Random write IOPS will drop dramatically if qcow2 l2 cache could not cover the whole disk. This patch gives libvirt user a chance to adjust the qcow2 cache configuration. Three new qcow2 driver parameters are added. They are l2-cache-size, refcount-cache-size and cache-clean-interval. The following are from qcow2-cache.txt. The amount of virtual disk that can be mapped by the L2 and refcount caches (in bytes) is: disk_size = l2_cache_size * cluster_size / 8 disk_size = refcount_cache_size * cluster_size * 8 / refcount_bits The parameter "cache-clean-interval" defines an interval (in seconds). All cache entries that haven't been accessed during that interval are removed from memory. Signed-off-by: Liu Qing <liuqing(a)huayun.com&gt; --- Change since v3: a) copy qcow2 cache configurion from source to backing$ to backing file source.$ docs/formatdomain.html.in | 43 ++++++++++ docs/schemas/domaincommon.rng | 35 ++++++++ src/conf/domain_conf.c | 95 +++++++++++++++++++++- src/qemu/qemu_command.c | 6 ++ src/qemu/qemu_driver.c | 5 ++ src/util/virstoragefile.c | 3 + src/util/virstoragefile.h | 6 ++ .../qemuxml2argv-disk-drive-qcow2-cache.xml | 43 ++++++++++ .../qemuxml2xmlout-disk-drive-qcow2-cache.xml | 43 ++++++++++ tests/qemuxml2xmltest.c | 1 + 10 files changed, 279 insertions(+), 1 deletion(-) create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-drive-qcow2-cache.xml create mode 100644 tests/qemuxml2xmloutdata/qemuxml2xmlout-disk-drive-qcow2-cache.xml diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 8ca7637..245d5c4 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -3036,6 +3036,49 @@ set. (<span class="since">Since 3.5.0</span>) </li> </ul> + The <code>drive</code> element may contain a qcow2 sub element, which + allows to specifying further details related to qcow2 driver type. + <span class="since">Since 3.8.0</span> + <ul> + <li> + The optional <code>l2_cache_size</code> attribute controls how much + memory will be consumed by qcow2 l2 table cache in bytes. This + option is only valid when the driver type is qcow2. The default + size is 2097152. The amount of virtual disk that can be mapped by + the L2 caches (in bytes) is: + disk_size = l2_cache_size * cluster_size / 8 + <span class='since'>Since 3.8.0</span> + + <b>In general you should leave this option alone, unless you + are very certain you know what you are doing.</b> + </li> + <li> + The optional <code>refcount_cache_size</code> attribute controls + how much memory will be consumed by qcow2 reference count table + cache in bytes. This option is only valid when the driver type is + qcow2. The default size is 262144. The amount of virtual disk that + can be mapped by the refcount caches (in bytes) is: + disk_size = refcount_cache_size * cluster_size * 8 / refcount_bits + <span class='since'>Since 3.8.0</span> + + <b>In general you should leave this option alone, unless you + are very certain you know what you are doing.</b> + </li> + <li> + The optional <code>cache_clean_interval</code> attribute defines + an interval (in seconds). All cache entries that haven't been + accessed during that interval are removed from memory. This option + is only valid when the driver type is qcow2. The default + value is 0, which disables this feature. If the interval is too + short, it will cause frequent cache write back and load, which + impact performance. If the interval is too long, unused cache + will still consume memory until it's been written back to disk. + <span class='since'>Since 3.8.0</span> + + <b>In general you should leave this option alone, unless you + are very certain you know what you are doing.</b> + </li> + </ul> </dd> <dt><code>backenddomain</code></dt> <dd>The optional <code>backenddomain</code> element allows specifying a diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index c9a4f7a..e4200fe 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -1756,6 +1756,23 @@ </element> </define> <!