[libvirt] [PATCH] Add support L2 table cache for qcow2 disk

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