[libvirt] [PATCH RFC 4/7] libxl: implement virDomainBlockStats
Joao Martins
joao.m.martins at oracle.com
Tue Sep 8 08:27:27 UTC 2015
Introduce initial support for domainBlockStats API call that
allow us to query block device statistics. openstack nova
uses this API call to query block statistics, alongside
virDomainMemoryStats and virDomainInterfaceStats. Note that
this patch only introduces it for VBD for starters. QDisk
will come in a separate patch series.
A new statistics data structure is introduced to fit common
statistics among others specific to the underlying block
backends. For the VBD statistics on linux these are exported
via sysfs on the path:
"/sys/bus/xen-backend/devices/vbd-<domid>-<devid>/statistics"
To calculate the block devid two libxl functions were ported
(libxlDiskPathMatches and libxlDiskPathParse) to libvirt to
make sure the devid is calculate in the same way as libxl.
Each backend implements its own function to extract statistics
and let there be handled the different platforms. An alternative
would be to reuse libvirt xen driver function.
VBD stats are exposed in reqs and number of sectors from
blkback, and it's up to us to convert it to sector sizes.
The sector size is gathered through xenstore in the device
backend entry "physical-sector-size". This adds up an extra
dependency namely of xenstore for doing the xs_read.
BlockStatsFlags variant is also implemented which has the
added benefit of getting the number of flush requests.
Signed-off-by: Joao Martins <joao.m.martins at oracle.com>
---
configure.ac | 2 +-
src/libxl/libxl_driver.c | 420 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 421 insertions(+), 1 deletion(-)
diff --git a/configure.ac b/configure.ac
index ef7fbdb..56fb266 100644
--- a/configure.ac
+++ b/configure.ac
@@ -896,7 +896,7 @@ if test "$with_libxl" != "no" ; then
LIBS="$LIBS $LIBXL_LIBS"
AC_CHECK_LIB([xenlight], [libxl_ctx_alloc], [
with_libxl=yes
- LIBXL_LIBS="$LIBXL_LIBS -lxenlight -lxenctrl"
+ LIBXL_LIBS="$LIBXL_LIBS -lxenlight -lxenctrl -lxenstore"
],[
if test "$with_libxl" = "yes"; then
fail=1
diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index dc83083..fd952a3 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -59,6 +59,7 @@
#include "network/bridge_driver.h"
#include "locking/domain_lock.h"
#include "virstats.h"
+#include <xenstore.h>
#define VIR_FROM_THIS VIR_FROM_LIBXL
@@ -75,6 +76,7 @@ VIR_LOG_INIT("libxl.libxl_driver");
#define LIBXL_CONFIG_FORMAT_SEXPR "xen-sxpr"
#define LIBXL_NB_TOTAL_CPU_STAT_PARAM 1
+#define LIBXL_NB_TOTAL_BLK_STAT_PARAM 6
#define HYPERVISOR_CAPABILITIES "/proc/xen/capabilities"
#define HYPERVISOR_XENSTORED "/dev/xen/xenstored"
@@ -103,6 +105,25 @@ struct _libxlOSEventHookInfo {
int id;
};
+/* Object used to store disk statistics across multiple xen backends */
+typedef struct _libxlBlockStats libxlBlockStats;
+typedef libxlBlockStats *libxlBlockStatsPtr;
+struct _libxlBlockStats {
+ long long rd_req;
+ long long rd_bytes;
+ long long wr_req;
+ long long wr_bytes;
+ long long f_req;
+
+ char *backend;
+ union {
+ struct {
+ long long ds_req;
+ long long oo_req;
+ } vbd;
+ } u;
+};
+
/* Function declarations */
static int
libxlDomainManagedSaveLoad(virDomainObjPtr vm,
@@ -4641,6 +4662,403 @@ libxlDomainIsUpdated(virDomainPtr dom)
