Re: [Qemu-devel] [PATCH 10/17] migration: create ram_multifd_page

[Dr. David Alan Gilbert]

* Juan Quintela (quint...@redhat.com) wrote:
> "Dr. David Alan Gilbert"  wrote:
> > * Juan Quintela (quint...@redhat.com) wrote:
> >> The function still don't use multifd, but we have simplified
> >> ram_save_page, xbzrle and RDMA stuff is gone.  We have added a new
> >> counter and a new flag for this type of pages.
> 
> 
> >> +static int ram_multifd_page(QEMUFile *f, PageSearchStatus *pss,
> >> +bool last_stage, uint64_t *bytes_transferred)
> >> +{
> >> +int pages;
> >> +uint8_t *p;
> >> +RAMBlock *block = pss->block;
> >> +ram_addr_t offset = pss->offset;
> >> +
> >> +p = block->host + offset;
> >> +
> >> +if (block == last_sent_block) {
> >> +offset |= RAM_SAVE_FLAG_CONTINUE;
> >> +}
> >> +pages = save_zero_page(f, block, offset, p, bytes_transferred);
> >> +if (pages == -1) {
> >> +*bytes_transferred +=
> >> +save_page_header(f, block, offset | 
> >> RAM_SAVE_FLAG_MULTIFD_PAGE);
> >> +qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
> >> +*bytes_transferred += TARGET_PAGE_SIZE;
> >> +pages = 1;
> >> +acct_info.norm_pages++;
> >> +acct_info.multifd_pages++;
> >> +}
> >> +
> >> +return pages;
> >> +}
> >> +
> >>  static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
> >>  ram_addr_t offset)
> >>  {
> >> @@ -1427,6 +1461,8 @@ static int ram_save_target_page(MigrationState *ms, 
> >> QEMUFile *f,
> >>  res = ram_save_compressed_page(f, pss,
> >> last_stage,
> >> bytes_transferred);
> >> +} else if (migrate_use_multifd()) {
> >> +res = ram_multifd_page(f, pss, last_stage, bytes_transferred);
> >
> > I'm curious whether it's best to pick the destination fd at this level or 
> > one level
> > higher; for example would it be good to keep all the components of a
> > host page or huge
> > page together on the same fd? If so then it would be best to pick the fd
> > at ram_save_host_page level.
> 
> my plan here would be to change the migration code to be able to call
> with a bigger sizes, not page by page, and then the problem is solved by
> itself?

Yes it might be, but you may have to be careful to keep all your FDs busy;
for example, imagine that we're using huge pages, and you try and stuff
an entire hugepage down one FD, for 2MB hugepages that's about half of the
write buffer (tcp-wmem?) so there's a fair chance it'll block.  But thereagain
I think it's probably the right thing to do as long as you can get
different pages down different FDs.

Dave

> Later, Juan.
> 
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK

Re: [Qemu-devel] [PATCH 10/17] migration: create ram_multifd_page

[Juan Quintela]

"Dr. David Alan Gilbert"  wrote:
> * Juan Quintela (quint...@redhat.com) wrote:
>> The function still don't use multifd, but we have simplified
>> ram_save_page, xbzrle and RDMA stuff is gone.  We have added a new
>> counter and a new flag for this type of pages.