-- + Parameters for qcow2 driver + --> + <define name="qcow2Driver"> + <element name="qcow2"> + <optional> + <ref name="qcow2_l2_cache_size"/> + </optional> + <optional> + <ref name="qcow2_refcount_cache_size"/> + </optional> + <optional> + <ref name="qcow2_cache_clean_interval"/> + </optional> + </element> + </define> + + <!-- Disk may use a special driver for access. --> <define name="diskDriver"> @@ -1794,6 +1811,9 @@ <ref name="detect_zeroes"/> </optional> <ref name="virtioOptions"/> + <zeroOrMore> + <ref name="qcow2Driver"/> + </zeroOrMore> <empty/> </element> </define> @@ -1889,6 +1909,21 @@ </choice> </attribute> </define> + <define name="qcow2_l2_cache_size"> + <attribute name='l2_cache_size'> + <ref name="unsignedInt"/> + </attribute> + </define> + <define name="qcow2_refcount_cache_size"> + <attribute name='refcount_cache_size'> + <ref name="unsignedInt"/> + </attribute> + </define> + <define name="qcow2_cache_clean_interval"> + <attribute name='cache_clean_interval'> + <ref name="unsignedInt"/> + </attribute> + </define> <define name="controller"> <element name="controller"> <optional> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index a43b25c..4949e8b 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -5734,6 +5734,28 @@ virDomainDeviceLoadparmIsValid(const char *loadparm) static void +virDoaminQcow2CacheOptionsFormat(virBufferPtr buf, + virDomainDiskDefPtr def) +{ + virBuffer qcow2Buff = VIR_BUFFER_INITIALIZER; + if (def->src->l2_cache_size > 0) + virBufferAsprintf(&qcow2Buff, " l2_cache_size='%llu'", + def->src->l2_cache_size); + if (def->src->refcount_cache_size > 0) + virBufferAsprintf(&qcow2Buff, " refcount_cache_size='%llu'", + def->src->refcount_cache_size); + if (def->src->cache_clean_interval > 0) + virBufferAsprintf(&qcow2Buff, " cache_clean_interval='%llu'", + def->src->cache_clean_interval); + + if (virBufferUse(&qcow2Buff)) { + virBufferAddLit(buf, "<qcow2"); + virBufferAddBuffer(buf, &qcow2Buff); + virBufferAddLit(buf, "/>\n"); + } +} + +static void virDomainVirtioOptionsFormat(virBufferPtr buf, virDomainVirtioOptionsPtr virtio) { @@ -8572,15 +8594,69 @@ virDomainDiskDefParseValidate(const virDomainDiskDef *def) } } + if (def->src->format != VIR_STORAGE_FILE_QCOW2 && + (def->src->l2_cache_size > 0 || def->src->refcount_cache_size > 0 || + def->src->cache_clean_interval > 0)) { + virReportError(VIR_ERR_XML_ERROR, + _("Setting l2_cache_size, refcount_cache_size, " + "cache_clean_interval is not allowed for types " + "other than QCOW2")); + return -1; + } + return 0; } static int +virDomainDiskDefQcow2ParseXML(virDomainDiskDefPtr def, + xmlNodePtr cur) +{ + char *tmp = NULL; + int ret = -1; + + if ((tmp = virXMLPropString(cur, "l2_cache_size")) && + (virStrToLong_ullp(tmp, NULL, 10, &def->src->l2_cache_size) < 0)) { + virReportError(VIR_ERR_XML_ERROR, + _("Invalid l2_cache_size attribute in disk " + "driver element: %s"), tmp); + goto cleanup; + } + VIR_FREE(tmp); + + if ((tmp = virXMLPropString(cur, "refcount_cache_size")) && + (virStrToLong_ullp(tmp, NULL, 10, &def->src->refcount_cache_size) < 0)) { + virReportError(VIR_ERR_XML_ERROR, + _("Invalid refcount_cache_size attribute in disk " + "driver element: %s"), tmp); + goto cleanup; + } + VIR_FREE(tmp); + + if ((tmp = virXMLPropString(cur, "cache_clean_interval")) && + (virStrToLong_ullp(tmp, NULL, 10, &def->src->cache_clean_interval) < 0)) { + virReportError(VIR_ERR_XML_ERROR, + _("Invalid cache_clean_interval attribute in " + "disk driver element: %s"), tmp); + goto cleanup; + } + VIR_FREE(tmp); + + ret = 0; + + cleanup: + VIR_FREE(tmp); + + return ret; +} + + +static int virDomainDiskDefDriverParseXML(virDomainDiskDefPtr def, xmlNodePtr cur) { char *tmp = NULL; + xmlNodePtr child; int ret = -1; def->src->driverName = virXMLPropString(cur, "name"); @@ -8683,6 +8759,12 @@ virDomainDiskDefDriverParseXML(virDomainDiskDefPtr def, } VIR_FREE(tmp); + for (child = cur->children; child != NULL; child = child->next) { + if (virXMLNodeNameEqual(child, "qcow2") && + virDomainDiskDefQcow2ParseXML(def, child) < 0) { + goto cleanup; + } + } ret = 