diff mbox series

[v3] ceph: add min/max latency support for read/write/metadata metrics

Message ID 1584403206-17862-1-git-send-email-xiubli@redhat.com (mailing list archive)
State New, archived
Headers show
Series [v3] ceph: add min/max latency support for read/write/metadata metrics | expand

Commit Message

Xiubo Li March 17, 2020, midnight UTC 
From: Xiubo Li <xiubli@redhat.com>

These will be very useful help diagnose problems.

URL: https://tracker.ceph.com/issues/44533
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---

Changed in V2:
- switch spin lock to cmpxchg

Changed in V3:
- add the __update_min/max_latency helpers
- minor fix

 fs/ceph/debugfs.c    | 26 +++++++++++++++++++++-----
 fs/ceph/mds_client.c |  9 +++++++++
 fs/ceph/metric.h     | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 79 insertions(+), 8 deletions(-)

Comments

Jeffrey Layton March 17, 2020, 11:12 a.m. UTC | #1 
On Mon, 2020-03-16 at 20:00 -0400, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
> 
> These will be very useful help diagnose problems.
> 
> URL: https://tracker.ceph.com/issues/44533
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
> 
> Changed in V2:
> - switch spin lock to cmpxchg
> 
> Changed in V3:
> - add the __update_min/max_latency helpers
> - minor fix
> 
>  fs/ceph/debugfs.c    | 26 +++++++++++++++++++++-----
>  fs/ceph/mds_client.c |  9 +++++++++
>  fs/ceph/metric.h     | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
>  3 files changed, 79 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
> index 60f3e307..bcf7215 100644
> --- a/fs/ceph/debugfs.c
> +++ b/fs/ceph/debugfs.c
> @@ -130,27 +130,43 @@ static int metric_show(struct seq_file *s, void *p)
>  	struct ceph_mds_client *mdsc = fsc->mdsc;
>  	int i, nr_caps = 0;
>  	s64 total, sum, avg = 0;
> +	unsigned long min, max;
>  
> -	seq_printf(s, "item          total       sum_lat(us)     avg_lat(us)\n");
> -	seq_printf(s, "-----------------------------------------------------\n");
> +	seq_printf(s, "item          total       sum_lat(us)     avg_lat(us)     min_lat(us)     max_lat(us)\n");
> +	seq_printf(s, "-------------------------------------------------------------------------------------\n");
>  
>  	total = percpu_counter_sum(&mdsc->metric.total_reads);
>  	sum = percpu_counter_sum(&mdsc->metric.read_latency_sum);
>  	sum = jiffies_to_usecs(sum);
>  	avg = total ? sum / total : 0;
> -	seq_printf(s, "%-14s%-12lld%-16lld%lld\n", "read", total, sum, avg);
> +	min = atomic_long_read(&mdsc->metric.read_latency_min);
> +	min = jiffies_to_usecs(min == ULONG_MAX ? 0 : min);
> +	max = atomic_long_read(&mdsc->metric.read_latency_max);
> +	max = jiffies_to_usecs(max);
> +	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16ld%ld\n", "read",
> +		   total, sum, avg, min, max);
>  
>  	total = percpu_counter_sum(&mdsc->metric.total_writes);
>  	sum = percpu_counter_sum(&mdsc->metric.write_latency_sum);
>  	sum = jiffies_to_usecs(sum);
>  	avg = total ? sum / total : 0;
> -	seq_printf(s, "%-14s%-12lld%-16lld%lld\n", "write", total, sum, avg);
> +	min = atomic_long_read(&mdsc->metric.write_latency_min);
> +	min = jiffies_to_usecs(min == ULONG_MAX ? 0 : min);
> +	max = atomic_long_read(&mdsc->metric.write_latency_max);
> +	max = jiffies_to_usecs(max);