>> +static int ram_multifd_page(QEMUFile *f, PageSearchStatus *pss,
>> +bool last_stage, uint64_t *bytes_transferred)
>> +{
>> +int pages;
>> +uint8_t *p;
>> +RAMBlock *block = pss->block;
>> +ram_addr_t offset = pss->offset;
>> +
>> +p = block->host + offset;
>> +
>> +if (block == last_sent_block) {
>> +offset |= RAM_SAVE_FLAG_CONTINUE;
>> +}
>> +pages = save_zero_page(f, block, offset, p, bytes_transferred);
>> +if (pages == -1) {
>> +*bytes_transferred +=
>> +save_page_header(f, block, offset | RAM_SAVE_FLAG_MULTIFD_PAGE);
>> +qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
>> +*bytes_transferred += TARGET_PAGE_SIZE;
>> +pages = 1;
>> +acct_info.norm_pages++;
>> +acct_info.multifd_pages++;
>> +}
>> +
>> +return pages;
>> +}
>> +
>>  static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
>>  ram_addr_t offset)
>>  {
>> @@ -1427,6 +1461,8 @@ static int ram_save_target_page(MigrationState *ms, 
>> QEMUFile *f,
>>  res = ram_save_compressed_page(f, pss,
>> last_stage,
>> bytes_transferred);
>> +} else if (migrate_use_multifd()) {
>> +res = ram_multifd_page(f, pss, last_stage, bytes_transferred);
>
> I'm curious whether it's best to pick the destination fd at this level or one 
> level
> higher; for example would it be good to keep all the components of a
> host page or huge
> page together on the same fd? If so then it would be best to pick the fd
> at ram_save_host_page level.

my plan here would be to change the migration code to be able to call
with a bigger sizes, not page by page, and then the problem is solved by
itself?

Later, Juan.

Re: [Qemu-devel] [PATCH 10/17] migration: create ram_multifd_page

[Dr. David Alan Gilbert]

* Juan Quintela (quint...@redhat.com) wrote:
> The function still don't use multifd, but we have simplified
> ram_save_page, xbzrle and RDMA stuff is gone.  We have added a new
> counter and a new flag for this type of pages.
> 
> Signed-off-by: Juan Quintela 

