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charset="utf-8" Put buffer can be async as long as the flush happens before the buffer will be recycled / reused. Do it for postcopy package data. Quick measurement shows a small VM the time to push / flush the package shrinks from 91us to 38us. Signed-off-by: Peter Xu Reviewed-by: Fabiano Rosas --- migration/savevm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/migration/savevm.c b/migration/savevm.c index 9d2109718a..d41e89228d 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1136,7 +1136,8 @@ int qemu_savevm_send_packaged(QEMUFile *f, const uint= 8_t *buf, size_t len) trace_qemu_savevm_send_packaged(); qemu_savevm_command_send(f, MIG_CMD_PACKAGED, 4, (uint8_t *)&tmp); =20 - qemu_put_buffer(f, buf, len); + /* We can use async put because the qemufile will be flushed right awa= y */ + qemu_put_buffer_async(f, buf, len, false); qemu_fflush(f); =20 return 0; --=20 2.50.1