[Devel] [PATCH RH8 2/3] target: add histogram for LUN statistics

Andrey Zhadchenko andrey.zhadchenko at virtuozzo.com
Mon Apr 26 10:18:12 MSK 2021


From: Andrey Grafin <Andrey.Grafin at acronis.com>

This patch adds histogram statistics to scsi_ports_stats.
Histogram can be obtained and configured via config_fs.
Histogram measurement unit is usec.

Histogram usage:
1. Configure histogram '| 1 ms | 10 ms | 15 ms | largest values |'
    `echo "1000 10000 15000" > target/iscsi/iqn.2003-01.org.linux-iscsi.localhost.x8664\:sn.fdee138936b9/tpgt_1/lun/lun_3/statistics/scsi_tgt_port/write_hist`

2. Obtain histogram stats
    `cat /target/iscsi/iqn.2003-01.org.linux-iscsi.localhost.x8664\:sn.fdee138936b9/tpgt_1/lun/lun_3/statistics/scsi_tgt_port/write_hist`

3. Stop histogram stats
    `echo "" > /target/iscsi/iqn.2003-01.org.linux-iscsi.localhost.x8664\:sn.fdee138936b9/tpgt_1/lun/lun_3/statistics/scsi_tgt_port/write_hist`

Signed-off-by: Andrey Grafin <Andrey.Grafin at acronis.com>
Acked-by: Andrei Vagin <avagin at virtuozzo.com>

(cherry picked from dcec5ba86d70452dc79f30261c0e217ff2c253bd)
Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
---
 drivers/target/target_core_stat.c      | 206 +++++++++++++++++++++++++++++++++
 drivers/target/target_core_tpg.c       |  19 +++
 drivers/target/target_core_transport.c |  25 ++++
 include/target/target_core_base.h      |  16 +++
 4 files changed, 266 insertions(+)

diff --git a/drivers/target/target_core_stat.c b/drivers/target/target_core_stat.c
index 844d076..07ce36e 100644
--- a/drivers/target/target_core_stat.c
+++ b/drivers/target/target_core_stat.c
@@ -33,6 +33,7 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/configfs.h>
+#include <linux/ctype.h>
 
 #include <target/target_core_base.h>
 #include <target/target_core_backend.h>
@@ -537,6 +538,208 @@ static struct se_lun *to_stat_tgt_port(struct config_item *item)
 	return container_of(pgrps, struct se_lun, port_stat_grps);
 }
 