}
static int
+libxlDiskPathMatches(const char *virtpath, const char *devtype,
+ int *index_r, int max_index,
+ int *partition_r, int max_partition)
+{
+ const char *p;
+ char *ep;
+ int tl, c;
+ long pl;
+
+ tl = strlen(devtype);
+ if (memcmp(virtpath, devtype, tl))
+ return 0;
+
+ /* We decode the drive letter as if it were in base 52
+ * with digits a-zA-Z, more or less */
+ *index_r = -1;
+ p = virtpath + tl;
+ for (;;) {
+ c = *p++;
+ if (c >= 'a' && c <= 'z') {
+ c -= 'a';
+ } else {
+ --p;
+ break;
+ }
+ (*index_r)++;
+ (*index_r) *= 26;
+ (*index_r) += c;
+
+ if (*index_r > max_index)
+ return 0;
+ }
+
+ if (!*p) {
+ *partition_r = 0;
+ return 1;
+ }
+
+ if (*p == '0')
+ return 0; /* leading zeroes not permitted in partition number */
+
+ if (virStrToLong_l(p, &ep, 10, &pl) < 0)
+ return 0;
+
+ if (pl > max_partition || *ep)
+ return 0;
+
+ *partition_r = pl;
+ return 1;
+}
+
+static int
+libxlDiskPathParse(const char *virtpath, int *pdisk, int *ppartition)
+{
+ int disk, partition;
+ char *ep;
+ unsigned long ul;
+ int chrused;
+
+ chrused = -1;
+ if ((sscanf(virtpath, "d%ip%i%n", &disk, &partition, &chrused) >= 2
+ && chrused == strlen(virtpath) && disk < (1<<20) && partition < 256)
+ ||
+ libxlDiskPathMatches(virtpath, "xvd",
+ &disk, (1<<20)-1,
+ &partition, 255)) {
+ if (pdisk) *pdisk = disk;
+ if (ppartition) *ppartition = partition;
+ if (disk <= 15 && partition <= 15)
+ return (202 << 8) | (disk << 4) | partition;
+ else
+ return (1 << 28) | (disk << 8) | partition;
+ }
+
+ errno = virStrToLong_ul(virtpath, &ep, 0, &ul);
+ if (!errno && !*ep && ul <= INT_MAX) {
+ /* FIXME: should parse ul to determine these. */
+ if (pdisk || ppartition)
+ return -1;
+ return ul;
+ }
+
+ if (libxlDiskPathMatches(virtpath, "hd",
+ &disk, 3,
+ &partition, 63)) {
+ if (pdisk) *pdisk = disk;
+ if (ppartition) *ppartition = partition;
+ return ((disk<2 ? 3 : 22) << 8) | ((disk & 1) << 6) | partition;
+ }
+ if (libxlDiskPathMatches(virtpath, "sd",
+ &disk, 15,
+ &partition, 15)) {
+ if (pdisk) *pdisk = disk;
+ if (ppartition) *ppartition = partition;
+ return (8 << 8) | (disk << 4) | partition;
+ }
+ return -1;
+}
+
+#define LIBXL_VBD_SECTOR_SIZE 512
+
+static int
+libxlDiskSectorSize(int domid, int devno)
+{
+ char *path, *val;
+ struct xs_handle *handle;
+ int ret = LIBXL_VBD_SECTOR_SIZE;
+ unsigned int len;
+
+ handle = xs_daemon_open_readonly();
+ if (!handle) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ "%s", _("cannot read sector size"));
+ return ret;
+ }
+
+ if (virAsprintf(&path, "/local/domain/%d/device/vbd/%d/backend",
+ domid, devno) < 0)
+ goto close;
+
+ if ((val = xs_read(handle, XBT_NULL, path, &len)) == NULL)
+ goto cleanup;
+
+ VIR_FREE(path);
+ if (virAsprintf(&path, "%s/physical-sector-size", val) < 0) {
+ VIR_FREE(val);
+ goto close;
+ }
+
+ VIR_FREE(val);
+ if ((val = xs_read(handle, XBT_NULL, path, &len)) == NULL)
+ goto cleanup;
+
+ if (sscanf(val, "%d", &ret) != 1)
+ ret = -1;
+
+ VIR_FREE(val);
+
+ cleanup:
+ VIR_FREE(path);
+ close:
+ xs_daemon_close(handle);
+ return ret;
+}
+
+static int
+libxlDomainBlockStatsVBD(virDomainObjPtr vm,
+ const char *dev,
+ libxlBlockStatsPtr stats)
+{
+ int ret = -1;
+ int devno = libxlDiskPathParse(dev, NULL, NULL);
+ int size = libxlDiskSectorSize(vm->def->id, devno);