Reviewed-by: Dr. David Alan Gilbert 

Dave

> ---
>  hmp.c |  2 ++
>  include/migration/migration.h |  1 +
>  migration/migration.c |  1 +
>  migration/ram.c   | 51 
> ++-
>  qapi-schema.json  |  4 +++-
>  5 files changed, 57 insertions(+), 2 deletions(-)
> 
> diff --git a/hmp.c b/hmp.c
> index e579766..76bc8c7 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -222,6 +222,8 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
>  monitor_printf(mon, "postcopy request count: %" PRIu64 "\n",
> info->ram->postcopy_requests);
>  }
> +monitor_printf(mon, "multifd: %" PRIu64 " pages\n",
> +   info->ram->multifd);
>  }
> 
>  if (info->has_disk) {
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index 3989bd6..b3e4f31 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -282,6 +282,7 @@ uint64_t xbzrle_mig_pages_transferred(void);
>  uint64_t xbzrle_mig_pages_overflow(void);
>  uint64_t xbzrle_mig_pages_cache_miss(void);
>  double xbzrle_mig_cache_miss_rate(void);
> +uint64_t multifd_mig_pages_transferred(void);
> 
>  void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
>  void ram_debug_dump_bitmap(unsigned long *todump, bool expected);
> diff --git a/migration/migration.c b/migration/migration.c
> index ab48f06..1d62b91 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -652,6 +652,7 @@ static void populate_ram_info(MigrationInfo *info, 
> MigrationState *s)
>  info->ram->mbps = s->mbps;
>  info->ram->dirty_sync_count = s->dirty_sync_count;
>  info->ram->postcopy_requests = s->postcopy_requests;
> +info->ram->multifd = multifd_mig_pages_transferred();
> 
>  if (s->state != MIGRATION_STATUS_COMPLETED) {
>  info->ram->remaining = ram_bytes_remaining();
> diff --git a/migration/ram.c b/migration/ram.c
> index 5ad7cb3..c71929e 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -61,6 +61,7 @@ static uint64_t bitmap_sync_count;
>  #define RAM_SAVE_FLAG_XBZRLE   0x40
>  /* 0x80 is reserved in migration.h start with 0x100 next */
>  #define RAM_SAVE_FLAG_COMPRESS_PAGE0x100
> +#define RAM_SAVE_FLAG_MULTIFD_PAGE 0x200
> 
>  static uint8_t *ZERO_TARGET_PAGE;
> 
> @@ -141,6 +142,7 @@ typedef struct AccountingInfo {
>  uint64_t dup_pages;
>  uint64_t skipped_pages;
>  uint64_t norm_pages;
> +uint64_t multifd_pages;
>  uint64_t iterations;
>  uint64_t xbzrle_bytes;
>  uint64_t xbzrle_pages;
> @@ -211,6 +213,11 @@ uint64_t xbzrle_mig_pages_overflow(void)
>  return acct_info.xbzrle_overflows;
>  }
> 
> +uint64_t multifd_mig_pages_transferred(void)
> +{
> +return acct_info.multifd_pages;
> +}
> +
>  /* This is the last block that we have visited serching for dirty pages
>   */
>  static RAMBlock *last_seen_block;
> @@ -990,6 +997,33 @@ static int ram_save_page(QEMUFile *f, PageSearchStatus 
> *pss,
>  return pages;
>  }
> 
> +static int ram_multifd_page(QEMUFile *f, PageSearchStatus *pss,
> +bool last_stage, uint64_t *bytes_transferred)
> +{
> +int pages;
> +uint8_t *p;
> +RAMBlock *block = pss->block;
> +ram_addr_t offset = pss->offset;
> +
> +p = block->host + offset;
> +
> +if (block == last_sent_block) {
> +offset |= RAM_SAVE_FLAG_CONTINUE;
> +}
> +pages = save_zero_page(f, block, offset, p, bytes_transferred);
> +if (pages == -1) {
> +*bytes_transferred +=
> +save_page_header(f, block, offset | RAM_SAVE_FLAG_MULTIFD_PAGE);
> +qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
> +*bytes_transferred += TARGET_PAGE_SIZE;
> +pages = 1;
> +acct_info.norm_pages++;
> +acct_info.multifd_pages++;
> +}
> +
> +return pages;
> +}
> +
>  static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
>  ram_addr_t offset)
>  {
> @@ -1427,6 +1461,8 @@ static int ram_save_target_page(MigrationState *ms, 
> QEMUFile *f,
>  res = ram_save_compressed_page(f, pss,
> last_stage,
> bytes_transferred);
> +} else if (migrate_use_multifd()) {
> +res = ram_multifd_page(f, pss, last_stage, bytes_transferred);
>  } else {
>  res = ram_save_page(f, pss, last_stage,
>  bytes_transferred);
> @@ -2678,6 +2714,10 @@ static int ram_load(QEMUFile *f, void *opaque, int 
> 

Re: [Qemu-devel] [PATCH 10/17] migration: create ram_multifd_page

[Dr. David Alan Gilbert]

* Juan Quintela (quint...@redhat.com) wrote:
> "Dr. David Alan Gilbert"  wrote:
> > * Juan Quintela (quint...@redhat.com) wrote:
> >> The function still don't use multifd, but we have simplified
> >> ram_save_page, xbzrle and RDMA stuff is gone.  We have added a new
> >> counter and a new flag for this type of pages.
> >> 
> >> Signed-off-by: Juan Quintela 
> 
> >> --- a/migration/ram.c
> >> +++ b/migration/ram.c
> >> @@ -61,6 +61,7 @@ static uint64_t bitmap_sync_count;
> >>  #define RAM_SAVE_FLAG_XBZRLE   0x40
> >>  /* 0x80 is reserved in migration.h start with 0x100 next */
> >>  #define RAM_SAVE_FLAG_COMPRESS_PAGE0x100
> >> +#define RAM_SAVE_FLAG_MULTIFD_PAGE 0x200
> >
> > I think a similar reminder from the last iteration of this patch;
> > I think we're out of bits here - I'm not sure if 0x200 is even
> > available.
> 
> In previous iteration, I used *two* bits.  As per your recomendation, I
> "reused" and old one for doing the synchronization.

Hmm OK, but that's still the last free bit; given TARGET_PAGE_BITS 10
on 3 targets, we can't use 0x400.
I guess the next user of a new bit will need to use RAM_SAVE_FLAG_FULL
which has never really been used and that will have to be some
magic that caused another block of bits to be read.

