On 07/25/2016 05:45 PM, Joao Martins wrote:
> Introduce initial support for domainBlockStats API call that
> allow us to query block device statistics. openstack nova
s/openstack/OpenStack/
> uses this API call to query block statistics, alongside
> virDomainMemoryStats and virDomainInterfaceStats. Note that
> this patch only introduces it for VBD for starters. QDisk
> would 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 devno libxlDiskPathToID is introduced.
> Each backend implements its own function to extract statistics
> and let there be handled the different platforms.
I reworded this to
Each backend implements its own function to extract statistics,
allowing support for multiple backends and different platforms.
>
> 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".
>
> 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@xxxxxxxxxx>
> ---
> Changes since v4:
> - No need to handle virtpath as devid - return id = -1 instead
> - Rework compilation of BlockStatsVBD compilation on other platforms.
> - Use disk->dst as opposed to plain path to also cover the case when
> input virtpath is path to file. Before it was returning "cannot find
> device number"
>
> Changes since v3:
> - No need for error in libxlDiskSectorSize()
> - Fix an identation issue.
> - Rework cleanup paths on libxlDiskSectorSize()
> - Do not unlock vm if libxlDomainObjEndJob() returns false and
> adjust to the newly introduced virDomainObjEndAPI()
> - Bump version to 2.1.0
>
> Changes since v1:
> - Fix identation issues
> - Set ret to LIBXL_VBD_SECTOR_SIZE
> - Reuse VIR_STRDUP error instead of doing virReportError
> when we fail to set stats->backend
> - Change virAsprintf(...) error checking
> - Change error to VIR_ERR_OPERATION_FAILED when xenstore path
> does not exist and when failing to read stat.
> - Resolve issues with 'make syntax-check' with cppi installed.
> - Remove libxlDiskPathMatches in favor of using virutil
> virDiskNameParse to fetch disk and partition index.
> - Rename libxlDiskPathParse to libxlDiskPathToID and rework
> function to just convert disk and partition index to devno.
> - Bump version to 1.2.22
> ---
> src/libxl/libxl_driver.c | 367 +++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 367 insertions(+)
>
> diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
> index f153f69..b33c898 100644
> --- a/src/libxl/libxl_driver.c
> +++ b/src/libxl/libxl_driver.c
> @@ -30,6 +30,7 @@
> #include <math.h>
> #include <libxl.h>
> #include <libxl_utils.h>
> +#include <xenstore.h>
> #include <fcntl.h>
> #include <regex.h>
>
> @@ -72,6 +73,7 @@ VIR_LOG_INIT("libxl.libxl_driver");
> #define LIBXL_DOM_REQ_HALT 4
>
> #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"
> @@ -100,6 +102,25 @@ 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,
> @@ -5031,6 +5052,350 @@ libxlDomainGetJobStats(virDomainPtr dom,
> }
>
> static int
> +libxlDiskPathToID(const char *virtpath)
> +{
> + static char const* drive_prefix[] = {"xvd", "hd", "sd"};
> + int disk, partition, chrused;
> + int fmt, id;
> + size_t i;
> +
> + fmt = id = -1;
> +
> + /* Find any disk prefixes we know about */
> + for (i = 0; i < ARRAY_CARDINALITY(drive_prefix); i++) {
> + if (STRPREFIX(virtpath, drive_prefix[i]) &&
> + !virDiskNameParse(virtpath, &disk, &partition)) {
> + fmt = i;
> + break;
> + }
> + }
> +
> + /* Handle it same way as xvd */
> + if (fmt < 0 &&
> + (sscanf(virtpath, "d%ip%i%n", &disk, &partition, &chrused) >= 2
> + && chrused == strlen(virtpath)))
> + fmt = 0;
> +
> + /* Test indexes ranges and calculate the device id */
> + switch (fmt) {
> + case 0: /* xvd */
> + if (disk <= 15 && partition <= 15)
> + id = (202 << 8) | (disk << 4) | partition;
> + else if ((disk <= ((1<<20)-1)) || partition <= 255)
> + id = (1 << 28) | (disk << 8) | partition;
> + break;
> + case 1: /* hd */
> + if (disk <= 3 && partition <= 63)
> + id = ((disk < 2 ? 3 : 22) << 8) | ((disk & 1) << 6) | partition;
> + break;
> + case 2: /* sd */
> + if (disk <= 15 && (partition <= 15))
> + id = (8 << 8) | (disk << 4) | partition;
> + break;
> + default: /* invalid */
> + break;
> + }
> + return id;
> +}
> +
> +#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) {
> + VIR_WARN("cannot read sector size");
> + return ret;
> + }
> +
> + path = val = NULL;
> + if (virAsprintf(&path, "/local/domain/%d/device/vbd/%d/backend",
> + domid, devno) < 0)
> + goto cleanup;
> +
> + if ((val = xs_read(handle, XBT_NULL, path, &len)) == NULL)
> + goto cleanup;
> +
> + VIR_FREE(path);
> + if (virAsprintf(&path, "%s/physical-sector-size", val) < 0)
> + goto cleanup;
> +
> + VIR_FREE(val);
> + if ((val = xs_read(handle, XBT_NULL, path, &len)) == NULL)
> + goto cleanup;
> +
> + if (sscanf(val, "%d", &ret) != 1)
> + ret = LIBXL_VBD_SECTOR_SIZE;
> +
> + cleanup:
> + VIR_FREE(val);
> + VIR_FREE(path);
> + xs_daemon_close(handle);
> + return ret;
> +}
> +
> +#ifdef __linux__
> +static int
> +libxlDomainBlockStatsVBD(virDomainObjPtr vm,
> + const char *dev,
> + libxlBlockStatsPtr stats)
> +{
> + int ret = -1;
> + int devno = libxlDiskPathToID(dev);
> + int size = libxlDiskSectorSize(vm->def->id, devno);
To avoid calling libxlDiskSectorSize() on an invalid devno, I moved it after the
devno validity check.
Looks good otherwise. ACK. I've pushed it with the tweaked commit message and
below diff squashed in.
Regards,
Jim
diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index b33c898..cb501cf 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -5148,7 +5148,7 @@ libxlDomainBlockStatsVBD(virDomainObjPtr vm,
{
int ret = -1;
int devno = libxlDiskPathToID(dev);
- int size = libxlDiskSectorSize(vm->def->id, devno);
+ int size;
char *path, *name, *val;
unsigned long long stat;
@@ -5158,6 +5158,9 @@ libxlDomainBlockStatsVBD(virDomainObjPtr vm,
"%s", _("cannot find device number"));
return ret;
}
+
+ size = libxlDiskSectorSize(vm->def->id, devno);
+
if (VIR_STRDUP(stats->backend, "vbd") < 0)
return ret;
--
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