0; cleanup: @@ -21969,7 +22051,18 @@ virDomainDiskDefFormat(virBufferPtr buf, if (virBufferUse(&driverBuf)) { virBufferAddLit(buf, "<driver"); virBufferAddBuffer(buf, &driverBuf); - virBufferAddLit(buf, "/>\n"); + + if (def->src->l2_cache_size == 0 && + def->src->refcount_cache_size == 0 && + def->src->cache_clean_interval == 0) { + virBufferAddLit(buf, "/>\n"); + } else { + virBufferAddLit(buf, ">\n"); + virBufferAdjustIndent(buf, 2); + virDoaminQcow2CacheOptionsFormat(buf, def); + virBufferAdjustIndent(buf, -2); + virBufferAddLit(buf, "</driver>\n"); + } } if (def->src->auth) { diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index d553df5..ba81525 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -1433,6 +1433,12 @@ qemuBuildDriveSourceStr(virDomainDiskDefPtr disk, qemuformat = "luks"; virBufferAsprintf(buf, "format=%s,", qemuformat); } + if (disk->src->l2_cache_size > 0) + virBufferAsprintf(buf, "l2-cache-size=%llu,", disk->src->l2_cache_size); + if (disk->src->refcount_cache_size > 0) + virBufferAsprintf(buf, "refcount-cache-size=%llu,", disk->src->refcount_cache_size); + if (disk->src->cache_clean_interval > 0) + virBufferAsprintf(buf, "cache-clean-interval=%llu,", disk->src->cache_clean_interval); ret = 0; diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index e956839..c3b81e1 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -14318,6 +14318,11 @@ qemuDomainSnapshotDiskDataCollect(virQEMUDriverPtr driver, if (!(dd->src = virStorageSourceCopy(snap->def->disks[i].src, false))) goto error; + /* keep the qcow2 cache configuration */ + dd->src->l2_cache_size = vm->def->disks[i]->src->l2_cache_size; + dd->src->refcount_cache_size = vm->def->disks[i]->src->refcount_cache_size; + dd->src->cache_clean_interval = vm->def->disks[i]->src->cache_clean_interval; + if (virStorageSourceInitChainElement(dd->src, dd->disk->src, false) < 0) goto error; diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c index e94ad32..f23390f 100644 --- a/src/util/virstoragefile.c +++ b/src/util/virstoragefile.c @@ -2038,6 +2038,9 @@ virStorageSourceCopy(const virStorageSource *src, ret->physical = src->physical; ret->readonly = src->readonly; ret->shared = src->shared; + ret->l2_cache_size = src->l2_cache_size; + ret->refcount_cache_size = src->refcount_cache_size; + ret->cache_clean_interval = src->cache_clean_interval; /* storage driver metadata are not copied */ ret->drv = NULL; diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h index 6c388b1..9b5a5f3 100644 --- a/src/util/virstoragefile.h +++ b/src/util/virstoragefile.h @@ -280,6 +280,12 @@ struct _virStorageSource { /* metadata that allows identifying given storage source */ char *nodeformat; /* name of the format handler object */ char *nodestorage; /* name of the storage object */ + + unsigned long long l2_cache_size; /* qcow2 l2 cache size */ + /* qcow2 reference count table cache size */ + unsigned long long refcount_cache_size; + /* clean unused cache entries interval */ + unsigned long long cache_clean_interval; }; diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-qcow2-cache.xml b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-qcow2-cache.xml new file mode 100644 index 0000000..3f464db --- /dev/null +++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-qcow2-cache.xml @@ -0,0 +1,43 @@ +<domain type='qemu'> + <name>QEMUGuest1</name> + <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid> + <memory unit='KiB'>219136</memory> + <currentMemory unit='KiB'>219136</currentMemory> + <vcpu placement='static'>1</vcpu> + <os> + <type arch='i686' machine='pc'>hvm</type> + <boot dev='hd'/> + </os> + <clock offset='utc'/> + <on_poweroff>destroy</on_poweroff> + <on_reboot>restart</on_reboot> + <on_crash>destroy</on_crash> + <devices> + <emulator>/usr/bin/qemu-system-i686</emulator> + <disk type='block' device='disk'> + <driver name='qemu' type='qcow2' cache='none'> + <qcow2 l2_cache_size='2097152' refcount_cache_size='524288' cache_clean_interval='900'/> + </driver> + <source