[PATCHv3 5/9] libnvme: add support for retrieving namespace gendisk I/O statistics
Nilay Shroff
nilay at linux.ibm.com
Tue Apr 21 07:50:26 PDT 2026
Gendisk I/O statistics provide useful insight into disk activity,
including read/write/discard/flush operations, as well as information
about in-flight I/Os and I/O timing.
Parsing these statistics allows users to determine the number of I/Os
processed, time spent servicing I/O, number of sectors accessed, and
the count of in-flight requests.
Add support for retrieving namespace gendisk I/O statistics. Also add
support for computing deltas of these statistics between samples, such
as I/O ticks, number of sectors, and number of serviced I/Os.
These metrics can be used by tools such as nvme-top to display real-time
disk activity.
Signed-off-by: Nilay Shroff <nilay at linux.ibm.com>
---
libnvme/src/libnvme.ld | 11 +++
libnvme/src/nvme/private.h | 5 ++
libnvme/src/nvme/tree.c | 142 +++++++++++++++++++++++++++++++++++++
libnvme/src/nvme/tree.h | 93 ++++++++++++++++++++++++
4 files changed, 251 insertions(+)
diff --git a/libnvme/src/libnvme.ld b/libnvme/src/libnvme.ld
index 6b7a08cb5..ce85c960e 100644
--- a/libnvme/src/libnvme.ld
+++ b/libnvme/src/libnvme.ld
@@ -129,6 +129,17 @@ LIBNVME_3 {
libnvme_ns_get_serial;
libnvme_ns_get_subsystem;
libnvme_ns_get_uuid;
+ libnvme_ns_reset_stat;
+ libnvme_ns_update_stat;
+ libnvme_ns_get_stat_interval;
+ libnvme_ns_get_read_ios;
+ libnvme_ns_get_write_ios;
+ libnvme_ns_get_read_ticks;
+ libnvme_ns_get_write_ticks;
+ libnvme_ns_get_read_sectors;
+ libnvme_ns_get_write_sectors;
+ libnvme_ns_get_inflights;
+ libnvme_ns_get_io_ticks;
libnvme_ns_identify;
libnvme_ns_read;
libnvme_ns_verify;
diff --git a/libnvme/src/nvme/private.h b/libnvme/src/nvme/private.h
index 818303d85..08b35e002 100644
--- a/libnvme/src/nvme/private.h
+++ b/libnvme/src/nvme/private.h
@@ -227,6 +227,11 @@ struct libnvme_ns { // !generate-accessors
struct libnvme_ns_head *head;
struct libnvme_global_ctx *ctx;
+
+ struct libnvme_stat stat[2]; /* gendisk I/O stat */
+ unsigned int curr_idx; /* current index into the stat[] */
+ bool diffstat; //!accessors:none
+
struct libnvme_transport_handle *hdl;
__u32 nsid;
char *name;
diff --git a/libnvme/src/nvme/tree.c b/libnvme/src/nvme/tree.c
index 6a05ae994..ca716bde7 100644
--- a/libnvme/src/nvme/tree.c
+++ b/libnvme/src/nvme/tree.c
@@ -900,6 +900,21 @@ __public void libnvme_path_reset_stat(libnvme_path_t p)
memset(stat, 0, 2 * sizeof(struct libnvme_stat));
}
+static libnvme_stat_t libnvme_ns_get_stat(libnvme_ns_t n, unsigned int idx)
+{
+ if (idx > 1)
+ return NULL;
+
+ return &n->stat[idx];
+}
+
+__public void libnvme_ns_reset_stat(libnvme_ns_t n)
+{
+ libnvme_stat_t stat = &n->stat[0];
+
+ memset(stat, 0, 2 * sizeof(struct libnvme_stat));
+}
+
static int libnvme_update_stat(const char *sysfs_stat_path, libnvme_stat_t stat)
{
int n;
@@ -974,6 +989,24 @@ __public int libnvme_path_update_stat(libnvme_path_t p, bool diffstat)
return libnvme_update_stat(sysfs_stat_path, stat);
}
+__public int libnvme_ns_update_stat(libnvme_ns_t n, bool diffstat)
+{
+ __cleanup_free char *sysfs_stat_path = NULL;
+ libnvme_stat_t stat;
+
+ n->diffstat = diffstat;
+ n->curr_idx ^= 1;
+ stat = libnvme_ns_get_stat(n, n->curr_idx);
+ if (!stat)
+ return -EINVAL;
+
+ sysfs_stat_path = libnvme_get_ns_attr(n, "stat");
+ if (!sysfs_stat_path)
+ return -EINVAL;
+
+ return libnvme_update_stat(sysfs_stat_path, stat);
+}
+
static int libnvme_stat_get_inflights(libnvme_stat_t stat)
{
return stat->inflights;