> +	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16ld%ld\n", "write",
> +		   total, sum, avg, min, max);
>  
>  	total = percpu_counter_sum(&mdsc->metric.total_metadatas);
>  	sum = percpu_counter_sum(&mdsc->metric.metadata_latency_sum);
>  	sum = jiffies_to_usecs(sum);
>  	avg = total ? sum / total : 0;
> -	seq_printf(s, "%-14s%-12lld%-16lld%lld\n", "metadata", total, sum, avg);
> +	min = atomic_long_read(&mdsc->metric.metadata_latency_min);
> +	min = jiffies_to_usecs(min == ULONG_MAX ? 0 : min);
> +	max = atomic_long_read(&mdsc->metric.metadata_latency_max);
> +	max = jiffies_to_usecs(max);
> +	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16ld%ld\n", "metadata",
> +		   total, sum, avg, min, max);
>  
>  	seq_printf(s, "\n");
>  	seq_printf(s, "item          total           miss            hit\n");
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 5c03ed3..7844aa6 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -4358,6 +4358,9 @@ static int ceph_mdsc_metric_init(struct ceph_client_metric *metric)
>  	if (ret)
>  		goto err_read_latency_sum;
>  
> +	atomic_long_set(&metric->read_latency_min, ULONG_MAX);
> +	atomic_long_set(&metric->read_latency_max, 0);
> +
>  	ret = percpu_counter_init(&metric->total_writes, 0, GFP_KERNEL);
>  	if (ret)
>  		goto err_total_writes;
> @@ -4366,6 +4369,9 @@ static int ceph_mdsc_metric_init(struct ceph_client_metric *metric)
>  	if (ret)
>  		goto err_write_latency_sum;
>  
> +	atomic_long_set(&metric->write_latency_min, ULONG_MAX);
> +	atomic_long_set(&metric->write_latency_max, 0);
> +
>  	ret = percpu_counter_init(&metric->total_metadatas, 0, GFP_KERNEL);
>  	if (ret)
>  		goto err_total_metadatas;
> @@ -4374,6 +4380,9 @@ static int ceph_mdsc_metric_init(struct ceph_client_metric *metric)
>  	if (ret)
>  		goto err_metadata_latency_sum;
>  
> +	atomic_long_set(&metric->metadata_latency_min, ULONG_MAX);
> +	atomic_long_set(&metric->metadata_latency_max, 0);
> +
>  	return 0;
>  
>  err_metadata_latency_sum:
> diff --git a/fs/ceph/metric.h b/fs/ceph/metric.h
> index faba142..c9c76d5 100644
> --- a/fs/ceph/metric.h
> +++ b/fs/ceph/metric.h
> @@ -2,6 +2,10 @@
>  #ifndef _FS_CEPH_MDS_METRIC_H
>  #define _FS_CEPH_MDS_METRIC_H
>  
> +#include <linux/atomic.h>
> +#include <linux/percpu.h>
> +#include <linux/spinlock.h>
> +
>  /* This is the global metrics */
>  struct ceph_client_metric {
>  	atomic64_t            total_dentries;
> @@ -13,12 +17,18 @@ struct ceph_client_metric {
>  
>  	struct percpu_counter total_reads;
>  	struct percpu_counter read_latency_sum;
> +	atomic_long_t read_latency_min;
> +	atomic_long_t read_latency_max;
>  
>  	struct percpu_counter total_writes;
>  	struct percpu_counter write_latency_sum;
> +	atomic_long_t write_latency_min;
> +	atomic_long_t write_latency_max;
>  
>  	struct percpu_counter total_metadatas;
>  	struct percpu_counter metadata_latency_sum;
> +	atomic_long_t metadata_latency_min;
> +	atomic_long_t metadata_latency_max;
>  };
>  
>  static inline void ceph_update_cap_hit(struct ceph_client_metric *m)
> @@ -31,16 +41,44 @@ static inline void ceph_update_cap_mis(struct ceph_client_metric *m)
>  	percpu_counter_inc(&m->i_caps_mis);
>  }
>  
> +static inline void __update_min_latency(atomic_long_t *min, unsigned long lat)

