The patch add support L2 table cache for qcow2 disk. L2 table cache can improve IO read and write performance for qcow2 img. Example: random 4K read requests on a fully populated 100GB image (SSD backend and vm with directsync cacha mode), IOPS increased by 7 times. --- src/conf/domain_conf.c | 25 +++++++++++++++++++++++++ src/conf/domain_conf.h | 4 ++++ src/qemu/qemu_command.c | 7 +++++++ src/qemu/qemu_domain.c | 4 ++++ 4 files changed, 40 insertions(+) diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index b8b5345..cb9fb05 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -9502,6 +9502,8 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt, char *vendor = NULL; char *product = NULL; char *domain_name = NULL; + char *disk_l2_cache_size = NULL; + char *disk_cache_clean_interval = NULL; if (!(def = virDomainDiskDefNew(xmlopt))) return NULL; @@ -9701,6 +9703,27 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt, } } else if (virXMLNodeNameEqual(cur, "boot")) { /* boot is parsed as part of virDomainDeviceInfoParseXML */ + } else if (virXMLNodeNameEqual(cur, "diskCache")) { + disk_l2_cache_size = + virXMLPropString(cur, "disk_l2_cache_size"); + if (disk_l2_cache_size && + virStrToLong_ui(disk_l2_cache_size, NULL, 0, + &def->disk_cache.disk_l2_cache_size) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("invalid disk L2 cache size '%s'"), + disk_l2_cache_size); + goto error; + } + disk_cache_clean_interval = + virXMLPropString(cur, "disk_cache_clean_interval"); + if (disk_cache_clean_interval && + virStrToLong_ui(disk_cache_clean_interval, NULL, 0, + &def->disk_cache.disk_cache_clean_interval) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("invalid disk cache clean interval '%s'"), + disk_cache_clean_interval); + goto error; + } } } @@ -9903,6 +9926,8 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt, VIR_FREE(vendor); VIR_FREE(product); VIR_FREE(domain_name); + VIR_FREE(disk_l2_cache_size); + VIR_FREE(disk_cache_clean_interval); ctxt->node = save_ctxt; return def; diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index 71437dc..6396475 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -647,6 +647,10 @@ struct _virDomainDiskDef { unsigned int physical_block_size; } blockio; + struct { + unsigned int disk_l2_cache_size; + unsigned int disk_cache_clean_interval; + } disk_cache; virDomainBlockIoTuneInfo blkdeviotune; char *driverName; diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 4fc3176..4bc9412 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -1637,6 +1637,13 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk, if (qemuBuildDriveSourceStr(disk, qemuCaps, &opt) < 0) goto error; + + if (disk->disk_cache.disk_l2_cache_size > 0) + virBufferAsprintf(&opt, "l2-cache-size=%u,", + disk->disk_cache.disk_l2_cache_size); + if (disk->disk_cache.disk_cache_clean_interval > 0) + virBufferAsprintf(&opt, "cache-clean-interval=%u,", + disk->disk_cache.disk_cache_clean_interval); if (qemuDiskBusNeedsDeviceArg(disk->bus)) { char *drivealias = qemuAliasDiskDriveFromDisk(disk); diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index fee4481..4896bf7 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -8627,6 +8627,10 @@ qemuDomainDiskChangeSupported(virDomainDiskDefPtr disk, CHECK_EQ(ioeventfd, "ioeventfd", true); CHECK_EQ(event_idx, "event_idx", true); CHECK_EQ(copy_on_read, "copy_on_read", true); + CHECK_EQ(disk_cache.disk_l2_cache_size, + "diskCache disk_l2_cache_size", true); + CHECK_EQ(disk_cache.disk_cache_clean_interval, + "diskCache disk_cache_clean_interval", true); /* "snapshot" is a libvirt internal field and thus can be changed */ /* startupPolicy is allowed to be updated. Therefore not checked here. */ CHECK_EQ(transient, "transient", true); -- 1.8.3.1