@@ -990,6 +1023,17 @@ __public unsigned int libnvme_path_get_inflights(libnvme_path_t p)
return libnvme_stat_get_inflights(curr);
}
+__public unsigned int libnvme_ns_get_inflights(libnvme_ns_t n)
+{
+ libnvme_stat_t curr;
+
+ curr = libnvme_ns_get_stat(n, n->curr_idx);
+ if (!curr)
+ return 0;
+
+ return libnvme_stat_get_inflights(curr);
+}
+
static int libnvme_stat_get_io_ticks(libnvme_stat_t curr, libnvme_stat_t prev,
bool diffstat)
{
@@ -1017,6 +1061,19 @@ __public unsigned int libnvme_path_get_io_ticks(libnvme_path_t p)
return libnvme_stat_get_io_ticks(curr, prev, p->diffstat);
}
+__public unsigned int libnvme_ns_get_io_ticks(libnvme_ns_t n)
+{
+ libnvme_stat_t curr, prev;
+
+ curr = libnvme_ns_get_stat(n, n->curr_idx);
+ prev = libnvme_ns_get_stat(n, !n->curr_idx);
+
+ if (!curr || !prev)
+ return 0;
+
+ return libnvme_stat_get_io_ticks(curr, prev, n->diffstat);
+}
+
static unsigned int libnvme_stat_get_ticks(libnvme_stat_t curr,
libnvme_stat_t prev, enum libnvme_stat_group grp, bool diffstat)
{
@@ -1055,6 +1112,30 @@ __public unsigned int libnvme_path_get_write_ticks(libnvme_path_t p)
return __libnvme_path_get_ticks(p, WRITE);
}
+static unsigned int __libnvme_ns_get_ticks(libnvme_ns_t n,
+ enum libnvme_stat_group grp)
+{
+ libnvme_stat_t curr, prev;
+
+ curr = libnvme_ns_get_stat(n, n->curr_idx);
+ prev = libnvme_ns_get_stat(n, !n->curr_idx);
+
+ if (!curr || !prev)
+ return 0;
+
+ return libnvme_stat_get_ticks(curr, prev, grp, n->diffstat);
+}
+
+__public unsigned int libnvme_ns_get_read_ticks(libnvme_ns_t n)
+{
+ return __libnvme_ns_get_ticks(n, READ);
+}
+
+__public unsigned int libnvme_ns_get_write_ticks(libnvme_ns_t n)
+{
+ return __libnvme_ns_get_ticks(n, WRITE);
+}
+
static double libnvme_stat_get_interval(libnvme_stat_t curr,
libnvme_stat_t prev)
{
@@ -1079,6 +1160,19 @@ __public double libnvme_path_get_stat_interval(libnvme_path_t p)
return libnvme_stat_get_interval(curr, prev);
}
+__public double libnvme_ns_get_stat_interval(libnvme_ns_t n)
+{
+ libnvme_stat_t curr, prev;
+
+ curr = libnvme_ns_get_stat(n, n->curr_idx);
+ prev = libnvme_ns_get_stat(n, !n->curr_idx);
+
+ if (!curr || !prev)
+ return 0;
+
+ return libnvme_stat_get_interval(curr, prev);
+}
+
static unsigned long libnvme_stat_get_ios(libnvme_stat_t curr,
libnvme_stat_t prev, enum libnvme_stat_group grp, bool diffstat)
{
@@ -1117,6 +1211,30 @@ __public unsigned long libnvme_path_get_write_ios(libnvme_path_t p)
return __libnvme_path_get_ios(p, WRITE);
}
+static unsigned long __libnvme_ns_get_ios(libnvme_ns_t n,
+ enum libnvme_stat_group grp)
+{
+ libnvme_stat_t curr, prev;
+
+ curr = libnvme_ns_get_stat(n, n->curr_idx);
+ prev = libnvme_ns_get_stat(n, !n->curr_idx);
+
+ if (!curr || !prev)
+ return 0;
+
+ return libnvme_stat_get_ios(curr, prev, grp, n->diffstat);
+}
+
+__public unsigned long libnvme_ns_get_read_ios(libnvme_ns_t n)
+{
+ return __libnvme_ns_get_ios(n, READ);
+}
+
+__public unsigned long libnvme_ns_get_write_ios(libnvme_ns_t n)
+{
+ return __libnvme_ns_get_ios(n, WRITE);
+}
+
static unsigned long long libnvme_stat_get_sectors(libnvme_stat_t curr,
libnvme_stat_t prev, enum libnvme_stat_group grp, bool diffstat)
{
@@ -1155,6 +1273,30 @@ __public unsigned long long libnvme_path_get_write_sectors(libnvme_path_t p)
return __libnvme_path_get_sectors(p, WRITE);
}
+static unsigned long long __libnvme_ns_get_sectors(libnvme_ns_t n,
+ enum libnvme_stat_group grp)
+{
+ libnvme_stat_t curr, prev;
+
+ curr = libnvme_ns_get_stat(n, n->curr_idx);
+ prev = libnvme_ns_get_stat(n, !n->curr_idx);
