diff mbox series

[v1,3/4] migration: refactor ram_save_target_page functions

Message ID 20241126115748.118683-4-ppandit@redhat.com (mailing list archive)
State New
Headers show
Series Allow to enable multifd and postcopy migration together | expand

Commit Message

Prasad Pandit Nov. 26, 2024, 11:57 a.m. UTC
From: Prasad Pandit <pjp@fedoraproject.org>

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.

When both Multifd and Postcopy modes are enabled,
to avoid errors, the Multifd threads are active until
migration reaches the Postcopy mode. This is done by
checking the state returned by migration_in_postcopy().

Signed-off-by: Prasad Pandit <pjp@fedoraproject.org>
---
 migration/multifd-nocomp.c |  3 +-
 migration/ram.c            | 74 ++++++++++++--------------------------
 2 files changed, 24 insertions(+), 53 deletions(-)

v1: Further refactor ram_save_target_page() function to conflate
    save_zero_page() calls.

    Add migration_in_postcopy() call to check migration state
    instead of combining it with migrate_multifd().

v0: https://lore.kernel.org/qemu-devel/20241029150908.1136894-1-ppandit@redhat.com/T/#u
diff mbox series

Patch

diff --git a/migration/multifd-nocomp.c b/migration/multifd-nocomp.c
index 55191152f9..e92821e8f6 100644
--- a/migration/multifd-nocomp.c
+++ b/migration/multifd-nocomp.c
@@ -14,6 +14,7 @@ 
 #include "exec/ramblock.h"
 #include "exec/target_page.h"
 #include "file.h"
+#include "migration.h"
 #include "multifd.h"
 #include "options.h"
 #include "qapi/error.h"
@@ -345,7 +346,7 @@  retry:
 
 int multifd_ram_flush_and_sync(void)
 {
-    if (!migrate_multifd()) {
+    if (!migrate_multifd() || migration_in_postcopy()) {
         return 0;
     }
 
diff --git a/migration/ram.c b/migration/ram.c
index 05ff9eb328..9d1ec6209c 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -467,13 +467,6 @@  void ram_transferred_add(uint64_t bytes)
     }
 }
 
-struct MigrationOps {
-    int (*ram_save_target_page)(RAMState *rs, PageSearchStatus *pss);
-};
-typedef struct MigrationOps MigrationOps;
-
-MigrationOps *migration_ops;
-
 static int ram_save_host_page_urgent(PageSearchStatus *pss);
 
 /* NOTE: page is the PFN not real ram_addr_t. */
@@ -1323,9 +1316,9 @@  static int find_dirty_block(RAMState *rs, PageSearchStatus *pss)
         pss->page = 0;
         pss->block = QLIST_NEXT_RCU(pss->block, next);
         if (!pss->block) {
-            if (migrate_multifd() &&
-                (!migrate_multifd_flush_after_each_section() ||
-                 migrate_mapped_ram())) {
+            if (migrate_multifd() && !migration_in_postcopy()
+                && (!migrate_multifd_flush_after_each_section()
+                    || migrate_mapped_ram())) {
                 QEMUFile *f = rs->pss[RAM_CHANNEL_PRECOPY].pss_channel;
                 int ret = multifd_ram_flush_and_sync();
                 if (ret < 0) {
@@ -1986,55 +1979,39 @@  int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len,
 }
 
 /**
- * ram_save_target_page_legacy: save one target page
+ * ram_save_target_page: save one target page to the precopy thread
+ * OR to multifd workers.
  *
- * Returns the number of pages written
+ * Multifd mode: returns 1 if the page was queued, -1 otherwise.
+ * Non-multifd mode: returns the number of pages written.
  *
  * @rs: current RAM state
  * @pss: data about the page we want to send
  */
-static int ram_save_target_page_legacy(RAMState *rs, PageSearchStatus *pss)
+static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss)
 {
     ram_addr_t offset = ((ram_addr_t)pss->page) << TARGET_PAGE_BITS;
     int res;
 
+    if (!migrate_multifd()
+        || migrate_zero_page_detection() == ZERO_PAGE_DETECTION_LEGACY) {
+        if (save_zero_page(rs, pss, offset)) {
+            return 1;
+        }
+    }
+
+    if (migrate_multifd() && !migration_in_postcopy()) {
+        RAMBlock *block = pss->block;
+        return ram_save_multifd_page(block, offset);
+    }
+
     if (control_save_page(pss, offset, &res)) {
         return res;
     }
 
-    if (save_zero_page(rs, pss, offset)) {
-        return 1;
-    }
-
     return ram_save_page(rs, pss);
 }
 
-/**
- * ram_save_target_page_multifd: send one target page to multifd workers
- *
- * Returns 1 if the page was queued, -1 otherwise.
- *
- * @rs: current RAM state
- * @pss: data about the page we want to send
- */
-static int ram_save_target_page_multifd(RAMState *rs, PageSearchStatus *pss)
-{
-    RAMBlock *block = pss->block;
-    ram_addr_t offset = ((ram_addr_t)pss->page) << TARGET_PAGE_BITS;
-
-    /*
-     * While using multifd live migration, we still need to handle zero
-     * page checking on the migration main thread.
-     */
-    if (migrate_zero_page_detection() == ZERO_PAGE_DETECTION_LEGACY) {
-        if (save_zero_page(rs, pss, offset)) {
-            return 1;
-        }
-    }
-
-    return ram_save_multifd_page(block, offset);
-}
-
 /* Should be called before sending a host page */
 static void pss_host_page_prepare(PageSearchStatus *pss)
 {
@@ -2121,7 +2098,7 @@  static int ram_save_host_page_urgent(PageSearchStatus *pss)
 
         if (page_dirty) {
             /* Be strict to return code; it must be 1, or what else? */
-            if (migration_ops->ram_save_target_page(rs, pss) != 1) {
+            if (ram_save_target_page(rs, pss) != 1) {
                 error_report_once("%s: ram_save_target_page failed", __func__);
                 ret = -1;
                 goto out;
@@ -2190,7 +2167,7 @@  static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss)
             if (preempt_active) {
                 qemu_mutex_unlock(&rs->bitmap_mutex);
             }
-            tmppages = migration_ops->ram_save_target_page(rs, pss);
+            tmppages = ram_save_target_page(rs, pss);
             if (tmppages >= 0) {
                 pages += tmppages;
                 /*
@@ -2388,8 +2365,6 @@  static void ram_save_cleanup(void *opaque)
     xbzrle_cleanup();
     multifd_ram_save_cleanup();
     ram_state_cleanup(rsp);
-    g_free(migration_ops);
-    migration_ops = NULL;
 }
 
 static void ram_state_reset(RAMState *rs)
@@ -3055,13 +3030,8 @@  static int ram_save_setup(QEMUFile *f, void *opaque, Error **errp)
         return ret;
     }
 
-    migration_ops = g_malloc0(sizeof(MigrationOps));
-
     if (migrate_multifd()) {
         multifd_ram_save_setup();
-        migration_ops->ram_save_target_page = ram_save_target_page_multifd;
-    } else {
-        migration_ops->ram_save_target_page = ram_save_target_page_legacy;
     }
 
     bql_unlock();