Dave

> 
> Later, Juan.
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK

Re: [Qemu-devel] [PATCH 10/17] migration: create ram_multifd_page

[Juan Quintela]

"Dr. David Alan Gilbert"  wrote:
> * Juan Quintela (quint...@redhat.com) wrote:
>> The function still don't use multifd, but we have simplified
>> ram_save_page, xbzrle and RDMA stuff is gone.  We have added a new
>> counter and a new flag for this type of pages.
>> 
>> Signed-off-by: Juan Quintela 

>> --- a/migration/ram.c
>> +++ b/migration/ram.c
>> @@ -61,6 +61,7 @@ static uint64_t bitmap_sync_count;
>>  #define RAM_SAVE_FLAG_XBZRLE   0x40
>>  /* 0x80 is reserved in migration.h start with 0x100 next */
>>  #define RAM_SAVE_FLAG_COMPRESS_PAGE0x100
>> +#define RAM_SAVE_FLAG_MULTIFD_PAGE 0x200
>
> I think a similar reminder from the last iteration of this patch;
> I think we're out of bits here - I'm not sure if 0x200 is even
> available.

In previous iteration, I used *two* bits.  As per your recomendation, I
"reused" and old one for doing the synchronization.


Later, Juan.

Re: [Qemu-devel] [PATCH 10/17] migration: create ram_multifd_page

[Dr. David Alan Gilbert]

* Juan Quintela (quint...@redhat.com) wrote:
> The function still don't use multifd, but we have simplified
> ram_save_page, xbzrle and RDMA stuff is gone.  We have added a new
> counter and a new flag for this type of pages.
> 
> Signed-off-by: Juan Quintela 
> ---
>  hmp.c |  2 ++
>  include/migration/migration.h |  1 +
>  migration/migration.c |  1 +
>  migration/ram.c   | 51 
> ++-
>  qapi-schema.json  |  4 +++-
>  5 files changed, 57 insertions(+), 2 deletions(-)
> 
> diff --git a/hmp.c b/hmp.c
> index e579766..76bc8c7 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -222,6 +222,8 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
>  monitor_printf(mon, "postcopy request count: %" PRIu64 "\n",
> info->ram->postcopy_requests);
>  }
> +monitor_printf(mon, "multifd: %" PRIu64 " pages\n",
> +   info->ram->multifd);
>  }
> 
>  if (info->has_disk) {
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index 3989bd6..b3e4f31 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -282,6 +282,7 @@ uint64_t xbzrle_mig_pages_transferred(void);
>  uint64_t xbzrle_mig_pages_overflow(void);
>  uint64_t xbzrle_mig_pages_cache_miss(void);
>  double xbzrle_mig_cache_miss_rate(void);
> +uint64_t multifd_mig_pages_transferred(void);
> 
>  void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
>  void ram_debug_dump_bitmap(unsigned long *todump, bool expected);
> diff --git a/migration/migration.c b/migration/migration.c
> index ab48f06..1d62b91 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -652,6 +652,7 @@ static void populate_ram_info(MigrationInfo *info, 
> MigrationState *s)
>  info->ram->mbps = s->mbps;
>  info->ram->dirty_sync_count = s->dirty_sync_count;
>  info->ram->postcopy_requests = s->postcopy_requests;
> +info->ram->multifd = multifd_mig_pages_transferred();
> 
>  if (s->state != MIGRATION_STATUS_COMPLETED) {
>  info->ram->remaining = ram_bytes_remaining();
> diff --git a/migration/ram.c b/migration/ram.c
> index 5ad7cb3..c71929e 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -61,6 +61,7 @@ static uint64_t bitmap_sync_count;
>  #define RAM_SAVE_FLAG_XBZRLE   0x40
>  /* 0x80 is reserved in migration.h start with 0x100 next */
>  #define RAM_SAVE_FLAG_COMPRESS_PAGE0x100
> +#define RAM_SAVE_FLAG_MULTIFD_PAGE 0x200

I think a similar reminder from the last iteration of this patch;
I think we're out of bits here - I'm not sure if 0x200 is even
available.

