[PATCH v1 3/3] migration: multifd: Enable zerocopy

[Leonardo Bras]

Call qio_channel_set_zerocopy(true) in the start of every multifd thread.

Change the send_write() interface of multifd, allowing it to pass down
flags for qio_channel_write*().

Pass down MSG_ZEROCOPY flag for sending memory pages, while keeping the
other data being sent at the default copying approach.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
---
 migration/multifd-zlib.c | 7 ++++---
 migration/multifd-zstd.c | 7 ++++---
 migration/multifd.c      | 9 ++++++---
 migration/multifd.h      | 3 ++-
 4 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/migration/multifd-zlib.c b/migration/multifd-zlib.c
index ab4ba75d75..d8cce1810a 100644
--- a/migration/multifd-zlib.c
+++ b/migration/multifd-zlib.c
@@ -160,12 +160,13 @@ static int zlib_send_prepare(MultiFDSendParams *p, 
uint32_t used, Error **errp)
  * @used: number of pages used
  * @errp: pointer to an error
  */
-static int zlib_send_write(MultiFDSendParams *p, uint32_t used, Error **errp)
+static int zlib_send_write(MultiFDSendParams *p, uint32_t used, int flags,
+                           Error **errp)
 {
     struct zlib_data *z = p->data;
 
-    return qio_channel_write_all(p->c, (void *)z->zbuff, p->next_packet_size,
-                                 errp);
+    return qio_channel_write_all_flags(p->c, (void *)z->zbuff,
+                                       p->next_packet_size, flags, errp);
 }
 
 /**
diff --git a/migration/multifd-zstd.c b/migration/multifd-zstd.c
index 693bddf8c9..fa063fd33e 100644
--- a/migration/multifd-zstd.c
+++ b/migration/multifd-zstd.c
@@ -171,12 +171,13 @@ static int zstd_send_prepare(MultiFDSendParams *p, 
uint32_t used, Error **errp)
  * @used: number of pages used
  * @errp: pointer to an error
  */
-static int zstd_send_write(MultiFDSendParams *p, uint32_t used, Error **errp)
+static int zstd_send_write(MultiFDSendParams *p, uint32_t used, int flags,
+                           Error **errp)
 {
     struct zstd_data *z = p->data;
 
-    return qio_channel_write_all(p->c, (void *)z->zbuff, p->next_packet_size,
-                                 errp);
+    return qio_channel_write_all_flags(p->c, (void *)z->zbuff,
+                                       p->next_packet_size, flags, errp);
 }
 
 /**
diff --git a/migration/multifd.c b/migration/multifd.c
index 377da78f5b..097621c12c 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -103,9 +103,10 @@ static int nocomp_send_prepare(MultiFDSendParams *p, 
uint32_t used,
  * @used: number of pages used
  * @errp: pointer to an error
  */
-static int nocomp_send_write(MultiFDSendParams *p, uint32_t used, Error **errp)
+static int nocomp_send_write(MultiFDSendParams *p, uint32_t used, int flags,
+                             Error **errp)
 {
-    return qio_channel_writev_all(p->c, p->pages->iov, used, errp);
+    return qio_channel_writev_all_flags(p->c, p->pages->iov, used, flags, 
errp);
 }
 
 /**
@@ -675,7 +676,8 @@ static void *multifd_send_thread(void *opaque)
             }
 
             if (used) {
-                ret = multifd_send_state->ops->send_write(p, used, &local_err);
+                ret = multifd_send_state->ops->send_write(p, used, 
MSG_ZEROCOPY,
+                                                          &local_err);
                 if (ret != 0) {
                     break;
                 }
@@ -815,6 +817,7 @@ static bool multifd_channel_connect(MultiFDSendParams *p,
         } else {
             /* update for tls qio channel */
             p->c = ioc;
+            qio_channel_set_zerocopy(ioc, true);
             qemu_thread_create(&p->thread, p->name, multifd_send_thread, p,
                                    QEMU_THREAD_JOINABLE);
        }
diff --git a/migration/multifd.h b/migration/multifd.h
index 8d6751f5ed..7243ba4185 100644
--- a/migration/multifd.h
+++ b/migration/multifd.h
@@ -157,7 +157,8 @@ typedef struct {
     /* Prepare the send packet */
     int (*send_prepare)(MultiFDSendParams *p, uint32_t used, Error **errp);
     /* Write the send packet */
-    int (*send_write)(MultiFDSendParams *p, uint32_t used, Error **errp);
+    int (*send_write)(MultiFDSendParams *p, uint32_t used, int flags,
+                      Error **errp);
     /* Setup for receiving side */
     int (*recv_setup)(MultiFDRecvParams *p, Error **errp);
     /* Cleanup for receiving side */
-- 
2.33.0