+
+ if (!curr || !prev)
+ return 0;
+
+ return libnvme_stat_get_sectors(curr, prev, grp, n->diffstat);
+}
+
+__public unsigned long long libnvme_ns_get_read_sectors(libnvme_ns_t n)
+{
+ return __libnvme_ns_get_sectors(n, READ);
+}
+
+__public unsigned long long libnvme_ns_get_write_sectors(libnvme_ns_t n)
+{
+ return __libnvme_ns_get_sectors(n, WRITE);
+}
+
void nvme_free_path(struct libnvme_path *p)
{
if (!p)
diff --git a/libnvme/src/nvme/tree.h b/libnvme/src/nvme/tree.h
index b46c3c4c2..a166d9df6 100644
--- a/libnvme/src/nvme/tree.h
+++ b/libnvme/src/nvme/tree.h
@@ -853,6 +853,99 @@ libnvme_subsystem_t libnvme_ctrl_get_subsystem(libnvme_ctrl_t c);
*/
const char *libnvme_ns_head_get_sysfs_dir(libnvme_ns_head_t head);
+/**
+ * libnvme_ns_update_stat() - update the nvme namespace stat
+ * @n: &libnvme_ns_t object
+ * @diffstat: If set to true then getters return the diff stat otherwise
+ * return the current absolute stat
+ *
+ * Returns: 0 on success, -1 on error
+ */
+int libnvme_ns_update_stat(libnvme_ns_t n, bool diffstat);
+
+/**
+ * libnvme_ns_reset_stat() - Resets nvme namespace stat
+ * @n: &libnvme_ns_t object
+ *
+ */
+void libnvme_ns_reset_stat(libnvme_ns_t n);
+
+/**
+ * libnvme_ns_get_inflights() - Inflight IOs for nvme_ns_t object
+ * @n: &libnvme_ns_t object
+ *
+ * Return: Inflight number of IOs
+ */
+unsigned int libnvme_ns_get_inflights(libnvme_ns_t n);
+
+/**
+ * libnvme_ns_get_io_ticks() - Get IO ticks
+ * @n: &libnvme_ns_t object
+ *
+ * Return: Time consumed, in milliseconds, processing I/O requests between
+ * two stat samples
+ */
+unsigned int libnvme_ns_get_io_ticks(libnvme_ns_t n);
+
+/**
+ * libnvme_ns_get_read_ticks() - Get read I/O ticks
+ * @n: &libnvme_ns_t object
+ *
+ * Return: Time, in milliseconds, sepnt processing read I/O requests
+ * between two stat samples
+ */
+unsigned int libnvme_ns_get_read_ticks(libnvme_ns_t n);
+
+/**
+ * libnvme_ns_get_write_ticks() - Get write I/O ticks
+ * @n: &libnvme_ns_t object
+ *
+ * Return: Time, in milliseconds, sepnt processing write I/O requests
+ * between two stat samples
+ */
+unsigned int libnvme_ns_get_write_ticks(libnvme_ns_t n);
+
+/**
+ * libnvme_ns_get_stat_interval() - Get interval between two stat samples
+ * @n: &libnvme_ns_t object
+ *
+ * Return: Interval, in milliseconds, between collection of two consecutive
+ * stat samples
+ */
+double libnvme_ns_get_stat_interval(libnvme_ns_t n);
+
+/**
+ * libnvme_ns_get_read_ios() - Get num of read I/Os
+ * @n: &libnvme_ns_t object
+ *
+ * Return: Num of read IOs processed between two stat samples
+ */
+unsigned long libnvme_ns_get_read_ios(libnvme_ns_t n);
+
+/**
+ * libnvme_ns_get_write_ios() - Get num of write I/Os
+ * @n: &libnvme_ns_t object
+ *
+ * Return: Num of write IOs processed between two consecutive stat samples
+ */
+unsigned long libnvme_ns_get_write_ios(libnvme_ns_t n);
+
+/**
+ * libnvme_ns_get_read_sectors() - Get num of read sectors
+ * @n: &libnvme_ns_t object
+ *
+ * Return: Num of sectors read from the device between two stat samples
+ */
+unsigned long long libnvme_ns_get_read_sectors(libnvme_ns_t n);
+
+/**
+ * libnvme_ns_get_write_sectors() - Get num of write sectors
+ * @n: &libnvme_ns_t object
+ *
+ * Return: Num of sectors written to the device between two stat samples
+ */
+unsigned long long libnvme_ns_get_write_sectors(libnvme_ns_t n);
+
/**
* libnvme_ctrl_identify() - Issues an 'identify controller' command
* @c: Controller instance
--
2.53.0
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