[RFC][PATCH 1/2] libnvdimm: Introduce ND_CMD_GET_STAT to retrieve nvdimm statistics
Vaibhav Jain
vaibhav at linux.ibm.com
Mon Nov 9 08:15:48 AEDT 2020
Implement support for exposing generic nvdimm statistics via newly
introduced dimm-command ND_CMD_GET_STAT that can be handled by nvdimm
command handler function and provide values for these statistics back
to libnvdimm. Following generic nvdimm statistics are defined as an
enumeration in 'uapi/ndctl.h':
* "media_reads" : Number of media reads that have occurred since reboot.
* "media_writes" : Number of media writes that have occurred since reboot.
* "read_requests" : Number of read requests that have occurred since reboot.
* "write_requests" : Number of write requests that have occurred since reboot.
* "total_media_reads" : Total number of media reads that have occurred.
* "total_media_writes" : Total number of media writes that have occurred.
* "total_read_requests" : Total number of read requests that have occurred.
* "total_write_requests" : Total number of write requests that have occurred.
Apart from ND_CMD_GET_STAT ioctl these nvdimm statistics are also
exposed via sysfs '<nvdimm-device>/stats' directory for easy user-space
access like below:
/sys/class/nd/ndctl0/device/nmem0/stats # tail -n +1 *
==> media_reads <==
252197707602
==> media_writes <==
20684685172
==> read_requests <==
658810924962
==> write_requests <==
404464081574
In case a specific nvdimm-statistic is not supported than nvdimm
command handler function can simply return an error (e.g -ENOENT) for
request to read that nvdimm-statistic.
The value for a specific nvdimm-stat is exchanged via newly introduced
'struct nd_cmd_get_dimm_stat' that hold a single statistics and a
union of possible values types. Presently only '__s64' type of generic
attributes are supported. These attributes are defined in
'ndvimm/dimm_devs.c' via a helper macro 'NVDIMM_STAT_ATTR'.
Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
---
drivers/nvdimm/bus.c | 6 ++
drivers/nvdimm/dimm_devs.c | 109 +++++++++++++++++++++++++++++++++++++
drivers/nvdimm/nd.h | 5 ++
include/uapi/linux/ndctl.h | 27 +++++++++
4 files changed, 147 insertions(+)
diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 2304c6183822..d53564477437 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -794,6 +794,12 @@ static const struct nd_cmd_desc __nd_cmd_dimm_descs[] = {
.out_num = 1,
.out_sizes = { UINT_MAX, },
},
+ [ND_CMD_GET_STAT] = {
+ .in_num = 1,
+ .in_sizes = { sizeof(struct nd_cmd_get_dimm_stat), },
+ .out_num = 1,
+ .out_sizes = { sizeof(struct nd_cmd_get_dimm_stat), },
+ },
};
const struct nd_cmd_desc *nd_cmd_dimm_desc(int cmd)
diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index b59032e0859b..68aaa294def7 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -555,6 +555,114 @@ static umode_t nvdimm_firmware_visible(struct kobject *kobj, struct attribute *a
return a->mode;
}
+/* Request a dimm stat from the bus driver */
+static int __request_dimm_stat(struct nvdimm_bus *nvdimm_bus,
+ struct nvdimm *dimm, u64 stat_id,
+ s64 *stat_val)
+{
+ struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc;
+ struct nd_cmd_get_dimm_stat stat = { .stat_id = stat_id };
+ int rc, cmd_rc;
+
+ if (!test_bit(ND_CMD_GET_STAT, &dimm->cmd_mask)) {
+ pr_debug("CMD_GET_STAT not set for bus driver 0x%lx\n",
+ nd_desc->cmd_mask);
+ return -ENOENT;
+ }
+
+ /* Is stat requested is known & bus driver supports fetching stats */
+ if (stat_id <= ND_DIMM_STAT_INVALID || stat_id > ND_DIMM_STAT_MAX) {
+ WARN(1, "Unknown stat-id(%llu) requested", stat_id);
+ return -ENOENT;
+ }
+
+ /* Ask bus driver for its stat value */
+ rc = nd_desc->ndctl(nd_desc, dimm, ND_CMD_GET_STAT,
+ &stat, sizeof(stat), &cmd_rc);
+ if (rc || cmd_rc) {
+ pr_debug("Unable to request stat %lld. Error (%d,%d)\n",
+ stat_id, rc, cmd_rc);
+ return rc ? rc : cmd_rc;
+ }
+
+ /* Indicate error in case returned struct doesn't have the stat_id set */
+ if (stat.stat_id != stat_id) {
+ pr_debug("Invalid statid %llu returned\n", stat.stat_id);
+ return -ENOENT;
+ }
+
+ *stat_val = stat.int_val;
+ return 0;
+}
+
+static ssize_t nvdimm_stat_attr_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct nvdimm_stat_attr *nattr = container_of(attr, typeof(*nattr), attr);
+ struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
+ struct nvdimm *nvdimm = to_nvdimm(dev);
+ s64 stat_val;
+ int rc;
+
+ rc = __request_dimm_stat(nvdimm_bus, nvdimm, nattr->stat_id, &stat_val);
+
+ if (rc)
