The preempt mode postcopy has been introduced for a while. From latency
POV, it should always win the vanilla postcopy.
However there's one thing missing when preempt mode is enabled right now,
which is the spatial locality hint when there're page requests from the
destination side.
In vanilla postcopy, as long as a page request was unqueued, it will update
the PSS of the precopy background stream, so that after a page request the
background thread will move the pages after whatever was requested. It's
pretty much a natural behavior when there's only one channel anyway, and
one scanner to send the pages.
Preempt mode didn't follow that, because preempt mode has its own channel
and its own PSS (which doesn't linearly scan the guest memory, but
dedicated to resolve page requested from destination). So the page request
process and the background migration process are completely separate.
This patch adds the hint explicitly for preempt mode. With that, whenever
the preempt mode receives a page request on the source, it will service the
remote page fault in the return path, then it'll provide a hint to the
background thread so that we'll start sending the pages right after the
requested ones in the background, assuming the follow up pages have a
higher chance to be accessed later.
NOTE: since the background migration thread and return path thread run
completely concurrently, it doesn't always mean the hint will be applied
every single time. For example, it's possible that the return path thread
receives multiple page requests in a row without the background thread
getting the chance to consume one. In such case, the preempt thread only
provide the hint if the previous hint has been consumed. After all,
there's no point queuing hints when we only have one linear scanner.
This could measureably improve the simple sequential memory access pattern
during postcopy (when preempt is on). For random accesses, I can measure a
slight increase of remote page fault latency from ~500us -> ~600us, that
could be a trade-off to have such hint mechanism, and after all that's
still greatly improved comparing to vanilla postcopy on random (~10ms).
The patch is verified by our QE team in a video streaming test case, to
reduce the pause of the video from ~1min to a few seconds when switching
over to postcopy with preempt mode.
Reported-by: Xiaohui Li <xiaohli@redhat.com>
Tested-by: Xiaohui Li <xiaohli@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250424220705.195544-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Implement save_postcopy_prepare(), preparing for the enablement
of both multifd and postcopy.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Prasad Pandit <pjp@fedoraproject.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Message-ID: <20250411114534.3370816-5-ppandit@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
control_save_page() is for RDMA only, unfold it to make the code more
clear.
In addition:
- Similar to other branches style in ram_save_target_page(), involve RDMA
only if the condition 'migrate_rdma()' is true.
- Further simplify the code by removing the RAM_SAVE_CONTROL_NOT_SUPP.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Message-ID: <20250305062825.772629-6-lizhijian@fujitsu.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
A few functions now end with a label. The next commit will clean them
up.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20250407082643.2310002-3-armbru@redhat.com>
[Straightforward conflict with commit 988ad4cceb (hw/loongarch/virt:
Fix cpuslot::cpu set at last in virt_cpu_plug()) resolved]
Convert the existing includes with sed.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Address an error in RDMA-based migration by ensuring RDMA is prioritized
when saving pages in `ram_save_target_page()`.
Previously, the RDMA protocol's page-saving step was placed after other
protocols due to a refactoring in commit bc38dc2f5f. This led to migration
failures characterized by unknown control messages and state loading errors
destination:
(qemu) qemu-system-x86_64: Unknown control message QEMU FILE
qemu-system-x86_64: error while loading state section id 1(ram)
qemu-system-x86_64: load of migration failed: Operation not permitted
source:
(qemu) qemu-system-x86_64: RDMA is in an error state waiting migration to abort!
qemu-system-x86_64: failed to save SaveStateEntry with id(name): 1(ram): -1
qemu-system-x86_64: rdma migration: recv polling control error!
qemu-system-x86_64: warning: Early error. Sending error.
qemu-system-x86_64: warning: rdma migration: send polling control error
RDMA migration implemented its own protocol/method to send pages to
destination side, hand over to RDMA first to prevent pages being saved by
other protocol.