dev='/dev/HostVG/QEMUGuest1'/> + <target dev='hda' bus='ide'/> + <address type='drive' controller='0' bus='0' target='0' unit='0'/> + </disk> + <disk type='block' device='cdrom'> + <driver name='qemu' type='raw'/> + <source dev='/dev/HostVG/QEMUGuest2'/> + <target dev='hdc' bus='ide'/> + <readonly/> + <address type='drive' controller='0' bus='1' target='0' unit='0'/> + </disk> + <controller type='usb' index='0'> + <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/> + </controller> + <controller type='ide' index='0'> + <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> + </controller> + <controller type='pci' index='0' model='pci-root'/> + <input type='mouse' bus='ps2'/> + <input type='keyboard' bus='ps2'/> + <memballoon model='none'/> + </devices> +</domain> diff --git a/tests/qemuxml2xmloutdata/qemuxml2xmlout-disk-drive-qcow2-cache.xml b/tests/qemuxml2xmloutdata/qemuxml2xmlout-disk-drive-qcow2-cache.xml new file mode 100644 index 0000000..3f464db --- /dev/null +++ b/tests/qemuxml2xmloutdata/qemuxml2xmlout-disk-drive-qcow2-cache.xml @@ -0,0 +1,43 @@ +<domain type='qemu'> + <name>QEMUGuest1</name> + <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid> + <memory unit='KiB'>219136</memory> + <currentMemory unit='KiB'>219136</currentMemory> + <vcpu placement='static'>1</vcpu> + <os> + <type arch='i686' machine='pc'>hvm</type> + <boot dev='hd'/> + </os> + <clock offset='utc'/> + <on_poweroff>destroy</on_poweroff> + <on_reboot>restart</on_reboot> + <on_crash>destroy</on_crash> + <devices> + <emulator>/usr/bin/qemu-system-i686</emulator> + <disk type='block' device='disk'> + <driver name='qemu' type='qcow2' cache='none'> + <qcow2 l2_cache_size='2097152' refcount_cache_size='524288' cache_clean_interval='900'/> + </driver> + <source dev='/dev/HostVG/QEMUGuest1'/> + <target dev='hda' bus='ide'/> + <address type='drive' controller='0' bus='0' target='0' unit='0'/> + </disk> + <disk type='block' device='cdrom'> + <driver name='qemu' type='raw'/> + <source dev='/dev/HostVG/QEMUGuest2'/> + <target dev='hdc' bus='ide'/> + <readonly/> + <address type='drive' controller='0' bus='1' target='0' unit='0'/> + </disk> + <controller type='usb' index='0'> + <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/> + </controller> + <controller type='ide' index='0'> + <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> + </controller> + <controller type='pci' index='0' model='pci-root'/> + <input type='mouse' bus='ps2'/> + <input type='keyboard' bus='ps2'/> + <memballoon model='none'/> + </devices> +</domain> diff --git a/tests/qemuxml2xmltest.c b/tests/qemuxml2xmltest.c index 0a87ced..fab1e19 100644 --- a/tests/qemuxml2xmltest.c +++ b/tests/qemuxml2xmltest.c @@ -461,6 +461,7 @@ mymain(void) DO_TEST("disk-drive-cache-v2-none", NONE); DO_TEST("disk-drive-cache-directsync", NONE); DO_TEST("disk-drive-cache-unsafe", NONE); + DO_TEST("disk-drive-qcow2-cache", NONE); DO_TEST("disk-drive-network-nbd", NONE); DO_TEST("disk-drive-network-nbd-export", NONE); DO_TEST("disk-drive-network-nbd-ipv6", NONE); -- 1.8.3.1

On 09/13/2017 05:21 AM, Liu Qing wrote: The difference you list doesn't make any sense. The only difference between this an V3 is removing the qemu_command.c from patch1. I did a git diff between the two trees I have from your patches: diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index c3b81e138..e95683965 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -14318,11 +14318,6 @@ qemuDomainSnapshotDiskDataCollect(virQEMUDriverPtr driver, if (!(dd->src = virStorageSourceCopy(snap->def->disks[i].src, false))) goto error; - /* keep the qcow2 cache configuration */ - dd->src->l2_cache_size = vm->def->disks[i]->src->l2_cache_size; - dd->src->refcount_cache_size = vm->def->disks[i]->src->refcount_cache_size; - dd->src->cache_clean_interval = vm->def->disks[i]->src->cache_clean_interval; - if (virStorageSourceInitChainElement(dd->src, dd->disk->src, false) < 0) goto error; I'll stick with the v3 version and adjustments from comments that I made. John