >> int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t
> >> len);
> >> diff --git a/hw/s390x/s390-stattrib.c b/hw/s390x/s390-stattrib.c
> >> index 2902f54f11..dd3fbfd1eb 100644
> >> --- a/hw/s390x/s390-stattrib.c
> >> +++ b/hw/s390x/s390-stattrib.c
> >> @@ -183,15 +183,16 @@ static int cmma_save_setup(QEMUFile *f, void *opaque)
> >> }
> >>
> >> static void cmma_save_pending(QEMUFile *f, void *opaque, uint64_t
> >> max_size,
> >> - uint64_t *non_postcopiable_pending,
> >> - uint64_t *postcopiable_pending)
> >> + uint64_t *res_precopy_only,
> >> + uint64_t *res_compatible,
> >> + uint64_t *res_postcopy_only)
> >> {
> >> S390StAttribState *sas = S390_STATTRIB(opaque);
> >> S390StAttribClass *sac = S390_STATTRIB_GET_CLASS(sas);
> >> long long res = sac->get_dirtycount(sas);
> >>
> >> if (res >= 0) {
> >> - *non_postcopiable_pending += res;
> >> + *res_precopy_only += res;
> >> }
> >> }
> >>
> >> diff --git a/migration/block.c b/migration/block.c
> >> index 1f03946797..5652ca3337 100644
> >> --- a/migration/block.c
> >> +++ b/migration/block.c
> >> @@ -866,8 +866,9 @@ static int block_save_complete(QEMUFile *f, void
> >> *opaque)
> >> }
> >>
> >> static void block_save_pending(QEMUFile *f, void *opaque, uint64_t
> >> max_size,
> >> - uint64_t *non_postcopiable_pending,
> >> - uint64_t *postcopiable_pending)
> >> + uint64_t *res_precopy_only,
> >> + uint64_t *res_compatible,
> >> + uint64_t *res_postcopy_only)
> >> {
> >> /* Estimate pending number of bytes to send */
> >> uint64_t pending;
> >> @@ -888,7 +889,7 @@ static void block_save_pending(QEMUFile *f, void
> >> *opaque, uint64_t max_size,
> >>
> >> DPRINTF("Enter save live pending %" PRIu64 "\n", pending);
> >> /* We don't do postcopy */
> >> - *non_postcopiable_pending += pending;
> >> + *res_precopy_only += pending;
> >> }
> >>
> >> static int block_load(QEMUFile *f, void *opaque, int version_id)
> >> diff --git a/migration/migration.c b/migration/migration.c
> >> index c99a4e62d7..3beedd676e 100644
> >> --- a/migration/migration.c
> >> +++ b/migration/migration.c
> >> @@ -2215,21 +2215,23 @@ typedef enum {
> >> */
> >> static MigIterateState migration_iteration_run(MigrationState *s)
> >> {
> >> - uint64_t pending_size, pend_post, pend_nonpost;
> >> + uint64_t pending_size, pend_pre, pend_compat, pend_post;
> >> bool in_postcopy = s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE;
> >>
> >> - qemu_savevm_state_pending(s->to_dst_file, s->threshold_size,
> >> - &pend_nonpost, &pend_post);
> >> - pending_size = pend_nonpost + pend_post;
> >> + qemu_savevm_state_pending(s->to_dst_file, s->threshold_size,
> >> &pend_pre,
> >> + &pend_compat, &pend_post);
> >> + pending_size = pend_pre + pend_compat + pend_post;
> >>
> >> trace_migrate_pending(pending_size, s->threshold_size,
> >> - pend_post, pend_nonpost);
> >> + pend_pre, pend_compat, pend_post);
> >>
> >> if (pending_size && pending_size >= s->threshold_size) {
> >> /* Still a significant amount to transfer */
> >> if (migrate_postcopy() && !in_postcopy &&
> >> - pend_nonpost <= s->threshold_size &&
> >> - atomic_read(&s->start_postcopy)) {
> >> + pend_pre <= s->threshold_size &&
> >> + (atomic_read(&s->start_postcopy) ||
> >> + (pend_pre + pend_compat <= s->threshold_size)))
> >
> > This change does something different from the description;
> > it causes a postcopy_start even if the user never ran the postcopy-start
> > command; so sorry, we can't do that; because postcopy for RAM is
> > something that users can enable but only switch into when they've given
> > up on it completing normally.
> >
> > However, I guess that leaves you with a problem; which is what happens
> > to the system when you've run out of pend_pre+pend_compat but can't
> > complete because pend_post is non-0; so I don't know the answer to that.
> >
> > Dave
> >
>
> I'm willing to pull the bitmap related changes into my tree for 2.12,
> but it would be _really_ nice to have this patchset in 2.12 -- is there
> anything we can do to get this into the migration queue?
>
> I'm afraid I don't know what the right answer here is either, so I can't
> fix this up myself and I imagine Vladimir will need some feedback from
> you to change this design.
Well I'm good with everything except the change in semantics for
existing migration; we can't do that because it can break existing users.
> Are we -hosed- ?
Dave
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, Dr. David Alan Gilbert, 2018/03/12
- Re: [Qemu-block] [Qemu-devel] [PATCH v10 05/12] migration: introduce postcopy-only pending, John Snow, 2018/03/13
- Re: [Qemu-block] [Qemu-devel] [PATCH v10 05/12] migration: introduce postcopy-only pending,
Dr. David Alan Gilbert <=
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, Vladimir Sementsov-Ogievskiy, 2018/03/13
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, Dr. David Alan Gilbert, 2018/03/13
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, Vladimir Sementsov-Ogievskiy, 2018/03/13
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, Vladimir Sementsov-Ogievskiy, 2018/03/13
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, Dr. David Alan Gilbert, 2018/03/13
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, Vladimir Sementsov-Ogievskiy, 2018/03/13
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, John Snow, 2018/03/13
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, Vladimir Sementsov-Ogievskiy, 2018/03/13
- Re: [Qemu-block] [PATCH v10 05/12] migration: introduce postcopy-only pending, John Snow, 2018/03/13