Fixes: bc38dc2f5f ("migration: refactor ram_save_target_page functions")
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Message-ID: <20250305062825.772629-2-lizhijian@fujitsu.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
There's no point passing the error into migration cancel only for it
to call migrate_set_error().
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-ID: <20250213175927.19642-2-farosas@suse.de>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Refactor ram_save_target_page legacy and multifd
functions into one. Other than simplifying it,
it frees 'migration_ops' object from usage, so it
is expunged.
Signed-off-by: Prasad Pandit <pjp@fedoraproject.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Message-ID: <20250127120823.144949-3-ppandit@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add the cpr-transfer migration mode, which allows the user to transfer
a guest to a new QEMU instance on the same host with minimal guest pause
time, by preserving guest RAM in place, albeit with new virtual addresses
in new QEMU, and by preserving device file descriptors. Pages that were
locked in memory for DMA in old QEMU remain locked in new QEMU, because the
descriptor of the device that locked them remains open.
cpr-transfer preserves memory and devices descriptors by sending them to
new QEMU over a unix domain socket using SCM_RIGHTS. Such CPR state cannot
be sent over the normal migration channel, because devices and backends
are created prior to reading the channel, so this mode sends CPR state
over a second "cpr" migration channel. New QEMU reads the cpr channel
prior to creating devices or backends. The user specifies the cpr channel
in the channel arguments on the outgoing side, and in a second -incoming
command-line parameter on the incoming side.
The user must start old QEMU with the the '-machine aux-ram-share=on' option,
which allows anonymous memory to be transferred in place to the new process
by transferring a memory descriptor for each ram block. Memory-backend
objects must have the share=on attribute, but memory-backend-epc is not
supported.
The user starts new QEMU on the same host as old QEMU, with command-line
arguments to create the same machine, plus the -incoming option for the
main migration channel, like normal live migration. In addition, the user
adds a second -incoming option with channel type "cpr". This CPR channel
must support file descriptor transfer with SCM_RIGHTS, i.e. it must be a
UNIX domain socket.
To initiate CPR, the user issues a migrate command to old QEMU, adding
a second migration channel of type "cpr" in the channels argument.
Old QEMU stops the VM, saves state to the migration channels, and enters
the postmigrate state. New QEMU mmap's memory descriptors, and execution
resumes.
The implementation splits qmp_migrate into start and finish functions.
Start sends CPR state to new QEMU, which responds by closing the CPR
channel. Old QEMU detects the HUP then calls finish, which connects the
main migration channel.
In summary, the usage is:
qemu-system-$arch -machine aux-ram-share=on ...
start new QEMU with "-incoming <main-uri> -incoming <cpr-channel>"
Issue commands to old QEMU:
migrate_set_parameter mode cpr-transfer
{"execute": "migrate", ...
{"channel-type": "main"...}, {"channel-type": "cpr"...} ... }
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-17-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
It's not straightforward to see why src QEMU needs to sync multifd during
setup() phase. After all, there's no page queued at that point.
For old QEMUs, there's a solid reason: EOS requires it to work. While it's
clueless on the new QEMUs which do not take EOS message as sync requests.
One will figure that out only when this is conditionally removed. In fact,
the author did try it out. Logically we could still avoid doing this on
new machine types, however that needs a separate compat field and that can
be an overkill in some trivial overhead in setup() phase.
Let's instead document it completely, to avoid someone else tries this
again and do the debug one more time, or anyone confused on why this ever
existed.
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Message-Id: <20241206224755.1108686-8-peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The src flush condition check is over complicated, and it's getting more
out of control if postcopy will be involved.
In general, we have two modes to do the sync: legacy or modern ways.
Legacy uses per-section flush, modern uses per-round flush.
Mapped-ram always uses the modern, which is per-round.
Introduce two helpers, which can greatly simplify the code, and hopefully
make it readable again.
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Message-Id: <20241206224755.1108686-7-peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Multifd never worked with postcopy, at least yet so far.
