Implement zero copy send on nocomp_send_write(), by making use of QIOChannel
writev + flags & flush interface.
Change multifd_send_sync_main() so flush_zero_copy() can be called
after each iteration in order to make sure all dirty pages are sent before
a new iteration is started. It will also flush at the beginning and at the
end of migration.
Also make it return -1 if flush_zero_copy() fails, in order to cancel
the migration process, and avoid resuming the guest in the target host
without receiving all current RAM.
This will work fine on RAM migration because the RAM pages are not usually freed,
and there is no problem on changing the pages content between writev_zero_copy() and
the actual sending of the buffer, because this change will dirty the page and
cause it to be re-sent on a next iteration anyway.
A lot of locked memory may be needed in order to use multifd migration
with zero-copy enabled, so disabling the feature should be necessary for
low-privileged users trying to perform multifd migrations.
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220513062836.965425-9-leobras@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Even though multifd_send_sync_main() currently emits error_reports, it's
callers don't really check it before continuing.
Change multifd_send_sync_main() to return -1 on error and 0 on success.
Also change all it's callers to make use of this change and possibly fail
earlier.
(This change is important to next patch on multifd zero copy
implementation, to make it sure an error in zero-copy flush does not go
unnoticed.
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220513062836.965425-7-leobras@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This variable, along with its helpers, is used to detect whether multiple
channel will be supported for migration. In follow up patches, there'll be
other capability that requires multi-channels. Hence move it outside multifd
specific code and make it public. Meanwhile rename it from "multifd" to
"multi_channels" to show its real meaning.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220331150857.74406-5-peterx@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
The hostname is cached N times, N equals to the multifd channels.
Drop that cache because after previous patch we've got s->hostname
being alive for the whole lifecycle of migration procedure.
Cc: Juan Quintela <quintela@redhat.com>
Cc: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220331150857.74406-3-peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
Rename num_normal_pages to total_normal_pages (peter)
We are only sending normal pages through multifd channels.
Later on this series, we are going to also send zero pages.
We are going to detect if a page is zero or non zero in the multifd
channel thread, not on the main thread.
So we receive an array of pages page->offset[N]
And we will end with:
p->normal[N - zero_pages]
p->zero[zero_pages].
In this patch, we just copy all the pages in offset to normal.
for (i = 0; i < pages->num; i++) {
p->narmal[p->normal_num] = pages->offset[i];
p->normal_num++:
}
Later in the series this becomes:
for (i = 0; i < pages->num; i++) {
if (buffer_is_zero(page->offset[i])) {
p->zerol[p->zero_num] = pages->offset[i];
p->zero_num++:
} else {
p->narmal[p->normal_num] = pages->offset[i];
p->normal_num++:
}
}
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
Improving comment (dave)
Renaming num_normal_pages to total_normal_pages (peter)
We will need to split it later in zero_num (number of zero pages) and
normal_num (number of normal pages). This name is better.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
To: <quintela@redhat.com>, <dgilbert@redhat.com>, <qemu-devel@nongnu.org>
CC: Li Zhijian <lizhijian@cn.fujitsu.com>
Date: Sat, 31 Jul 2021 22:05:51 +0800 (5 weeks, 4 days, 17 hours ago)
multifd with unsupported protocol will cause a segment fault.
(gdb) bt
#0 0x0000563b4a93faf8 in socket_connect (addr=0x0, errp=0x7f7f02675410) at ../util/qemu-sockets.c:1190
#1 0x0000563b4a797a03 in qio_channel_socket_connect_sync
(ioc=0x563b4d16e8c0, addr=0x0, errp=0x7f7f02675410) at
../io/channel-socket.c:145
#2 0x0000563b4a797abf in qio_channel_socket_connect_worker (task=0x563b4cd86c30, opaque=0x0) at ../io/channel-socket.c:168
#3 0x0000563b4a792631 in qio_task_thread_worker (opaque=0x563b4cd86c30) at ../io/task.c:124
#4 0x0000563b4a91da69 in qemu_thread_start (args=0x563b4c44bb80) at ../util/qemu-thread-posix.c:541
#5 0x00007f7fe9b5b3f9 in ?? ()
#6 0x0000000000000000 in ?? ()
It's enough to check migrate_multifd_is_allowed() in multifd cleanup() and
multifd setup() though there are so many other places using migrate_use_multifd().
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
To: qemu-devel <qemu-devel@nongnu.org>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Juan Quintela
<quintela@redhat.com>, Peter Xu <peterx@redhat.com>, Leonardo Bras Soares
Passos <lsoaresp@redhat.com>
Date: Wed, 1 Sep 2021 17:58:57 +0200 (1 week, 15 hours, 17 minutes ago)
[[PGP Signed Part:No public key for 35AB0B289C5DB258 created at 2021-09-01T17:58:57+0200 using RSA]]
When introducing yank functionality in the migration code I forgot
to cover the multifd send side.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Tested-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Since multifd creation is async with migration_channel_connect, we should
pass the hostname from MigrationState to MultiFDSendParams.
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Signed-off-by: Yan Jin <jinyan12@huawei.com>
Message-Id: <1600139042-104593-4-git-send-email-zhengchuan@huawei.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
It will be used later.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
No comp value needs to be zero.