nit: I don't see a need for the double-underscore prefix here.

> +{
> +	unsigned long cur, old;
> +
> +	cur = atomic_long_read(min);
> +	do {
> +		old = cur;
> +		if (likely(lat >= old))
> +			break;
> +	} while ((cur = atomic_long_cmpxchg(min, old, lat)) != old);
> +}
> +
> +static inline void __update_max_latency(atomic_long_t *max, unsigned long lat)
> +{
> +	unsigned long cur, old;
> +
> +	cur = atomic_long_read(max);
> +	do {
> +		old = cur;
> +		if (likely(lat <= old))
> +			break;
> +	} while ((cur = atomic_long_cmpxchg(max, old, lat)) != old);
> +}
> +
>  static inline void ceph_update_read_latency(struct ceph_client_metric *m,
>  					    unsigned long r_start,
>  					    unsigned long r_end,
>  					    int rc)
>  {
> +	unsigned long lat = r_end - r_start;
> +
>  	if (rc < 0 && rc != -ENOENT && rc != -ETIMEDOUT)
>  		return;
>  
>  	percpu_counter_inc(&m->total_reads);
> -	percpu_counter_add(&m->read_latency_sum, r_end - r_start);
> +	percpu_counter_add(&m->read_latency_sum, lat);
> +	__update_min_latency(&m->read_latency_min, lat);
> +	__update_max_latency(&m->read_latency_max, lat);
>  }
>  
>  static inline void ceph_update_write_latency(struct ceph_client_metric *m,
> @@ -48,11 +86,15 @@ static inline void ceph_update_write_latency(struct ceph_client_metric *m,
>  					     unsigned long r_end,
>  					     int rc)
>  {
> +	unsigned long lat = r_end - r_start;
> +
>  	if (rc && rc != -ETIMEDOUT)
>  		return;
>  
>  	percpu_counter_inc(&m->total_writes);
> -	percpu_counter_add(&m->write_latency_sum, r_end - r_start);
> +	percpu_counter_add(&m->write_latency_sum, lat);
> +	__update_min_latency(&m->write_latency_min, lat);
> +	__update_max_latency(&m->write_latency_max, lat);
>  }
>  
>  static inline void ceph_update_metadata_latency(struct ceph_client_metric *m,
> @@ -60,10 +102,14 @@ static inline void ceph_update_metadata_latency(struct ceph_client_metric *m,
>  						unsigned long r_end,
>  						int rc)
>  {
> +	unsigned long lat = r_end - r_start;
> +
>  	if (rc && rc != -ENOENT)
>  		return;
>  
>  	percpu_counter_inc(&m->total_metadatas);
> -	percpu_counter_add(&m->metadata_latency_sum, r_end - r_start);
> +	percpu_counter_add(&m->metadata_latency_sum, lat);
> +	__update_min_latency(&m->metadata_latency_min, lat);
> +	__update_max_latency(&m->metadata_latency_max, lat);
>  }
>  #endif /* _FS_CEPH_MDS_METRIC_H */

Looks good overall though.

Note that this makes your stddev patches no longer merge cleanly.
They'll need to be rebased on top of this patch. Maybe send it
altogether as a series since there are dependencies here?

