Allow multifd to open file-backed channels. This will be used when
enabling the fixed-ram migration stream format which expects a
seekable transport.
The QIOChannel read and write methods will use the preadv/pwritev
versions which don't update the file offset at each call so we can
reuse the fd without re-opening for every channel.
Note that this is just setup code and multifd cannot yet make use of
the file channels.
Signed-off-by: Fabiano Rosas <farosas@suse.de>
For the upcoming support to the new 'fixed-ram' migration stream
format, we cannot use multifd packets because each write into the
ramblock section in the migration file is expected to contain only the
guest pages. They are written at their respective offsets relative to
the ramblock section header.
There is no space for the packet information and the expected gains
from the new approach come partly from being able to write the pages
sequentially without extraneous data in between.
The new format also doesn't need the packets and all necessary
information can be taken from the standard migration headers with some
(future) changes to multifd code.
Use the presence of the fixed-ram capability to decide whether to send
packets. For now this has no effect as fixed-ram cannot yet be enabled
with multifd.
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Implement the outgoing migration side for the 'fixed-ram' capability.
A bitmap is introduced to track which pages have been written in the
migration file. Pages are written at a fixed location for every
ramblock. Zero pages are ignored as they'd be zero in the destination
migration as well.
The migration stream is altered to put the dirty pages for a ramblock
after its header instead of having a sequential stream of pages that
follow the ramblock headers. Since all pages have a fixed location,
RAM_SAVE_FLAG_EOS is no longer generated on every migration iteration.
Without fixed-ram (current):
ramblock 1 header|ramblock 2 header|...|RAM_SAVE_FLAG_EOS|stream of
pages (iter 1)|RAM_SAVE_FLAG_EOS|stream of pages (iter 2)|...
With fixed-ram (new):
ramblock 1 header|ramblock 1 fixed-ram header|ramblock 1 pages (fixed
offsets)|ramblock 2 header|ramblock 2 fixed-ram header|ramblock 2
pages (fixed offsets)|...|RAM_SAVE_FLAG_EOS
where:
- ramblock header: the generic information for a ramblock, such as
idstr, used_len, etc.
- ramblock fixed-ram header: the new information added by this
feature: bitmap of pages written, bitmap size and offset of pages
in the migration file.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add a new migration capability 'fixed-ram'.
The core of the feature is to ensure that each ram page has a specific
offset in the resulting migration stream. The reason why we'd want
such behavior are two fold:
- When doing a 'fixed-ram' migration the resulting file will have a
bounded size, since pages which are dirtied multiple times will
always go to a fixed location in the file, rather than constantly
being added to a sequential stream. This eliminates cases where a vm
with, say, 1G of ram can result in a migration file that's 10s of
GBs, provided that the workload constantly redirties memory.
- It paves the way to implement DIRECT_IO-enabled save/restore of the
migration stream as the pages are ensured to be written at aligned
offsets.
For now, enabling the capability has no effect. The next couple of
patches implement the core funcionality.
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add a new capability to indicate whether the VM should be made to stop
prior to migration.
This allows QEMU to be more aggressive with dirty tracking
optimizations and allows the management layer to be explicit on
whether it expects the migration to be performed live.
Signed-off-by: Fabiano Rosas <farosas@suse.de>
These way we can make them atomic and use this functions from any
place. I also moved all functions that use rate_limit to
migration-stats.
Functions got renamed, they are not qemu_file anymore.
qemu_file_rate_limit -> migration_rate_exceeded
qemu_file_set_rate_limit -> migration_rate_set
qemu_file_get_rate_limit -> migration_rate_get
qemu_file_reset_rate_limit -> migration_rate_reset
qemu_file_acct_rate_limit -> migration_rate_account.
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-Id: <20230515195709.63843-6-quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
That the implementation does the check every 100 milliseconds is an
implementation detail that shouldn't be seen on the interfaz.