Remove the sync processing there, because it's confusing, and they should
never appear. Now if RAM_SAVE_FLAG_MULTIFD_FLUSH is observed, we fail hard
instead of trying to invoke multifd code.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20241206224755.1108686-6-peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
RAM_SAVE_FLAG_MULTIFD_FLUSH message should always be correlated to a sync
request on src. Unify such message into one place, and conditionally send
the message only if necessary.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20241206224755.1108686-5-peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Firstly, we're going to use the multifd flag soon in multifd code, so ram.c
isn't gonna work.
Secondly, we have a separate RDMA flag dangling around, which is definitely
not obvious. There's one comment that helps, but not too much.
Put all RAM save flags altogether, so nothing will get overlooked.
Add a section explain why we can't use bits over 0x200.
Remove RAM_SAVE_FLAG_FULL as it's already not used in QEMU, as the comment
explained.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20241206224755.1108686-4-peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Commit 637280aeb2 ("migration/multifd: Avoid the final FLUSH in
complete()") stopped sending the RAM_SAVE_FLAG_MULTIFD_FLUSH flag at
ram_save_complete(), because the sync on the destination side is not
needed due to the last iteration of find_dirty_block() having already
done it.
However, that commit overlooked that multifd_ram_flush_and_sync() on the
source side is also not needed at ram_save_complete(), for the same
reason.
Moreover, removing the RAM_SAVE_FLAG_MULTIFD_FLUSH but keeping the
multifd_ram_flush_and_sync() means that currently the recv threads will
hang when receiving the MULTIFD_FLAG_SYNC message, waiting for the
destination sync which only happens when RAM_SAVE_FLAG_MULTIFD_FLUSH is
received.
Luckily, multifd is still all working fine because recv side cleanup
code (mostly multifd_recv_sync_main()) is smart enough to make sure even
if recv threads are stuck at SYNC it'll get kicked out. And since this
is the completion phase of migration, nothing else will be sent after
the SYNCs.
This needs to be fixed because in the future VFIO will have data to push
after ram_save_complete() and we don't want the recv thread to be stuck
in the MULTIFD_FLAG_SYNC message.
Remove the unnecessary (and buggy) invocation of
multifd_ram_flush_and_sync().
For very old binaries (multifd_flush_after_each_section==true), the
flush_and_sync is still needed because each EOS received on destination
will enforce all-channel sync once.
Stable branches do not need this patch, as no real bug I can think of
that will go wrong there.. so not attaching Fixes to be clear on the
backport not needed.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20241206224755.1108686-2-peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Headers in include/sysemu/ are not only related to system
*emulation*, they are also used by virtualization. Rename
as system/ which is clearer.
Files renamed manually then mechanical change using sed tool.
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Lei Yang <leiyang@redhat.com>
Message-Id: <20241203172445.28576-1-philmd@linaro.org>
Now with the current migration_is_running(), it will report exactly the
opposite of what will be reported by migration_is_idle().
Drop migration_is_idle(), instead use "!migration_is_running()" which
should be identical on functionality.
In reality, most of the idle check is inverted, so it's even easier to
write with "migrate_is_running()" check.
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20241024213056.1395400-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
This helper is mostly the same as migration_is_running(), except that one
has COLO reported as true, the other has CANCELLING reported as true.
Per my past years experience on the state changes, none of them should
matter.
To make it slightly safer, report both COLO || CANCELLING to be true in
migration_is_running(), then drop the other one. We kept the 1st only
because the name is simpler, and clear enough.
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20241024213056.1395400-5-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
When VM is configured with huge memory, the current throttle logic
doesn't look like to scale, because migration_trigger_throttle()
is only called for each iteration, so it won't be invoked for a long
time if one iteration can take a long time.
The periodic dirty sync aims to fix the above issue by synchronizing
the ramblock from remote dirty bitmap and, when necessary, triggering
the CPU throttle multiple times during a long iteration.
