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authorMichael R. Hines <mrhines@us.ibm.com>2013-06-25 21:35:36 -0400
committerJuan Quintela <quintela@redhat.com>2013-06-27 02:38:36 +0200
commit60d9222c8f50c3e5dd3df9ee84ddd1d1c4b35389 (patch)
treee15ec28f02b7d995171274aa47703244880dd827
parent43487c678d6e4e7182bfa70d2bc75422578782aa (diff)
downloadqemu-arm-60d9222c8f50c3e5dd3df9ee84ddd1d1c4b35389.tar.gz
rdma: introduce capability x-rdma-pin-all
This capability allows you to disable dynamic chunk registration for better throughput on high-performance links. For example, using an 8GB RAM virtual machine with all 8GB of memory in active use and the VM itself is completely idle using a 40 gbps infiniband link: 1. x-rdma-pin-all disabled total time: approximately 7.5 seconds @ 9.5 Gbps 2. x-rdma-pin-all enabled total time: approximately 4 seconds @ 26 Gbps These numbers would of course scale up to whatever size virtual machine you have to migrate using RDMA. Enabling this feature does *not* have any measurable affect on migration *downtime*. This is because, without this feature, all of the memory will have already been registered already in advance during the bulk round and does not need to be re-registered during the successive iteration rounds. Reviewed-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Chegu Vinod <chegu_vinod@hp.com> Reviewed-by: Eric Blake <eblake@redhat.com> Tested-by: Chegu Vinod <chegu_vinod@hp.com> Tested-by: Michael R. Hines <mrhines@us.ibm.com> Signed-off-by: Michael R. Hines <mrhines@us.ibm.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
-rw-r--r--include/migration/migration.h2
-rw-r--r--migration.c9
-rw-r--r--qapi-schema.json7
3 files changed, 17 insertions, 1 deletions
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 3ddd64ffcb..f0640e0eec 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -123,6 +123,8 @@ void migrate_add_blocker(Error *reason);
*/
void migrate_del_blocker(Error *reason);
+bool migrate_rdma_pin_all(void);
+
int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen,
uint8_t *dst, int dlen);
int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen);
diff --git a/migration.c b/migration.c
index 441a3b23f9..a704d48669 100644
--- a/migration.c
+++ b/migration.c
@@ -476,6 +476,15 @@ void qmp_migrate_set_downtime(double value, Error **errp)
max_downtime = (uint64_t)value;
}
+bool migrate_rdma_pin_all(void)
+{
+ MigrationState *s;
+
+ s = migrate_get_current();
+
+ return s->enabled_capabilities[MIGRATION_CAPABILITY_X_RDMA_PIN_ALL];
+}
+
int migrate_use_xbzrle(void)
{
MigrationState *s;
diff --git a/qapi-schema.json b/qapi-schema.json
index 78da5577af..a30a728dde 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -608,10 +608,15 @@
# This feature allows us to minimize migration traffic for certain work
# loads, by sending compressed difference of the pages
#
+# @x-rdma-pin-all: Controls whether or not the entire VM memory footprint is
+# mlock()'d on demand or all at once. Refer to docs/rdma.txt for usage.
+# Disabled by default. Experimental: may (or may not) be renamed after
+# further testing is complete. (since 1.6)
+#
# Since: 1.2
##
{ 'enum': 'MigrationCapability',
- 'data': ['xbzrle'] }
+ 'data': ['xbzrle', 'x-rdma-pin-all'] }
##
# @MigrationCapabilityStatus