>  static uint8_t *ZERO_TARGET_PAGE;
> 
> @@ -141,6 +142,7 @@ typedef struct AccountingInfo {
>  uint64_t dup_pages;
>  uint64_t skipped_pages;
>  uint64_t norm_pages;
> +uint64_t multifd_pages;
>  uint64_t iterations;
>  uint64_t xbzrle_bytes;
>  uint64_t xbzrle_pages;
> @@ -211,6 +213,11 @@ uint64_t xbzrle_mig_pages_overflow(void)
>  return acct_info.xbzrle_overflows;
>  }
> 
> +uint64_t multifd_mig_pages_transferred(void)
> +{
> +return acct_info.multifd_pages;
> +}
> +
>  /* This is the last block that we have visited serching for dirty pages
>   */
>  static RAMBlock *last_seen_block;
> @@ -990,6 +997,33 @@ static int ram_save_page(QEMUFile *f, PageSearchStatus 
> *pss,
>  return pages;
>  }
> 
> +static int ram_multifd_page(QEMUFile *f, PageSearchStatus *pss,
> +bool last_stage, uint64_t *bytes_transferred)
> +{
> +int pages;
> +uint8_t *p;
> +RAMBlock *block = pss->block;
> +ram_addr_t offset = pss->offset;
> +
> +p = block->host + offset;
> +
> +if (block == last_sent_block) {
> +offset |= RAM_SAVE_FLAG_CONTINUE;
> +}
> +pages = save_zero_page(f, block, offset, p, bytes_transferred);
> +if (pages == -1) {
> +*bytes_transferred +=
> +save_page_header(f, block, offset | RAM_SAVE_FLAG_MULTIFD_PAGE);
> +qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
> +*bytes_transferred += TARGET_PAGE_SIZE;
> +pages = 1;
> +acct_info.norm_pages++;
> +acct_info.multifd_pages++;
> +}
> +
> +return pages;
> +}
> +
>  static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
>  ram_addr_t offset)
>  {
> @@ -1427,6 +1461,8 @@ static int ram_save_target_page(MigrationState *ms, 
> QEMUFile *f,
>  res = ram_save_compressed_page(f, pss,
> last_stage,
> bytes_transferred);
> +} else if (migrate_use_multifd()) {
> +res = ram_multifd_page(f, pss, last_stage, bytes_transferred);

I'm curious whether it's best to pick the destination fd at this level or one 
level
higher; for example would it be good to keep all the 

[Qemu-devel] [PATCH 10/17] migration: create ram_multifd_page

[Juan Quintela]

The function still don't use multifd, but we have simplified
ram_save_page, xbzrle and RDMA stuff is gone.  We have added a new
counter and a new flag for this type of pages.

Signed-off-by: Juan Quintela 
---
 hmp.c |  2 ++
 include/migration/migration.h |  1 +
 migration/migration.c |  1 +
 migration/ram.c   | 51 ++-
 qapi-schema.json  |  4 +++-
 5 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/hmp.c b/hmp.c
index e579766..76bc8c7 100644
--- a/hmp.c
+++ b/hmp.c
@@ -222,6 +222,8 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
 monitor_printf(mon, "postcopy request count: %" PRIu64 "\n",
info->ram->postcopy_requests);
 }
+monitor_printf(mon, "multifd: %" PRIu64 " pages\n",
+   info->ram->multifd);
 }

 if (info->has_disk) {
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 3989bd6..b3e4f31 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -282,6 +282,7 @@ uint64_t xbzrle_mig_pages_transferred(void);
 uint64_t xbzrle_mig_pages_overflow(void);
 uint64_t xbzrle_mig_pages_cache_miss(void);
 double xbzrle_mig_cache_miss_rate(void);
+uint64_t multifd_mig_pages_transferred(void);