This is a trade-off between synchronization overhead and CPU throttle
impact.
Signed-off-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/f61f1b3653f2acf026901103e1c73d157d38b08f.1729146786.git.yong.huang@smartx.com
[peterx: make prev_cnt global, and reset for each migration]
Signed-off-by: Peter Xu <peterx@redhat.com>
The global static variable ram_state in fact is referred to by the
"rs" parameter in migration_bitmap_sync_precopy. For ease of calling
by the callees, use the global variable directly in
migration_bitmap_sync_precopy and remove "rs" parameter.
The migration_bitmap_sync_precopy will be exported in the next commit.
Signed-off-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/283c335d61463bf477160da91b24da45cdaf3e43.1729146786.git.yong.huang@smartx.com
Signed-off-by: Peter Xu <peterx@redhat.com>
../migration/ram.c:1873:23: error: ‘dirty’ may be used uninitialized [-Werror=maybe-uninitialized]
When 'block' != NULL, 'dirty' is initialized.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
This patch is part of a series that moves towards a consistent use of
g_assert_not_reached() rather than an ad hoc mix of different
assertion mechanisms.
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240919044641.386068-31-pierrick.bouvier@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This patch is part of a series that moves towards a consistent use of
g_assert_not_reached() rather than an ad hoc mix of different
assertion mechanisms.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240919044641.386068-5-pierrick.bouvier@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Separate the multifd sync from flushing the client data to the
channels. These two operations are closely related but not strictly
necessary to be executed together.
The multifd sync is intrinsic to how multifd works. The multiple
channels operate independently and may finish IO out of order in
relation to each other. This applies also between the source and
destination QEMU.
Flushing the data that is left in the client-owned data structures
(e.g. MultiFDPages_t) prior to sync is usually the right thing to do,
but that is particular to how the ram migration is implemented with
several passes over dirty data.
Make these two routines separate, allowing future code to call the
sync by itself if needed. This also allows the usage of
multifd_ram_send to be isolated to ram code.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Multifd currently has a simple scheduling mechanism that distributes
work to the various channels by keeping storage space within each
channel and an extra space that is given to the client. Each time the
client fills the space with data and calls into multifd, that space is
given to the next idle channel and a free storage space is taken from
the channel and given to client for the next iteration.
This means we always need (#multifd_channels + 1) memory slots to
operate multifd.
This is fine, except that the presence of this one extra memory slot
doesn't allow different types of payloads to be processed at the same
time in different channels, i.e. the data type of
multifd_send_state->pages needs to be the same as p->pages.
For each new data type different from MultiFDPage_t that is to be
handled, this logic would need to be duplicated by adding new fields
to multifd_send_state, to the channels and to multifd_send_pages().
Fix this situation by moving the extra slot into the client and using
only the generic type MultiFDSendData in the multifd core.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
We always do the flush when finishing one round of scan, and during
complete() phase we should scan one more round making sure no dirty page
existed. In that case we shouldn't need one explicit FLUSH at the end of
complete(), as when reaching there all pages should have been flushed.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Tested-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The 'compress' migration capability enables the old compression code
which has shown issues over the years and is thought to be less stable
and tested than the more recent multifd-based compression. The old
compression code has been deprecated in 8.2 and now is time to remove
it.
Deprecation commit 864128df46 ("migration: Deprecate old compression
method").
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The block migration has been considered obsolete since QEMU 8.2 in
favor of the more flexible storage migration provided by the
blockdev-mirror driver. Two releases have passed so now it's time to
remove it.
Deprecation commit 66db46ca83 ("migration: Deprecate block
migration").
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
migration/ram.c: API Conversion qemu_mutex_lock(),
and qemu_mutex_unlock() to WITH_QEMU_LOCK_GUARD macro
Signed-off-by: Will Gyda <vilhelmgyda@gmail.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Implemented recvbitmap tracking of received pages in multifd.
If the zero page appears for the first time in the recvbitmap, this
page is not checked and set.
