From 60d9222c8f50c3e5dd3df9ee84ddd1d1c4b35389 Mon Sep 17 00:00:00 2001 From: "Michael R. Hines" Date: Tue, 25 Jun 2013 21:35:36 -0400 Subject: [PATCH] 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 Reviewed-by: Paolo Bonzini Reviewed-by: Chegu Vinod Reviewed-by: Eric Blake Tested-by: Chegu Vinod Tested-by: Michael R. Hines Signed-off-by: Michael R. Hines Signed-off-by: Juan Quintela --- include/migration/migration.h | 2 ++ migration.c | 9 +++++++++ qapi-schema.json | 7 ++++++- 3 files changed, 17 insertions(+), 1 deletion(-) 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