 void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
 void ram_debug_dump_bitmap(unsigned long *todump, bool expected);
diff --git a/migration/migration.c b/migration/migration.c
index ab48f06..1d62b91 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -652,6 +652,7 @@ static void populate_ram_info(MigrationInfo *info, 
MigrationState *s)
 info->ram->mbps = s->mbps;
 info->ram->dirty_sync_count = s->dirty_sync_count;
 info->ram->postcopy_requests = s->postcopy_requests;
+info->ram->multifd = multifd_mig_pages_transferred();

 if (s->state != MIGRATION_STATUS_COMPLETED) {
 info->ram->remaining = ram_bytes_remaining();
diff --git a/migration/ram.c b/migration/ram.c
index 5ad7cb3..c71929e 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -61,6 +61,7 @@ static uint64_t bitmap_sync_count;
 #define RAM_SAVE_FLAG_XBZRLE   0x40
 /* 0x80 is reserved in migration.h start with 0x100 next */
 #define RAM_SAVE_FLAG_COMPRESS_PAGE0x100
+#define RAM_SAVE_FLAG_MULTIFD_PAGE 0x200

 static uint8_t *ZERO_TARGET_PAGE;

@@ -141,6 +142,7 @@ typedef struct AccountingInfo {
 uint64_t dup_pages;
 uint64_t skipped_pages;
 uint64_t norm_pages;
+uint64_t multifd_pages;
 uint64_t iterations;
 uint64_t xbzrle_bytes;
 uint64_t xbzrle_pages;
@@ -211,6 +213,11 @@ uint64_t xbzrle_mig_pages_overflow(void)
 return acct_info.xbzrle_overflows;
 }

+uint64_t multifd_mig_pages_transferred(void)
+{
+return acct_info.multifd_pages;
+}
+
 /* This is the last block that we have visited serching for dirty pages
  */
 static RAMBlock *last_seen_block;
@@ -990,6 +997,33 @@ static int ram_save_page(QEMUFile *f, PageSearchStatus 
*pss,
 return pages;
 }

+static int ram_multifd_page(QEMUFile *f, PageSearchStatus *pss,
+bool last_stage, uint64_t *bytes_transferred)
+{
+int pages;
+uint8_t *p;
+RAMBlock *block = pss->block;
+ram_addr_t offset = pss->offset;
+
+p = block->host + offset;
+
+if (block == last_sent_block) {
+offset |= RAM_SAVE_FLAG_CONTINUE;
+}
+pages = save_zero_page(f, block, offset, p, bytes_transferred);
+if (pages == -1) {
+*bytes_transferred +=
+save_page_header(f, block, offset | RAM_SAVE_FLAG_MULTIFD_PAGE);
+qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
+*bytes_transferred += TARGET_PAGE_SIZE;
+pages = 1;
+acct_info.norm_pages++;
+acct_info.multifd_pages++;
+}
+
+return pages;
+}
+
 static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
 ram_addr_t offset)
 {
@@ -1427,6 +1461,8 @@ static int ram_save_target_page(MigrationState *ms, 
QEMUFile *f,
 res = ram_save_compressed_page(f, pss,
last_stage,
bytes_transferred);
+} else if (migrate_use_multifd()) {
+res = ram_multifd_page(f, pss, last_stage, bytes_transferred);
 } else {
 res = ram_save_page(f, pss, last_stage,
 bytes_transferred);
@@ -2678,6 +2714,10 @@ static int ram_load(QEMUFile *f, void *opaque, int 
version_id)
 if (!migrate_use_compression()) {
 invalid_flags |= RAM_SAVE_FLAG_COMPRESS_PAGE;
 }
+
+if (!migrate_use_multifd()) {
+invalid_flags |= RAM_SAVE_FLAG_MULTIFD_PAGE;
+}
 /* This RCU critical section can be very long running.
  * When RCU reclaims in the code start to become numerous,
  * it will be necessary to reduce the