If the zero page has already appeared in the recvbitmap, there is no
need to check the data but directly set the data to 0, because it is
unlikely that the zero page will be migrated multiple times.
Signed-off-by: Yuan Liu <yuan1.liu@intel.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240401154110.2028453-2-yuan1.liu@intel.com
[peterx: touch up the comment, as the bitmap is used outside postcopy now]
Signed-off-by: Peter Xu <peterx@redhat.com>
The .save_setup() handler has now an Error** argument that we can use
to propagate errors reported by the .log_global_start() handler. Do
that for the RAM. The caller qemu_savevm_state_setup() will store the
error under the migration stream for later detection in the migration
sequence.
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240320064911.545001-15-clg@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Since the return value (-ENOMEM) is not exploited, follow the
recommendations of qapi/error.h and change it to a bool
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240320064911.545001-14-clg@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Since the return value not exploited, follow the recommendations of
qapi/error.h and change it to a bool
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240320064911.545001-13-clg@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Now that the log_global*() handlers take an Error** parameter and
return a bool, do the same for memory_global_dirty_log_start() and
memory_global_dirty_log_stop(). The error is reported in the callers
for now and it will be propagated in the call stack in the next
changes.
To be noted a functional change in ram_init_bitmaps(), if the dirty
pages logger fails to start, there is no need to synchronize the dirty
pages bitmaps. colo_incoming_start_dirty_log() could be modified in a
similar way.
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Paul Durrant <paul@xen.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hyman Huang <yong.huang@smartx.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Acked-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240320064911.545001-12-clg@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
We will use it in ram_init_bitmaps() to clear the allocated bitmaps when
support for error reporting is added to memory_global_dirty_log_start().
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240320064911.545001-11-clg@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
This will be useful to report errors at a higher level, mostly in VFIO
today.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240320064911.545001-9-clg@redhat.com
[peterx: drop comment for ERRP_GUARD, per Markus]
Signed-off-by: Peter Xu <peterx@redhat.com>
The purpose is to record a potential error in the migration stream if
qemu_savevm_state_setup() fails. Most of the current .save_setup()
handlers can be modified to use the Error argument instead of managing
their own and calling locally error_report().
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Harsh Prateek Bora <harshpb@linux.ibm.com>
Cc: Halil Pasic <pasic@linux.ibm.com>
Cc: Thomas Huth <thuth@redhat.com>
Cc: Eric Blake <eblake@redhat.com>
Cc: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Cc: John Snow <jsnow@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240320064911.545001-8-clg@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
This will prepare ground for future changes adding an Error** argument
to the save_setup() handler. We need to make sure that on failure,
ram_save_setup() sets a new error.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240320064911.545001-5-clg@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
1. Add a dedicated handler for MigrationOps::ram_save_target_page in
multifd live migration.
2. Refactor ram_save_target_page_legacy so that the legacy and multifd
handlers don't have internal functions calling into each other.
Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Message-Id: <20240226195654.934709-4-hao.xiang@bytedance.com>
Link: https://lore.kernel.org/r/20240311180015.3359271-6-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>
1. Add zero_pages field in MultiFDPacket_t.
2. Implements the zero page detection and handling on the multifd
threads for non-compression, zlib and zstd compression backends.
3. Added a new value 'multifd' in ZeroPageDetection enumeration.
4. Adds zero page counters and updates multifd send/receive tracing
format to track the newly added counters.
Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240311180015.3359271-5-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>
This new parameter controls where the zero page checking is running.
1. If this parameter is set to 'legacy', zero page checking is
done in the migration main thread.
2. If this parameter is set to 'none', zero page checking is disabled.
Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Link: https://lore.kernel.org/r/20240311180015.3359271-4-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>
We currently only need to clear the mapped-ram file bitmap from the
migration thread during save_zero_page.
We're about to add support for zero page detection on the multifd
thread, so allow ramblock_set_file_bmap_atomic() to also clear the
bits.