+#ifdef __linux__
+ char *path, *name, *val;
+ unsigned long long stat;
+
+ if (VIR_STRDUP(stats->backend, "vbd") < 0) {
+ virReportError(VIR_ERR_OPERATION_INVALID,
+ "%s", _("cannot set backend"));
+ return -1;
+ }
+
+ ret = virAsprintf(&path, "/sys/bus/xen-backend/devices/vbd-%d-%d/statistics",
+ vm->def->id, devno);
+
+ if (!virFileExists(path)) {
+ virReportError(VIR_ERR_OPERATION_INVALID,
+ "%s", _("cannot open bus path"));
+ goto cleanup;
+ }
+
+#define LIBXL_SET_VBDSTAT(FIELD, VAR, MUL) \
+ if ((virAsprintf(&name, "%s/"FIELD, path) < 0) || \
+ (virFileReadAll(name, 256, &val) < 0) || \
+ (sscanf(val, "%llu", &stat) != 1)) { \
+ virReportError(VIR_ERR_OPERATION_INVALID, \
+ _("cannot read %s"), name); \
+ goto cleanup; \
+ } \
+ VAR += (stat * MUL); \
+ VIR_FREE(name); \
+ VIR_FREE(val);
+
+ LIBXL_SET_VBDSTAT("f_req", stats->f_req, 1)
+ LIBXL_SET_VBDSTAT("wr_req", stats->wr_req, 1)
+ LIBXL_SET_VBDSTAT("rd_req", stats->rd_req, 1)
+ LIBXL_SET_VBDSTAT("wr_sect", stats->wr_bytes, size)
+ LIBXL_SET_VBDSTAT("rd_sect", stats->rd_bytes, size)
+
+ LIBXL_SET_VBDSTAT("ds_req", stats->u.vbd.ds_req, size)
+ LIBXL_SET_VBDSTAT("oo_req", stats->u.vbd.oo_req, 1)
+ ret = 0;
+
+ cleanup:
+ VIR_FREE(name);
+ VIR_FREE(path);
+ VIR_FREE(val);
+
+#undef LIBXL_SET_VBDSTAT
+
+#else
+ virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
+ "%s", _("platform unsupported"));
+#endif
+ return ret;
+}
+
+static int
+libxlDomainBlockStatsGatherSingle(virDomainObjPtr vm,
+ const char *path,
+ libxlBlockStatsPtr stats)
+{
+ virDomainDiskDefPtr disk;
+ const char *disk_drv;
+ int ret = -1, disk_fmt;
+
+ if (!(disk = virDomainDiskByName(vm->def, path, false))) {
+ virReportError(VIR_ERR_OPERATION_INVALID,
+ _("invalid path: %s"), path);
+ return ret;
+ }
+
+ disk_fmt = virDomainDiskGetFormat(disk);
+ if (!(disk_drv = virDomainDiskGetDriver(disk)))
+ disk_drv = "qemu";
+
+ if (STREQ(disk_drv, "phy")) {
+ if (disk_fmt != VIR_STORAGE_FILE_RAW &&
+ disk_fmt != VIR_STORAGE_FILE_NONE) {
+ virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
+ _("unsupported format %s"),
+ virStorageFileFormatTypeToString(disk_fmt));
+ return ret;
+ }
+
+ ret = libxlDomainBlockStatsVBD(vm, path, stats);
+ } else {
+ virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
+ _("unsupported disk driver %s"),
+ disk_drv);
+ return ret;
+ }
+ return ret;
+}
+
+static int
+libxlDomainBlockStatsGather(virDomainObjPtr vm,
+ const char *path,
+ libxlBlockStatsPtr stats)
+{
+ int ret = -1;
+ if (*path) {
+ if (libxlDomainBlockStatsGatherSingle(vm, path, stats) < 0)
+ return ret;
+ } else {
+ size_t i;
+ for (i = 0; i < vm->def->ndisks; ++i) {
+ if (libxlDomainBlockStatsGatherSingle(vm, vm->def->disks[i]->dst,
+ stats) < 0)
+ return ret;
+ }
+ }
+ return 0;
+}
+
+static int
+libxlDomainBlockStats(virDomainPtr dom,
+ const char *path,
+ virDomainBlockStatsPtr stats)
+{
+ libxlDriverPrivatePtr driver = dom->conn->privateData;
+ virDomainObjPtr vm;
+ libxlBlockStats blkstats;
+ int ret = -1;
+
+ if (!(vm = libxlDomObjFromDomain(dom)))
+ goto cleanup;
+
+ if (virDomainBlockStatsEnsureACL(dom->conn, vm->def) < 0)
+ goto cleanup;
+
+ if (libxlDomainObjBeginJob(driver, vm, LIBXL_JOB_QUERY) < 0)
+ goto cleanup;
+
+ if (!virDomainObjIsActive(vm)) {
+ virReportError(VIR_ERR_OPERATION_INVALID,