Notice that all callers of qemu_file_set_rate_limit() used the
division or pass 0, so this change is a NOP.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20230508130909.65420-4-quintela@redhat.com>
COLO is not listed as running state in migrate_is_running(), so, it's
theoretically possible to disable colo capability in COLO state and the
unexpected error in migration_iteration_finish() is reachable.
Let's disallow that in qmp_migrate_set_capabilities. Than the error
becomes absolutely unreachable: we can get into COLO state only with
enabled capability and can't disable it while we are in COLO state. So
substitute the error by simple assertion.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20230428194928.1426370-10-vsementsov@yandex-team.ru>
Signed-off-by: Juan Quintela <quintela@redhat.com>
colo_checkpoint_notify() is mostly used in colo.c. Outside we use it
once when x-checkpoint-delay migration parameter is set. So, let's
simplify the external API to only that function - notify COLO that
parameter was set. This make external API more robust and hides
implementation details from external callers. Also this helps us to
make COLO module optional in further patch (i.e. we are going to add
possibility not build the COLO module).
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Zhang Chen <chen.zhang@intel.com>
Message-Id: <20230428194928.1426370-3-vsementsov@yandex-team.ru>
Signed-off-by: Juan Quintela <quintela@redhat.com>
It is valid that params->has_block_bitmap_mapping is true and
params->block_bitmap_mapping is NULL. So we can't use the trick of
having a single function.
Move to two functions one for each value and the tests are fixed.
Fixes: b804b35b1c
migration: Create migrate_block_bitmap_mapping() function
Reported-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-Id: <20230503181036.14890-1-quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
We need to add a new flag to mean to flush at that point.
Notice that we still flush at the end of setup and at the end of
complete stages.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
---
Add missing qemu_fflush(), now it passes all tests always.
In the previous version, the check that changes the default value to
false got lost in some rebase. Get it back.
We used to flush all channels at the end of each RAM section
sent. That is not needed, so preparing to only flush after a full
iteration through all the RAM.
Default value of the property is false. But we return "true" in
migrate_multifd_flush_after_each_section() until we implement the code
in following patches.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
---
Rename each-iteration to after-each-section
Rename multifd-sync-after-each-section to
multifd-flush-after-each-section
Move to machine-8.0 (peter)
Notice that we changed the test of ->has_block_bitmap_mapping
for the test that block_bitmap_mapping is not NULL.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
Make it return const (vladimir)
This makes the function more regular with everything else.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Once there, make it more regular and remove the need for
MigrationState parameter.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Instead of print it to STDERR, bring the error upwards so that it can be
reported via QMP responses.
E.g.:
{ "execute": "migrate-set-capabilities" ,
"arguments": { "capabilities":
[ { "capability": "postcopy-ram", "state": true } ] } }
{ "error":
{ "class": "GenericError",
"desc": "Postcopy is not supported: Host backend files need to be TMPFS
or HUGETLBFS only" } }
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Once there, rename it to migrate_tls() and make it return bool for
consistency.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
Fix typos found by fabiano
Since the introduction of multifd, it's possible to perform a multifd
migration and finish it using postcopy.
A bug introduced by yank (fixed on cfc3bcf373) was previously preventing
a successful use of this migration scenario, and now thing should be
working on most scenarios.
But since there is not enough testing/support nor any reported users for
this scenario, we should disable this combination before it may cause any
problems for users.
Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
To be consistent with every other parameter, rename to
migrate_block_incremental().
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Once that we are there, we rename the function to migrate_return_path()
to be consistent with all other capabilities.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Once that we are there, we rename the function to migrate_block()
to be consistent with all other capabilities.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Once that we are there, we rename the function to migrate_xbzrle()
to be consistent with all other capabilities.
We change the type to return bool also for consistency.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Once that we are there, we rename the function to
migrate_zero_copy_send() to be consistent with all other capabilities.
We can remove the CONFIG_LINUX guard. We already check that we can't
setup this capability in migrate_caps_check().
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Once that we are there, we rename the function to migrate_multifd()
to be consistent with all other capabilities.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Once that we are there, we rename the function to migrate_events()
to be consistent with all other capabilities.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