Thanks,
Xiubo Li March 17, 2020, 11:33 a.m. UTC | #2 
On 2020/3/17 19:12, Jeff Layton wrote:
> On Mon, 2020-03-16 at 20:00 -0400, xiubli@redhat.com wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> These will be very useful help diagnose problems.
>>
>> URL: https://tracker.ceph.com/issues/44533
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> ---
>>
>> Changed in V2:
>> - switch spin lock to cmpxchg
>>
>> Changed in V3:
>> - add the __update_min/max_latency helpers
>> - minor fix
>>
>>   fs/ceph/debugfs.c    | 26 +++++++++++++++++++++-----
>>   fs/ceph/mds_client.c |  9 +++++++++
>>   fs/ceph/metric.h     | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
>>   3 files changed, 79 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
>> index 60f3e307..bcf7215 100644
>> --- a/fs/ceph/debugfs.c
>> +++ b/fs/ceph/debugfs.c
>> @@ -130,27 +130,43 @@ static int metric_show(struct seq_file *s, void *p)
>>   	struct ceph_mds_client *mdsc = fsc->mdsc;
>>   	int i, nr_caps = 0;
>>   	s64 total, sum, avg = 0;
>> +	unsigned long min, max;
>>   
>> -	seq_printf(s, "item          total       sum_lat(us)     avg_lat(us)\n");
>> -	seq_printf(s, "-----------------------------------------------------\n");
>> +	seq_printf(s, "item          total       sum_lat(us)     avg_lat(us)     min_lat(us)     max_lat(us)\n");
>> +	seq_printf(s, "-------------------------------------------------------------------------------------\n");
>>   
>>   	total = percpu_counter_sum(&mdsc->metric.total_reads);
>>   	sum = percpu_counter_sum(&mdsc->metric.read_latency_sum);
>>   	sum = jiffies_to_usecs(sum);
>>   	avg = total ? sum / total : 0;
>> -	seq_printf(s, "%-14s%-12lld%-16lld%lld\n", "read", total, sum, avg);
>> +	min = atomic_long_read(&mdsc->metric.read_latency_min);
>> +	min = jiffies_to_usecs(min == ULONG_MAX ? 0 : min);
>> +	max = atomic_long_read(&mdsc->metric.read_latency_max);
>> +	max = jiffies_to_usecs(max);
>> +	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16ld%ld\n", "read",
>> +		   total, sum, avg, min, max);
>>   
>>   	total = percpu_counter_sum(&mdsc->metric.total_writes);
>>   	sum = percpu_counter_sum(&mdsc->metric.write_latency_sum);
>>   	sum = jiffies_to_usecs(sum);
>>   	avg = total ? sum / total : 0;
>> -	seq_printf(s, "%-14s%-12lld%-16lld%lld\n", "write", total, sum, avg);
>> +	min = atomic_long_read(&mdsc->metric.write_latency_min);
>> +	min = jiffies_to_usecs(min == ULONG_MAX ? 0 : min);
>> +	max = atomic_long_read(&mdsc->metric.write_latency_max);
>> +	max = jiffies_to_usecs(max);
>> +	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16ld%ld\n", "write",
>> +		   total, sum, avg, min, max);
>>   
>>   	total = percpu_counter_sum(&mdsc->metric.total_metadatas);
>>   	sum = percpu_counter_sum(&mdsc->metric.metadata_latency_sum);
>>   	sum = jiffies_to_usecs(sum);
>>   	avg = total ? sum / total : 0;
>> -	seq_printf(s, "%-14s%-12lld%-16lld%lld\n", "metadata", total, sum, avg);
>> +	min = atomic_long_read(&mdsc->metric.metadata_latency_min);
>> +	min = jiffies_to_usecs(min == ULONG_MAX ? 0 : min);
>> +	max = atomic_long_read(&mdsc->metric.metadata_latency_max);
>> +	max = jiffies_to_usecs(max);
>> +	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16ld%ld\n", "metadata",
>> +		   total, sum, avg, min, max);
>>   
>>   	seq_printf(s, "\n");
>>   	seq_printf(s, "item          total           miss            hit\n");
>> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
>> index 5c03ed3..7844aa6 100644
>> --- a/fs/ceph/mds_client.c
>> +++ b/fs/ceph/mds_client.c
>> @@ -4358,6 +4358,9 @@ static int ceph_mdsc_metric_init(struct ceph_client_metric *metric)
>>   	if (ret)
>>   		goto err_read_latency_sum;
>>   
>> +	atomic_long_set(&metric->read_latency_min, ULONG_MAX);
>> +	atomic_long_set(&metric->read_latency_max, 0);
>> +
>>   	ret = percpu_counter_init(&metric->total_writes, 0, GFP_KERNEL);
>>   	if (ret)
>>   		goto err_total_writes;
>> @@ -4366,6 +4369,9 @@ static int ceph_mdsc_metric_init(struct ceph_client_metric *metric)
>>   	if (ret)
>>   		goto err_write_latency_sum;
>>   
>> +	atomic_long_set(&metric->write_latency_min, ULONG_MAX);
>> +	atomic_long_set(&metric->write_latency_max, 0);
>> +
>>   	ret = percpu_counter_init(&metric->total_metadatas, 0, GFP_KERNEL);
>>   	if (ret)
>>   		goto err_total_metadatas;
