| Message ID | 20200520123152.60527-8-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtio-mem: Paravirtualized memory hot(un)plug | expand |
* David Hildenbrand (david@redhat.com) wrote: > RDMA will pin all guest memory (as documented in docs/rdma.txt). We want > to disable RAM block discards - however, to keep it simple use > ram_block_discard_is_required() instead of inhibiting. > > Note: It is not sufficient to limit disabling to pin_all. Even when only > conditionally pinning 1 MB chunks, as soon as one page within such a > chunk was discarded and one page not, the discarded pages will be pinned > as well. > > Cc: "Michael S. Tsirkin" <mst@redhat.com> > Cc: Juan Quintela <quintela@redhat.com> > Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > migration/rdma.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/migration/rdma.c b/migration/rdma.c > index 967fda5b0c..57e2cbc8ca 100644 > --- a/migration/rdma.c > +++ b/migration/rdma.c > @@ -29,6 +29,7 @@ > #include "qemu/sockets.h" > #include "qemu/bitmap.h" > #include "qemu/coroutine.h" > +#include "exec/memory.h" > #include <sys/socket.h> > #include <netdb.h> > #include <arpa/inet.h> > @@ -4017,8 +4018,14 @@ void rdma_start_incoming_migration(const char *host_port, Error **errp) > Error *local_err = NULL; > > trace_rdma_start_incoming_migration(); > - rdma = qemu_rdma_data_init(host_port, &local_err); > > + /* Avoid ram_block_discard_disable(), cannot change during migration. */ > + if (ram_block_discard_is_required()) { > + error_setg(errp, "RDMA: cannot disable RAM discard"); > + return; > + } > + > + rdma = qemu_rdma_data_init(host_port, &local_err); > if (rdma == NULL) { > goto err; > } > @@ -4065,10 +4072,17 @@ void rdma_start_outgoing_migration(void *opaque, > const char *host_port, Error **errp) > { > MigrationState *s = opaque; > - RDMAContext *rdma = qemu_rdma_data_init(host_port, errp); > RDMAContext *rdma_return_path = NULL; > + RDMAContext *rdma; > int ret = 0; > > + /* Avoid ram_block_discard_disable(), cannot change during migration. */ > + if (ram_block_discard_is_required()) { > + error_setg(errp, "RDMA: cannot disable RAM discard"); > + return; > + } > + > + rdma = qemu_rdma_data_init(host_port, errp); > if (rdma == NULL) { > goto err; > } > -- > 2.25.4 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff --git a/migration/rdma.c b/migration/rdma.c index 967fda5b0c..57e2cbc8ca 100644 --- a/migration/rdma.c +++ b/migration/rdma.c @@ -29,6 +29,7 @@ #include "qemu/sockets.h" #include "qemu/bitmap.h" #include "qemu/coroutine.h" +#include "exec/memory.h" #include <sys/socket.h> #include <netdb.h> #include <arpa/inet.h> @@ -4017,8 +4018,14 @@ void rdma_start_incoming_migration(const char *host_port, Error **errp) Error *local_err = NULL; trace_rdma_start_incoming_migration(); - rdma = qemu_rdma_data_init(host_port, &local_err); + /* Avoid ram_block_discard_disable(), cannot change during migration. */ + if (ram_block_discard_is_required()) { + error_setg(errp, "RDMA: cannot disable RAM discard"); + return; + } + + rdma = qemu_rdma_data_init(host_port, &local_err); if (rdma == NULL) { goto err; } @@ -4065,10 +4072,17 @@ void rdma_start_outgoing_migration(void *opaque, const char *host_port, Error **errp) { MigrationState *s = opaque; - RDMAContext *rdma = qemu_rdma_data_init(host_port, errp); RDMAContext *rdma_return_path = NULL; + RDMAContext *rdma; int ret = 0; + /* Avoid ram_block_discard_disable(), cannot change during migration. */ + if (ram_block_discard_is_required()) { + error_setg(errp, "RDMA: cannot disable RAM discard"); + return; + } + + rdma = qemu_rdma_data_init(host_port, errp); if (rdma == NULL) { goto err; }
RDMA will pin all guest memory (as documented in docs/rdma.txt). We want to disable RAM block discards - however, to keep it simple use ram_block_discard_is_required() instead of inhibiting. Note: It is not sufficient to limit disabling to pin_all. Even when only conditionally pinning 1 MB chunks, as soon as one page within such a chunk was discarded and one page not, the discarded pages will be pinned as well. Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Juan Quintela <quintela@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- migration/rdma.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)