+#define DEV_STAT_TGT_PORT_SHOW_HIST(_name)				\
+static ssize_t target_stat_tgt_port_##_name##_show(			\
+	struct config_item *item, char *page)				\
+{									\
+	ssize_t size = -ENODEV;						\
+	struct se_device *dev;						\
+	struct se_lun *lun = to_stat_port(item);			\
+									\
+	rcu_read_lock();						\
+	dev = rcu_dereference(lun->lun_se_dev);				\
+	if (dev) {							\
+		size = snprintf_histogram(page, PAGE_SIZE,		\
+			rcu_dereference(lun->lun_stats._name));		\
+	}								\
+	rcu_read_unlock();						\
+	return size;							\
+}
+
+#define DEV_STAT_TGT_PORT_STORE_HIST(_name)				\
+static ssize_t target_stat_tgt_port_##_name##_store(			\
+	struct config_item *item, const char *page, size_t size)	\
+{									\
+	struct se_device *dev;						\
+	struct se_lun *lun = to_stat_port(item);			\
+	struct scsi_port_stats_hist *old, *new;				\
+	ssize_t ret;							\
+									\
+	new = kzalloc(sizeof(*new), GFP_KERNEL);			\
+	if (!new)							\
+		return -ENOMEM;						\
+									\
+	ret = read_histogram_items(page,				\
+		size, new->items, TCM_SE_PORT_STATS_HIST_MAX - 1);	\
+									\
+	if (ret < 0)							\
+		goto err;						\
+									\
+	if (ret == 0) {							\
+		kfree(new);						\
+		new = NULL;						\
+	} else	{							\
+		new->items[ret] = U64_MAX;				\
+		new->count = ret + 1;					\
+	}								\
+									\
+	rcu_read_lock();						\
+	dev = rcu_dereference(lun->lun_se_dev);				\
+									\
+	if (!dev) {							\
+		rcu_read_unlock();					\
+		ret = -ENODEV;						\
+		goto err;						\
+	}								\
+									\
+	old = rcu_dereference(lun->lun_stats._name);			\
+	rcu_assign_pointer(lun->lun_stats._name, new);			\
+									\
+	rcu_read_unlock();						\
+									\
+	if (old)							\
+		kfree_rcu(old, rcu_head);				\
+									\
+	return size;							\
+									\
+err:									\
+	if (new)							\
+		kfree(new);						\
+	return ret;							\
+}
+
+static void scsi_port_stats_hist_observe_bsearch(
+		struct scsi_port_stats_hist *hist, u64 val)
+{
+	size_t start = 0, end = hist->count - 1;
+
+	while (start < end) {
+		size_t mid = start + (end - start) / 2;
+
+		if (val < hist->items[mid])
+			end = mid;
+		else
+			start = mid + 1;
+	}
+
+	atomic64_inc(&hist->counters[start]);
+}
+
+void scsi_port_stats_hist_observe(
+		struct scsi_port_stats_hist *hist, u64 val)
+{
+	if (!hist)
+		return;
+
+	scsi_port_stats_hist_observe_bsearch(hist, val);
+}
+
+static ssize_t find_token(const char *page, size_t size,
+		size_t offset, size_t *token_len)
+{
+	size_t i;
+	ssize_t pos = -1;
+	size_t len = 0;
+
+	BUG_ON(offset > size);
+
+	for (i = offset; i < size; ++i) {
+		if (isspace(page[i])) {
+			if (len)
+				break;
+		} else if (!len++) {
+			pos = i;
+		}
+	}
+
+	if (pos > -1)
+		*token_len = len;
+
+	return pos;
+}
+
+static ssize_t read_histogram_items(const char *page, size_t size,
+		u64 *items, u8 items_max)
+{
+	u8 total = 0;
+	size_t token_len = 0;
+	ssize_t pos;
+
+	if (size == 0)
+		return 0;
+
+	pos = find_token(page, size, 0, &token_len);
+	if (pos == -1)
+		return 0;
+
+	while (pos != -1) {
+		int ret;
+		char buf[64];
+		u64 item;
+
+		if (token_len >= sizeof(buf))
+			return -EINVAL;
+
+		if (total == items_max) {
+			pr_err("items count can't be greater than %d: %d",
+					items_max, -EPERM);
+			return -EINVAL;
+		}
+
+		memcpy(buf, page + pos, token_len);
+		buf[token_len] = 0;
+
+		ret = kstrtou64(buf, 10, &item);
+		if (ret < 0) {
+			pr_err("kstrtou64() failed for an item '%s': %d",
+					buf, ret);
+			return ret;
+		}
+
+		if ((item <= 0) || (total && item <= items[total - 1])) {
+			pr_err("items must be positive, unique and sorted: %d",
+					-EINVAL);
+			return -EINVAL;
+		}
+
+		items[total++] = item;
+		pos = find_token(page, size, pos + token_len, &token_len);
+	}
+
+	return total;
+}
+
+static ssize_t snprintf_histogram(char *page, size_t size,
+		struct scsi_port_stats_hist *hist)
+{
+	ssize_t ret = 0;
+	u8 i;
+
+	if (!hist)
+		return 0;
+
+	for (i = 0; i < hist->count - 1; ++i)
+		ret += snprintf(page + ret, PAGE_SIZE - ret,
+			"%llu ", (u64)atomic64_read(&hist->counters[i]));
+
+	ret += snprintf(page + ret, PAGE_SIZE - ret,
+		"%llu\n", (u64)atomic64_read(&hist->counters[i]));
+
+	return ret;
+}
+
+DEV_STAT_TGT_PORT_STORE_HIST(read_hist);
+DEV_STAT_TGT_PORT_SHOW_HIST(read_hist);
+CONFIGFS_ATTR(target_stat_tgt_port_, read_hist);
+
+DEV_STAT_TGT_PORT_STORE_HIST(write_hist);
+DEV_STAT_TGT_PORT_SHOW_HIST(write_hist);
+CONFIGFS_ATTR(target_stat_tgt_port_, write_hist);
+
+DEV_STAT_TGT_PORT_STORE_HIST(sync_hist);
+DEV_STAT_TGT_PORT_SHOW_HIST(sync_hist);
+CONFIGFS_ATTR(target_stat_tgt_port_, sync_hist);
+
 static ssize_t target_stat_tgt_port_inst_show(struct config_item *item,
 		char *page)
 {
@@ -754,6 +957,9 @@ static ssize_t target_stat_tgt_port_hs_in_cmds_show(struct config_item *item,
 	&target_stat_tgt_port_attr_bidi_errors,
 	&target_stat_tgt_port_attr_aborts,
 	&target_stat_tgt_port_attr_queue_cmds,
+	&target_stat_tgt_port_attr_read_hist,
+	&target_stat_tgt_port_attr_write_hist,
+	&target_stat_tgt_port_attr_sync_hist,
 	NULL,
 };
 
diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index 6894778..17f506c 100644
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -634,6 +634,7 @@ void core_tpg_remove_lun(
 	 * reference to se_device->dev_group.
 	 */
 	struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);
+	struct scsi_port_stats_hist *write_hist, *read_hist, *sync_hist;
 
 	lun->lun_shutdown = true;
 
@@ -662,5 +663,23 @@ void core_tpg_remove_lun(
 	lun->lun_shutdown = false;
 	mutex_unlock(&tpg->tpg_lun_mutex);
 