>> @@ -4374,6 +4380,9 @@ static int ceph_mdsc_metric_init(struct ceph_client_metric *metric)
>>   	if (ret)
>>   		goto err_metadata_latency_sum;
>>   
>> +	atomic_long_set(&metric->metadata_latency_min, ULONG_MAX);
>> +	atomic_long_set(&metric->metadata_latency_max, 0);
>> +
>>   	return 0;
>>   
>>   err_metadata_latency_sum:
>> diff --git a/fs/ceph/metric.h b/fs/ceph/metric.h
>> index faba142..c9c76d5 100644
>> --- a/fs/ceph/metric.h
>> +++ b/fs/ceph/metric.h
>> @@ -2,6 +2,10 @@
>>   #ifndef _FS_CEPH_MDS_METRIC_H
>>   #define _FS_CEPH_MDS_METRIC_H
>>   
>> +#include <linux/atomic.h>
>> +#include <linux/percpu.h>
>> +#include <linux/spinlock.h>
>> +
>>   /* This is the global metrics */
>>   struct ceph_client_metric {
>>   	atomic64_t            total_dentries;
>> @@ -13,12 +17,18 @@ struct ceph_client_metric {
>>   
>>   	struct percpu_counter total_reads;
>>   	struct percpu_counter read_latency_sum;
>> +	atomic_long_t read_latency_min;
>> +	atomic_long_t read_latency_max;
>>   
>>   	struct percpu_counter total_writes;
>>   	struct percpu_counter write_latency_sum;
>> +	atomic_long_t write_latency_min;
>> +	atomic_long_t write_latency_max;
>>   
>>   	struct percpu_counter total_metadatas;
>>   	struct percpu_counter metadata_latency_sum;
>> +	atomic_long_t metadata_latency_min;
>> +	atomic_long_t metadata_latency_max;
>>   };
>>   
>>   static inline void ceph_update_cap_hit(struct ceph_client_metric *m)
>> @@ -31,16 +41,44 @@ static inline void ceph_update_cap_mis(struct ceph_client_metric *m)
>>   	percpu_counter_inc(&m->i_caps_mis);
>>   }
>>   
>> +static inline void __update_min_latency(atomic_long_t *min, unsigned long lat)
> nit: I don't see a need for the double-underscore prefix here.
>
>> +{
>> +	unsigned long cur, old;
>> +
>> +	cur = atomic_long_read(min);
>> +	do {
>> +		old = cur;
>> +		if (likely(lat >= old))
>> +			break;
>> +	} while ((cur = atomic_long_cmpxchg(min, old, lat)) != old);
>> +}
>> +
>> +static inline void __update_max_latency(atomic_long_t *max, unsigned long lat)
>> +{
>> +	unsigned long cur, old;
>> +
>> +	cur = atomic_long_read(max);
>> +	do {
>> +		old = cur;
>> +		if (likely(lat <= old))
>> +			break;
>> +	} while ((cur = atomic_long_cmpxchg(max, old, lat)) != old);
>> +}
>> +
>>   static inline void ceph_update_read_latency(struct ceph_client_metric *m,
>>   					    unsigned long r_start,
>>   					    unsigned long r_end,
>>   					    int rc)
>>   {
>> +	unsigned long lat = r_end - r_start;
>> +
>>   	if (rc < 0 && rc != -ENOENT && rc != -ETIMEDOUT)
>>   		return;
>>   
>>   	percpu_counter_inc(&m->total_reads);
>> -	percpu_counter_add(&m->read_latency_sum, r_end - r_start);
>> +	percpu_counter_add(&m->read_latency_sum, lat);
>> +	__update_min_latency(&m->read_latency_min, lat);
>> +	__update_max_latency(&m->read_latency_max, lat);
>>   }
>>   
>>   static inline void ceph_update_write_latency(struct ceph_client_metric *m,
>> @@ -48,11 +86,15 @@ static inline void ceph_update_write_latency(struct ceph_client_metric *m,
>>   					     unsigned long r_end,
>>   					     int rc)
>>   {
>> +	unsigned long lat = r_end - r_start;
>> +
>>   	if (rc && rc != -ETIMEDOUT)
>>   		return;
>>   
>>   	percpu_counter_inc(&m->total_writes);
>> -	percpu_counter_add(&m->write_latency_sum, r_end - r_start);
>> +	percpu_counter_add(&m->write_latency_sum, lat);
>> +	__update_min_latency(&m->write_latency_min, lat);
>> +	__update_max_latency(&m->write_latency_max, lat);
>>   }
>>   
>>   static inline void ceph_update_metadata_latency(struct ceph_client_metric *m,
>> @@ -60,10 +102,14 @@ static inline void ceph_update_metadata_latency(struct ceph_client_metric *m,
>>   						unsigned long r_end,
>>   						int rc)
>>   {
>> +	unsigned long lat = r_end - r_start;
>> +
>>   	if (rc && rc != -ENOENT)
>>   		return;
>>   
>>   	percpu_counter_inc(&m->total_metadatas);
>> -	percpu_counter_add(&m->metadata_latency_sum, r_end - r_start);
>> +	percpu_counter_add(&m->metadata_latency_sum, lat);
>> +	__update_min_latency(&m->metadata_latency_min, lat);
>> +	__update_max_latency(&m->metadata_latency_max, lat);
>>   }
>>   #endif /* _FS_CEPH_MDS_METRIC_H */
> Looks good overall though.
>
> Note that this makes your stddev patches no longer merge cleanly.
> They'll need to be rebased on top of this patch. Maybe send it
> altogether as a series since there are dependencies here?