+ return rc;
+
+ return snprintf(buf, PAGE_SIZE, "%lld", stat_val);
+}
+
+static umode_t nvdimm_stats_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+ struct nvdimm_stat_attr *nattr = container_of(a, typeof(*nattr), attr.attr);
+ struct device *dev = container_of(kobj, typeof(*dev), kobj);
+ struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
+ struct nvdimm *nvdimm = to_nvdimm(dev);
+ u64 stat_val;
+ int rc;
+
+ /* request dimm stat from bus driver and is success mark attribute as visible */
+ rc = __request_dimm_stat(nvdimm_bus, nvdimm, nattr->stat_id, &stat_val);
+ if (rc)
+ pr_info("Unable to query stat %llu . Error(%d)\n", nattr->stat_id, rc);
+
+ return rc ? 0 : a->mode;
+}
+
+#define NVDIMM_STAT_ATTR(_name, _stat_id) \
+ struct nvdimm_stat_attr nvdimm_stat_attr_##_name = { \
+ .attr = __ATTR(_name, 0400, nvdimm_stat_attr_show, NULL), \
+ .stat_id = _stat_id, \
+ }
+
+static NVDIMM_STAT_ATTR(media_reads, ND_DIMM_STAT_MEDIA_READS);
+static NVDIMM_STAT_ATTR(media_writes, ND_DIMM_STAT_MEDIA_WRITES);
+static NVDIMM_STAT_ATTR(read_requests, ND_DIMM_STAT_READ_REQUESTS);
+static NVDIMM_STAT_ATTR(write_requests, ND_DIMM_STAT_WRITE_REQUESTS);
+static NVDIMM_STAT_ATTR(total_media_reads, ND_DIMM_STAT_TOTAL_MEDIA_READS);
+static NVDIMM_STAT_ATTR(total_media_writes, ND_DIMM_STAT_TOTAL_MEDIA_WRITES);
+static NVDIMM_STAT_ATTR(total_read_requests, ND_DIMM_STAT_TOTAL_READ_REQUESTS);
+static NVDIMM_STAT_ATTR(total_write_requests, ND_DIMM_STAT_TOTAL_WRITE_REQUESTS);
+
+static struct attribute *nvdimm_stats_attributes[] = {
+ &nvdimm_stat_attr_media_reads.attr.attr,
+ &nvdimm_stat_attr_media_writes.attr.attr,
+ &nvdimm_stat_attr_read_requests.attr.attr,
+ &nvdimm_stat_attr_write_requests.attr.attr,
+ &nvdimm_stat_attr_total_media_reads.attr.attr,
+ &nvdimm_stat_attr_total_media_writes.attr.attr,
+ &nvdimm_stat_attr_total_read_requests.attr.attr,
+ &nvdimm_stat_attr_total_write_requests.attr.attr,
+ NULL,
+};
+
+static const struct attribute_group nvdimm_stats_group = {
+ .name = "stats",
+ .attrs = nvdimm_stats_attributes,
+ .is_visible = nvdimm_stats_visible,
+};
+
static const struct attribute_group nvdimm_firmware_attribute_group = {
.name = "firmware",
.attrs = nvdimm_firmware_attributes,
@@ -565,6 +673,7 @@ static const struct attribute_group *nvdimm_attribute_groups[] = {
&nd_device_attribute_group,
&nvdimm_attribute_group,
&nvdimm_firmware_attribute_group,
+ &nvdimm_stats_group,
NULL,
};
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index 696b55556d4d..ea9e846ae245 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -223,6 +223,11 @@ enum nd_async_mode {
ND_ASYNC,
};
+struct nvdimm_stat_attr {
+ struct device_attribute attr;
+ u64 stat_id;
+};
+
int nd_integrity_init(struct gendisk *disk, unsigned long meta_size);
void wait_nvdimm_bus_probe_idle(struct device *dev);
void nd_device_register(struct device *dev);
diff --git a/include/uapi/linux/ndctl.h b/include/uapi/linux/ndctl.h
index 8cf1e4884fd5..81b76986b423 100644
--- a/include/uapi/linux/ndctl.h
+++ b/include/uapi/linux/ndctl.h
@@ -97,6 +97,31 @@ struct nd_cmd_clear_error {
__u64 cleared;
} __packed;
+/* Various generic dimm stats that can be reported */
+enum {
+ ND_DIMM_STAT_INVALID = 0,
+ ND_DIMM_STAT_MEDIA_READS = 1, /* Media reads after power cycle */
+ ND_DIMM_STAT_MEDIA_WRITES = 2, /* Media writes after power cycle */
+ ND_DIMM_STAT_READ_REQUESTS = 3, /* Read requests after power cycle */
+ ND_DIMM_STAT_WRITE_REQUESTS = 4, /* Write requests after power cycle */
+ ND_DIMM_STAT_TOTAL_MEDIA_READS = 5, /* Total Media Reads */
+ ND_DIMM_STAT_TOTAL_MEDIA_WRITES = 6, /* Total Media Writes */
+ ND_DIMM_STAT_TOTAL_READ_REQUESTS = 7, /* Total Read Requests */
+ ND_DIMM_STAT_TOTAL_WRITE_REQUESTS = 8, /* Total Write Requests */
+ ND_DIMM_STAT_MAX = 8,
+};
+
+struct nd_cmd_get_dimm_stat {
+ /* See enum above for valid values */
+ __u64 stat_id;
+
+ /* Holds a single dimm stat value */
+ union {
+ __s64 int_val;
+ char str_val[120];
+ };
+} __packed;
+
enum {
ND_CMD_IMPLEMENTED = 0,
@@ -117,6 +142,7 @@ enum {
ND_CMD_VENDOR_EFFECT_LOG = 8,
ND_CMD_VENDOR = 9,
ND_CMD_CALL = 10,
+ ND_CMD_GET_STAT = 11,
};
enum {
@@ -151,6 +177,7 @@ static inline const char *nvdimm_cmd_name(unsigned cmd)
case ND_CMD_VENDOR_EFFECT_LOG: return "effect_log";
case ND_CMD_VENDOR: return "vendor";
case ND_CMD_CALL: return "cmd_call";
+ case ND_CMD_GET_STAT: return "get_stat";
default: return "unknown";
}
}
--
2.28.0
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