Re: [libvirt] [PATCH v2 3/4] qemu: support metadata-cache-size for blockdev

Just set l2-cache-size to INT64_MAX for all format nodes of qcow2 type in block node graph. -drive configuration is not supported because we can not set l2 cache size down the backing chain in this case. Note that imlementation sets l2-cache-size and not cache-size.

Unfortunately at time of this patch setting cache-size to INT64_MAX fails and as guest performance depends only on l2 cache size and not refcount cache size (which is documented in recent qemu) we can set l2 directly.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy(a)virtuozzo.com&gt; --- src/qemu/qemu_block.c | 5 ++++- src/qemu/qemu_command.c | 23 +++++++++++++++++++++++ src/qemu/qemu_domain.c | 2 ++ src/util/virstoragefile.c | 1 + src/util/virstoragefile.h | 1 + 5 files changed, 31 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c index 5321dda..8771cc1 100644 --- a/src/qemu/qemu_block.c +++ b/src/qemu/qemu_block.c @@ -1322,7 +1322,6 @@ qemuBlockStorageSourceGetFormatQcow2Props(virStorageSourcePtr src, * 'pass-discard-snapshot' * 'pass-discard-other' * 'overlap-check' - * 'l2-cache-size' * 'l2-cache-entry-size' * 'refcount-cache-size' * 'cache-clean-interval' @@ -1331,6 +1330,10 @@ qemuBlockStorageSourceGetFormatQcow2Props(virStorageSourcePtr src, if (qemuBlockStorageSourceGetFormatQcowGenericProps(src, "qcow2", props) < 0) return -1;

+ if (src->metadata_cache_size == VIR_DOMAIN_DISK_METADATA_CACHE_SIZE_MAXIMUM &&> + virJSONValueObjectAdd(props, "I:l2-cache-size", INT64_MAX,

+ return -1; +> return 0; } diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index f59cbf5..12b2c8d 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -1330,6 +1330,20 @@ qemuCheckDiskConfig(virDomainDiskDefPtr disk, return -1; } + if (disk->metadata_cache_size) { + if (disk->src->format != VIR_STORAGE_FILE_QCOW2) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("metadata_cache_size can only be set for qcow2 disks")); + return -1; + } + + if (disk->metadata_cache_size != VIR_DOMAIN_DISK_METADATA_CACHE_SIZE_MAXIMUM) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("metadata_cache_size can only be set to 'maximum'")); + return -1; + } + } + if (qemuCaps) { if (disk->serial && disk->bus == VIR_DOMAIN_DISK_BUS_SCSI && @@ -1353,6 +1367,15 @@ qemuCheckDiskConfig(virDomainDiskDefPtr disk, _("detect_zeroes is not supported by this QEMU binary")); return -1; } + + if (disk->metadata_cache_size && + !(virQEMUCapsGet(qemuCaps, QEMU_CAPS_BLOCKDEV) && + virQEMUCapsGet(qemuCaps, QEMU_CAPS_QCOW2_L2_CACHE_SIZE))) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("setting metadata_cache_size is not supported by " + "this QEMU binary")); + return -1; + } } if (disk->serial && diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 045a7b4..23d9348 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -9074,6 +9074,7 @@ qemuDomainDiskChangeSupported(virDomainDiskDefPtr disk, /* "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); + CHECK_EQ(metadata_cache_size, "metadata_cache_size", true); /* Note: For some address types the address auto generation for * @disk has still not happened at this point (e.g. driver @@ -13244,6 +13245,7 @@ qemuDomainPrepareDiskSourceData(virDomainDiskDefPtr disk, src->iomode = disk->iomode; src->cachemode = disk->cachemode; src->discard = disk->discard; + src->metadata_cache_size = disk->metadata_cache_size; if (disk->device == VIR_DOMAIN_DISK_DEVICE_FLOPPY) src->floppyimg = true; diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c index 94c32d8..9089e2f 100644 --- a/src/util/virstoragefile.c +++ b/src/util/virstoragefile.c @@ -2210,6 +2210,7 @@ virStorageSourceCopy(const virStorageSource *src, ret->cachemode = src->cachemode; ret->discard = src->discard; ret->detect_zeroes = src->detect_zeroes; + ret->metadata_cache_size = src->metadata_cache_size; /* storage driver metadata are not copied */ ret->drv = NULL; diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h index 3ff6c4f..8b57399 100644 --- a/src/util/virstoragefile.h +++ b/src/util/virstoragefile.h @@ -331,6 +331,7 @@ struct _virStorageSource { int cachemode; /* enum virDomainDiskCache */ int discard; /* enum virDomainDiskDiscard */ int detect_zeroes; /* enum virDomainDiskDetectZeroes */ + int metadata_cache_size; /* enum virDomainDiskImageMetadataCacheSize */ bool floppyimg; /* set to true if the storage source is going to be used as a source for floppy drive */