Sure, will post the V4 later.

Thanks


> Thanks,
diff mbox series

Patch

diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
index 60f3e307..bcf7215 100644
--- a/fs/ceph/debugfs.c
+++ b/fs/ceph/debugfs.c
@@ -130,27 +130,43 @@  static int metric_show(struct seq_file *s, void *p)
 	struct ceph_mds_client *mdsc = fsc->mdsc;
 	int i, nr_caps = 0;
 	s64 total, sum, avg = 0;
+	unsigned long min, max;
 
-	seq_printf(s, "item          total       sum_lat(us)     avg_lat(us)\n");
-	seq_printf(s, "-----------------------------------------------------\n");
+	seq_printf(s, "item          total       sum_lat(us)     avg_lat(us)     min_lat(us)     max_lat(us)\n");
+	seq_printf(s, "-------------------------------------------------------------------------------------\n");
 
 	total = percpu_counter_sum(&mdsc->metric.total_reads);
 	sum = percpu_counter_sum(&mdsc->metric.read_latency_sum);
 	sum = jiffies_to_usecs(sum);
 	avg = total ? sum / total : 0;
-	seq_printf(s, "%-14s%-12lld%-16lld%lld\n", "read", total, sum, avg);
+	min = atomic_long_read(&mdsc->metric.read_latency_min);
+	min = jiffies_to_usecs(min == ULONG_MAX ? 0 : min);
+	max = atomic_long_read(&mdsc->metric.read_latency_max);
+	max = jiffies_to_usecs(max);
+	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16ld%ld\n", "read",
+		   total, sum, avg, min, max);
 
 	total = percpu_counter_sum(&mdsc->metric.total_writes);
 	sum = percpu_counter_sum(&mdsc->metric.write_latency_sum);
 	sum = jiffies_to_usecs(sum);
 	avg = total ? sum / total : 0;
-	seq_printf(s, "%-14s%-12lld%-16lld%lld\n", "write", total, sum, avg);
+	min = atomic_long_read(&mdsc->metric.write_latency_min);
+	min = jiffies_to_usecs(min == ULONG_MAX ? 0 : min);
+	max = atomic_long_read(&mdsc->metric.write_latency_max);
+	max = jiffies_to_usecs(max);
+	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16ld%ld\n", "write",
+		   total, sum, avg, min, max);
 
 	total = percpu_counter_sum(&mdsc->metric.total_metadatas);
 	sum = percpu_counter_sum(&mdsc->metric.metadata_latency_sum);
 	sum = jiffies_to_usecs(sum);
 	avg = total ? sum / total : 0;
-	seq_printf(s, "%-14s%-12lld%-16lld%lld\n", "metadata", total, sum, avg);
+	min = atomic_long_read(&mdsc->metric.metadata_latency_min);
+	min = jiffies_to_usecs(min == ULONG_MAX ? 0 : min);
+	max = atomic_long_read(&mdsc->metric.metadata_latency_max);
+	max = jiffies_to_usecs(max);
+	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16ld%ld\n", "metadata",
+		   total, sum, avg, min, max);
 
 	seq_printf(s, "\n");
 	seq_printf(s, "item          total           miss            hit\n");
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 5c03ed3..7844aa6 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -4358,6 +4358,9 @@  static int ceph_mdsc_metric_init(struct ceph_client_metric *metric)
 	if (ret)
 		goto err_read_latency_sum;
 
+	atomic_long_set(&metric->read_latency_min, ULONG_MAX);
+	atomic_long_set(&metric->read_latency_max, 0);
+
 	ret = percpu_counter_init(&metric->total_writes, 0, GFP_KERNEL);
 	if (ret)
 		goto err_total_writes;
@@ -4366,6 +4369,9 @@  static int ceph_mdsc_metric_init(struct ceph_client_metric *metric)
 	if (ret)
 		goto err_write_latency_sum;
 
+	atomic_long_set(&metric->write_latency_min, ULONG_MAX);
+	atomic_long_set(&metric->write_latency_max, 0);
+
 	ret = percpu_counter_init(&metric->total_metadatas, 0, GFP_KERNEL);
 	if (ret)
 		goto err_total_metadatas;
@@ -4374,6 +4380,9 @@  static int ceph_mdsc_metric_init(struct ceph_client_metric *metric)
 	if (ret)
 		goto err_metadata_latency_sum;
 