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240311180015.3359271-3-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>
Delete the MigrationState parameter from migration_is_setup_or_active
and move it to the public API in misc.h.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Link: https://lore.kernel.org/r/1710179338-294359-3-git-send-email-steven.sistare@oracle.com
Signed-off-by: Peter Xu <peterx@redhat.com>
If a migration stream is broken, the address and flag reading can return
zero. Thus, an irrelevant flag error will be returned instead of EIO.
It can be fixed by additional check after the reading.
Signed-off-by: Maksim Davydov <davydov-max@yandex-team.ru>
Link: https://lore.kernel.org/r/20240304144203.158477-1-davydov-max@yandex-team.ru
Signed-off-by: Peter Xu <peterx@redhat.com>
- Bryan's fix on multifd compression level API
- Fabiano's mapped-ram series (base + multifd only)
- Steve's amend on cpr document in qapi/
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Merge tag 'migration-next-pull-request' of https://gitlab.com/peterx/qemu into staging
Migartion pull request for 20240304
- Bryan's fix on multifd compression level API
- Fabiano's mapped-ram series (base + multifd only)
- Steve's amend on cpr document in qapi/
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* tag 'migration-next-pull-request' of https://gitlab.com/peterx/qemu: (27 commits)
migration/multifd: Document two places for mapped-ram
tests/qtest/migration: Add a multifd + mapped-ram migration test
migration/multifd: Add mapped-ram support to fd: URI
migration/multifd: Support incoming mapped-ram stream format
migration/multifd: Support outgoing mapped-ram stream format
migration/multifd: Prepare multifd sync for mapped-ram migration
migration/multifd: Add incoming QIOChannelFile support
migration/multifd: Add outgoing QIOChannelFile support
migration/multifd: Add a wrapper for channels_created
migration/multifd: Allow receiving pages without packets
migration/multifd: Allow multifd without packets
migration/multifd: Decouple recv method from pages
migration/multifd: Rename MultiFDSend|RecvParams::data to compress_data
tests/qtest/migration: Add tests for mapped-ram file-based migration
migration/ram: Add incoming 'mapped-ram' migration
migration/ram: Add outgoing 'mapped-ram' migration
migration: Add mapped-ram URI compatibility check
migration/ram: Introduce 'mapped-ram' migration capability
migration/qemu-file: add utility methods for working with seekable channels
io: fsync before closing a file channel
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
# Conflicts:
# migration/ram.c
Add two documentations for mapped-ram migration on two spots that may not
be extremely clear.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240301091524.39900-1-peterx@redhat.com
Cc: Prasad Pandit <ppandit@redhat.com>
[peterx: fix two English errors per Prasad]
Signed-off-by: Peter Xu <peterx@redhat.com>
For the incoming mapped-ram migration we need to read the ramblock
headers, get the pages bitmap and send the host address of each
non-zero page to the multifd channel thread for writing.
Usage on HMP is:
(qemu) migrate_set_capability multifd on
(qemu) migrate_set_capability mapped-ram on
(qemu) migrate_incoming file:migfile
(the ram.h include needs to move because we've been previously relying
on it being included from migration.c. Now file.h will start including
multifd.h before migration.o is processed)
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-22-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
The new mapped-ram stream format uses a file transport and puts ram
pages in the migration file at their respective offsets and can be
done in parallel by using the pwritev system call which takes iovecs
and an offset.
Add support to enabling the new format along with multifd to make use
of the threading and page handling already in place.
This requires multifd to stop sending headers and leaving the stream
format to the mapped-ram code. When it comes time to write the data, we
need to call a version of qio_channel_write that can take an offset.
Usage on HMP is:
(qemu) stop
(qemu) migrate_set_capability multifd on
(qemu) migrate_set_capability mapped-ram on
(qemu) migrate_set_parameter max-bandwidth 0
(qemu) migrate_set_parameter multifd-channels 8
(qemu) migrate file:migfile
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-21-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
