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migration/multifd: Don't send ram data during SYNC

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Skip saving and loading any ram data in the packet in the case of a
SYNC. This fixes a shortcoming of the current code which requires a
reset of the MultiFDPages_t fields right after the previous
pending_job finishes, otherwise the very next job might be a SYNC and
multifd_send_fill_packet() will put the stale values in the packet.

By not calling multifd_ram_fill_packet(), we can stop resetting
MultiFDPages_t in the multifd core and leave that to the client code.

Actually moving the reset function is not yet done because
pages->num==0 is used by the client code to determine whether the
MultiFDPages_t needs to be flushed. The subsequent patches will
replace that with a generic flag that is not dependent on
MultiFDPages_t.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
This commit is contained in:
Fabiano Rosas 2024-08-27 14:45:58 -03:00
parent 87bb9e953e
commit d7e58f412c
1 changed files with 10 additions and 3 deletions
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13
migration/multifd.c
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@ -452,6 +452,7 @@ void multifd_send_fill_packet(MultiFDSendParams *p)
{
MultiFDPacket_t *packet = p->packet;
uint64_t packet_num;
bool sync_packet = p->flags & MULTIFD_FLAG_SYNC;
memset(packet, 0, p->packet_len);
@ -466,7 +467,9 @@ void multifd_send_fill_packet(MultiFDSendParams *p)
p->packets_sent++;
multifd_ram_fill_packet(p);
if (!sync_packet) {
multifd_ram_fill_packet(p);
}
trace_multifd_send_fill(p->id, packet_num,
p->flags, p->next_packet_size);
@ -574,7 +577,9 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp)
p->packet_num = be64_to_cpu(packet->packet_num);
p->packets_recved++;
ret = multifd_ram_unfill_packet(p, errp);
if (!(p->flags & MULTIFD_FLAG_SYNC)) {
ret = multifd_ram_unfill_packet(p, errp);
}
trace_multifd_recv_unfill(p->id, p->packet_num, p->flags,
p->next_packet_size);
@ -1536,7 +1541,9 @@ static void *multifd_recv_thread(void *opaque)
flags = p->flags;
/* recv methods don't know how to handle the SYNC flag */
p->flags &= ~MULTIFD_FLAG_SYNC;
has_data = p->normal_num || p->zero_num;
if (!(flags & MULTIFD_FLAG_SYNC)) {
has_data = p->normal_num || p->zero_num;
}
qemu_mutex_unlock(&p->mutex);
} else {
/*