+	atomic_long_set(&metric->metadata_latency_min, ULONG_MAX);
+	atomic_long_set(&metric->metadata_latency_max, 0);
+
 	return 0;
 
 err_metadata_latency_sum:
diff --git a/fs/ceph/metric.h b/fs/ceph/metric.h
index faba142..c9c76d5 100644
--- a/fs/ceph/metric.h
+++ b/fs/ceph/metric.h
@@ -2,6 +2,10 @@ 
 #ifndef _FS_CEPH_MDS_METRIC_H
 #define _FS_CEPH_MDS_METRIC_H
 
+#include <linux/atomic.h>
+#include <linux/percpu.h>
+#include <linux/spinlock.h>
+
 /* This is the global metrics */
 struct ceph_client_metric {
 	atomic64_t            total_dentries;
@@ -13,12 +17,18 @@  struct ceph_client_metric {
 
 	struct percpu_counter total_reads;
 	struct percpu_counter read_latency_sum;
+	atomic_long_t read_latency_min;
+	atomic_long_t read_latency_max;
 
 	struct percpu_counter total_writes;
 	struct percpu_counter write_latency_sum;
+	atomic_long_t write_latency_min;
+	atomic_long_t write_latency_max;
 
 	struct percpu_counter total_metadatas;
 	struct percpu_counter metadata_latency_sum;
+	atomic_long_t metadata_latency_min;
+	atomic_long_t metadata_latency_max;
 };
 
 static inline void ceph_update_cap_hit(struct ceph_client_metric *m)
@@ -31,16 +41,44 @@  static inline void ceph_update_cap_mis(struct ceph_client_metric *m)
 	percpu_counter_inc(&m->i_caps_mis);
 }
 
+static inline void __update_min_latency(atomic_long_t *min, unsigned long lat)
+{
+	unsigned long cur, old;
+
+	cur = atomic_long_read(min);
+	do {
+		old = cur;
+		if (likely(lat >= old))
+			break;
+	} while ((cur = atomic_long_cmpxchg(min, old, lat)) != old);
+}
+
+static inline void __update_max_latency(atomic_long_t *max, unsigned long lat)
+{
+	unsigned long cur, old;
+
+	cur = atomic_long_read(max);
+	do {
+		old = cur;
+		if (likely(lat <= old))
+			break;
+	} while ((cur = atomic_long_cmpxchg(max, old, lat)) != old);
+}
+
 static inline void ceph_update_read_latency(struct ceph_client_metric *m,
 					    unsigned long r_start,
 					    unsigned long r_end,
 					    int rc)
 {
+	unsigned long lat = r_end - r_start;
+
 	if (rc < 0 && rc != -ENOENT && rc != -ETIMEDOUT)
 		return;
 
 	percpu_counter_inc(&m->total_reads);
-	percpu_counter_add(&m->read_latency_sum, r_end - r_start);
+	percpu_counter_add(&m->read_latency_sum, lat);
+	__update_min_latency(&m->read_latency_min, lat);
+	__update_max_latency(&m->read_latency_max, lat);
 }
 
 static inline void ceph_update_write_latency(struct ceph_client_metric *m,
@@ -48,11 +86,15 @@  static inline void ceph_update_write_latency(struct ceph_client_metric *m,
 					     unsigned long r_end,
 					     int rc)
 {
+	unsigned long lat = r_end - r_start;
+
 	if (rc && rc != -ETIMEDOUT)
 		return;
 
 	percpu_counter_inc(&m->total_writes);
-	percpu_counter_add(&m->write_latency_sum, r_end - r_start);
+	percpu_counter_add(&m->write_latency_sum, lat);
+	__update_min_latency(&m->write_latency_min, lat);
+	__update_max_latency(&m->write_latency_max, lat);
 }
 
 static inline void ceph_update_metadata_latency(struct ceph_client_metric *m,
@@ -60,10 +102,14 @@  static inline void ceph_update_metadata_latency(struct ceph_client_metric *m,
 						unsigned long r_end,
 						int rc)
 {
+	unsigned long lat = r_end - r_start;
+
 	if (rc && rc != -ENOENT)
 		return;
 
 	percpu_counter_inc(&m->total_metadatas);
-	percpu_counter_add(&m->metadata_latency_sum, r_end - r_start);
+	percpu_counter_add(&m->metadata_latency_sum, lat);
+	__update_min_latency(&m->metadata_latency_min, lat);
+	__update_max_latency(&m->metadata_latency_max, lat);
 }
 #endif /* _FS_CEPH_MDS_METRIC_H */