+ "%s", _("domain is not running"));
+ goto endjob;
+ }
+
+ memset(&blkstats, 0, sizeof(libxlBlockStats));
+ if ((ret = libxlDomainBlockStatsGather(vm, path, &blkstats)) < 0)
+ goto endjob;
+
+ stats->rd_req = blkstats.rd_req;
+ stats->rd_bytes = blkstats.rd_bytes;
+ stats->wr_req = blkstats.wr_req;
+ stats->wr_bytes = blkstats.wr_bytes;
+ if (STREQ_NULLABLE(blkstats.backend, "vbd"))
+ stats->errs = blkstats.u.vbd.oo_req;
+ else
+ stats->errs = -1;
+
+ endjob:
+ if (!libxlDomainObjEndJob(driver, vm)) {
+ virObjectUnlock(vm);
+ vm = NULL;
+ }
+
+ cleanup:
+ if (vm)
+ virObjectUnlock(vm);
+ return ret;
+}
+
+static int
+libxlDomainBlockStatsFlags(virDomainPtr dom,
+ const char *path,
+ virTypedParameterPtr params,
+ int *nparams,
+ unsigned int flags)
+{
+ libxlDriverPrivatePtr driver = dom->conn->privateData;
+ virDomainObjPtr vm;
+ libxlBlockStats blkstats;
+ int nstats;
+ int ret = -1;
+
+ virCheckFlags(VIR_TYPED_PARAM_STRING_OKAY, -1);
+
+ flags &= ~VIR_TYPED_PARAM_STRING_OKAY;
+
+ if (!(vm = libxlDomObjFromDomain(dom)))
+ goto cleanup;
+
+ if (virDomainBlockStatsFlagsEnsureACL(dom->conn, vm->def) < 0)
+ goto cleanup;
+
+ if (libxlDomainObjBeginJob(driver, vm, LIBXL_JOB_QUERY) < 0)
+ goto cleanup;
+
+ if (!virDomainObjIsActive(vm)) {
+ virReportError(VIR_ERR_OPERATION_INVALID,
+ "%s", _("domain is not running"));
+ goto endjob;
+ }
+
+ /* return count of supported stats */
+ if (*nparams == 0) {
+ *nparams = LIBXL_NB_TOTAL_BLK_STAT_PARAM;
+ ret = 0;
+ goto endjob;
+ }
+
+ memset(&blkstats, 0, sizeof(libxlBlockStats));
+ if ((ret = libxlDomainBlockStatsGather(vm, path, &blkstats)) < 0)
+ goto endjob;
+
+ nstats = 0;
+
+#define LIBXL_BLKSTAT_ASSIGN_PARAM(VAR, NAME) \
+ if (nstats < *nparams && (blkstats.VAR) != -1) { \
+ if (virTypedParameterAssign(params + nstats, NAME, \
+ VIR_TYPED_PARAM_LLONG, (blkstats.VAR)) < 0) \
+ goto endjob; \
+ nstats++; \
+ }
+
+ LIBXL_BLKSTAT_ASSIGN_PARAM(wr_bytes, VIR_DOMAIN_BLOCK_STATS_WRITE_BYTES);
+ LIBXL_BLKSTAT_ASSIGN_PARAM(wr_req, VIR_DOMAIN_BLOCK_STATS_WRITE_REQ);
+
+ LIBXL_BLKSTAT_ASSIGN_PARAM(rd_bytes, VIR_DOMAIN_BLOCK_STATS_READ_BYTES);
+ LIBXL_BLKSTAT_ASSIGN_PARAM(rd_req, VIR_DOMAIN_BLOCK_STATS_READ_REQ);
+
+ LIBXL_BLKSTAT_ASSIGN_PARAM(f_req, VIR_DOMAIN_BLOCK_STATS_FLUSH_REQ);
+
+ if (STREQ_NULLABLE(blkstats.backend, "vbd"))
+ LIBXL_BLKSTAT_ASSIGN_PARAM(u.vbd.oo_req, VIR_DOMAIN_BLOCK_STATS_ERRS);
+
+ *nparams = nstats;
+
+#undef LIBXL_BLKSTAT_ASSIGN_PARAM
+
+ endjob:
+ if (!libxlDomainObjEndJob(driver, vm)) {
+ virObjectUnlock(vm);
+ vm = NULL;
+ }
+
+ cleanup:
+ if (vm)
+ virObjectUnlock(vm);
+ return ret;
+}
+
+static int
libxlDomainInterfaceStats(virDomainPtr dom,
const char *path,
virDomainInterfaceStatsPtr stats)
@@ -5459,6 +5877,8 @@ static virHypervisorDriver libxlHypervisorDriver = {
#endif
.nodeGetFreeMemory = libxlNodeGetFreeMemory, /* 0.9.0 */
.nodeGetCellsFreeMemory = libxlNodeGetCellsFreeMemory, /* 1.1.1 */
+ .domainBlockStats = libxlDomainBlockStats, /* 1.2.20 */
+ .domainBlockStatsFlags = libxlDomainBlockStatsFlags, /* 1.2.20 */
.domainInterfaceStats = libxlDomainInterfaceStats, /* 1.2.20 */
.domainMemoryStats = libxlDomainMemoryStats, /* 1.2.20 */
.domainGetCPUStats = libxlDomainGetCPUStats, /* 1.2.20 */
--
2.1.4
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