commit 4cbc9c7ffd95d2702cf7ffb3bfdf3f1f0ffdca07
author Li Qiang <liq3ea@gmail.com> Wed Aug 01 06:00:20 2018 -0700
committer Juan Quintela <quintela@redhat.com> Wed Aug 22 11:42:34 2018 +0200
tree c801c82f52bf803b7eae1fc360bc665ade81f26b
parent 3eb21fe9e5a06e485dbb27838422ef85f4ae7967

migrate/cpu-throttle: Add max-cpu-throttle migration parameter

Currently, the default maximum CPU throttle for migration is
99(CPU_THROTTLE_PCT_MAX). This is too big and can make a remarkable
performance effect for the guest. We see a lot of packets latency
exceed 500ms when the CPU_THROTTLE_PCT_MAX reached. This patch set
adds a new max-cpu-throttle parameter to limit the CPU throttle.

Signed-off-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

migration/migration.c

diff --git a/migration/migration.c b/migration/migration.c
index b7d9854..570da6c 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -71,6 +71,7 @@
 /* Define default autoconverge cpu throttle migration parameters */
 #define DEFAULT_MIGRATE_CPU_THROTTLE_INITIAL 20
 #define DEFAULT_MIGRATE_CPU_THROTTLE_INCREMENT 10
+#define DEFAULT_MIGRATE_MAX_CPU_THROTTLE 99
 
 /* Migration XBZRLE default cache size */
 #define DEFAULT_MIGRATE_XBZRLE_CACHE_SIZE (64 * 1024 * 1024)
@@ -697,6 +698,8 @@
     params->xbzrle_cache_size = s->parameters.xbzrle_cache_size;
     params->has_max_postcopy_bandwidth = true;
     params->max_postcopy_bandwidth = s->parameters.max_postcopy_bandwidth;
+    params->has_max_cpu_throttle = true;
+    params->max_cpu_throttle = s->parameters.max_cpu_throttle;
 
     return params;
 }
@@ -1043,6 +1046,15 @@
         return false;
     }
 
+    if (params->has_max_cpu_throttle &&
+        (params->max_cpu_throttle < params->cpu_throttle_initial ||
+         params->max_cpu_throttle > 99)) {
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
+                   "max_cpu_throttle",
+                   "an integer in the range of cpu_throttle_initial to 99");
+        return false;
+    }
+
     return true;
 }
 
@@ -1110,6 +1122,9 @@
     if (params->has_max_postcopy_bandwidth) {
         dest->max_postcopy_bandwidth = params->max_postcopy_bandwidth;
     }
+    if (params->has_max_cpu_throttle) {
+        dest->max_cpu_throttle = params->max_cpu_throttle;
+    }
 }
 
 static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
@@ -1185,6 +1200,9 @@
     if (params->has_max_postcopy_bandwidth) {
         s->parameters.max_postcopy_bandwidth = params->max_postcopy_bandwidth;
     }
+    if (params->has_max_cpu_throttle) {
+        s->parameters.max_cpu_throttle = params->max_cpu_throttle;
+    }
 }
 
 void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)
@@ -1962,7 +1980,6 @@
     return s->parameters.max_postcopy_bandwidth;
 }
 
-
 bool migrate_use_block(void)
 {
     MigrationState *s;
@@ -3160,6 +3177,9 @@
     DEFINE_PROP_SIZE("max-postcopy-bandwidth", MigrationState,
                       parameters.max_postcopy_bandwidth,
                       DEFAULT_MIGRATE_MAX_POSTCOPY_BANDWIDTH),
+    DEFINE_PROP_UINT8("max-cpu-throttle", MigrationState,
+                      parameters.max_cpu_throttle,
+                      DEFAULT_MIGRATE_MAX_CPU_THROTTLE),
 
     /* Migration capabilities */
     DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE),
@@ -3230,6 +3250,7 @@
     params->has_x_multifd_page_count = true;
     params->has_xbzrle_cache_size = true;
     params->has_max_postcopy_bandwidth = true;
+    params->has_max_cpu_throttle = true;
 
     qemu_sem_init(&ms->postcopy_pause_sem, 0);
     qemu_sem_init(&ms->postcopy_pause_rp_sem, 0);