+	write_hist = rcu_dereference(lun->lun_stats.write_hist);
+	rcu_assign_pointer(lun->lun_stats.write_hist, NULL);
+
+	read_hist = rcu_dereference(lun->lun_stats.read_hist);
+	rcu_assign_pointer(lun->lun_stats.read_hist, NULL);
+
+	sync_hist = rcu_dereference(lun->lun_stats.sync_hist);
+	rcu_assign_pointer(lun->lun_stats.sync_hist, NULL);
+
+	if (write_hist)
+		kfree_rcu(write_hist, rcu_head);
+
+	if (read_hist)
+		kfree_rcu(read_hist, rcu_head);
+
+	if (sync_hist)
+		kfree_rcu(sync_hist, rcu_head);
+
 	percpu_ref_exit(&lun->lun_ref);
 }
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index f5afe9f..243e2a0 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -888,6 +888,9 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
 	cmd->transport_state |= (CMD_T_COMPLETE | CMD_T_ACTIVE);
 	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
 
+	if (success)
+		cmd->finished_exec_at = ktime_get_ns() / NSEC_PER_USEC;
+
 	INIT_WORK(&cmd->work, success ? target_complete_ok_work :
 		  target_complete_failure_work);
 	if (cmd->se_cmd_flags & SCF_USE_CPUID)
@@ -1991,6 +1994,7 @@ void __target_execute_cmd(struct se_cmd *cmd, bool do_checks)
 		}
 	}
 
+	cmd->started_exec_at = ktime_get_ns() / NSEC_PER_USEC;
 	ret = cmd->execute_cmd(cmd);
 	if (!ret)
 		return;
@@ -2373,6 +2377,15 @@ static void target_complete_ok_work(struct work_struct *work)
 	}
 
 queue_rsp:
+	if (cmd->t_task_cdb[0] == SYNCHRONIZE_CACHE ||
+		cmd->t_task_cdb[0] == SYNCHRONIZE_CACHE_16) {
+		rcu_read_lock();
+		scsi_port_stats_hist_observe(
+			rcu_dereference(cmd->se_lun->lun_stats.sync_hist),
+			cmd->finished_exec_at - cmd->started_exec_at);
+		rcu_read_unlock();
+	}
+
 	switch (cmd->data_direction) {
 	case DMA_FROM_DEVICE:
 		/*
@@ -2394,6 +2407,12 @@ static void target_complete_ok_work(struct work_struct *work)
 
 		atomic_long_inc(&cmd->se_lun->lun_stats.read_cmds);
 
+		rcu_read_lock();
+		scsi_port_stats_hist_observe(
+			rcu_dereference(cmd->se_lun->lun_stats.read_hist),
+			cmd->finished_exec_at - cmd->started_exec_at);
+		rcu_read_unlock();
+
 		/*
 		 * Perform READ_STRIP of PI using software emulation when
 		 * backend had PI enabled, if the transport will not be
@@ -2423,6 +2442,12 @@ static void target_complete_ok_work(struct work_struct *work)
 			atomic_long_inc(&cmd->se_lun->lun_stats.bidi_cmds) :
 			atomic_long_inc(&cmd->se_lun->lun_stats.write_cmds);
 
+		rcu_read_lock();
+		scsi_port_stats_hist_observe(
+			rcu_dereference(cmd->se_lun->lun_stats.write_hist),
+			cmd->finished_exec_at - cmd->started_exec_at);
+		rcu_read_unlock();
+
 		/*
 		 * Check if we need to send READ payload for BIDI-COMMAND
 		 */
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 1d1f3a9..82a87ce 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -541,6 +541,8 @@ struct se_cmd {
 	sense_reason_t		pi_err;
 	sector_t		bad_sector;
 	int			cpuid;
+	u64			started_exec_at;
+	u64			finished_exec_at;
 };
 
 struct se_ua {
@@ -711,6 +713,17 @@ struct se_port_stat_grps {
 	struct config_group scsi_transport_group;
 };
 
+#define TCM_SE_PORT_STATS_HIST_MAX	40
+
+struct scsi_port_stats_hist {
+	u64		items[TCM_SE_PORT_STATS_HIST_MAX];
+	atomic64_t	counters[TCM_SE_PORT_STATS_HIST_MAX];
+	u8		count;
+	struct rcu_head	rcu_head;
+};
+
+void scsi_port_stats_hist_observe(struct scsi_port_stats_hist *hist, u64 val);
+
 struct scsi_port_stats {
 	atomic_long_t	cmd_pdus;
 	atomic_long_t	tx_data_octets;
@@ -723,6 +736,9 @@ struct scsi_port_stats {
 	atomic_long_t	bidi_errors;
 	atomic_long_t	queue_cmds;
 	atomic_long_t	aborts;
+	struct scsi_port_stats_hist __rcu	*read_hist;
+	struct scsi_port_stats_hist __rcu	*write_hist;
+	struct scsi_port_stats_hist __rcu	*sync_hist;
 };
 
 struct se_lun {
-- 
1.8.3.1



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