Re: [PATCH 2/4] ceph: update the __update_latency helper

[Xiubo Li <xiubli@redhat.com>]

On 2021/3/23 20:34, Jeff Layton wrote:
> On Mon, 2021-03-22 at 20:28 +0800, xiubli@redhat.com wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> Let the __update_latency() helper choose the correcsponding members
>> according to the metric_type.
>>
>> URL: https://tracker.ceph.com/issues/49913
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> ---
>>   fs/ceph/metric.c | 58 +++++++++++++++++++++++++++++++++++-------------
>>   1 file changed, 42 insertions(+), 16 deletions(-)
>>
>> diff --git a/fs/ceph/metric.c b/fs/ceph/metric.c
>> index 75d309f2fb0c..d5560ff99a9d 100644
>> --- a/fs/ceph/metric.c
>> +++ b/fs/ceph/metric.c
>> @@ -249,19 +249,51 @@ void ceph_metric_destroy(struct ceph_client_metric *m)
>>   		ceph_put_mds_session(m->session);
>>   }
>>   
>>
>>
>>
>>
>>
>>
>>
>> -static inline void __update_latency(ktime_t *totalp, ktime_t *lsump,
>> -				    ktime_t *min, ktime_t *max,
>> -				    ktime_t *sq_sump, ktime_t lat)
>> +typedef enum {
>> +	CEPH_METRIC_READ,
>> +	CEPH_METRIC_WRITE,
>> +	CEPH_METRIC_METADATA,
>> +} metric_type;
>> +
>> +static inline void __update_latency(struct ceph_client_metric *m,
>> +				    metric_type type, ktime_t lat)
>>   {
>> +	ktime_t *totalp, *minp, *maxp, *lsump, *sq_sump;
>>   	ktime_t total, avg, sq, lsum;
>>   
>>
>>
>>
>>
>>
>>
>>
>> +	switch (type) {
>> +	case CEPH_METRIC_READ:
>> +		totalp = &m->total_reads;
>> +		lsump = &m->read_latency_sum;
>> +		minp = &m->read_latency_min;
>> +		maxp = &m->read_latency_max;
>> +		sq_sump = &m->read_latency_sq_sum;
>> +		break;
>> +	case CEPH_METRIC_WRITE:
>> +		totalp = &m->total_writes;
>> +		lsump = &m->write_latency_sum;
>> +		minp = &m->write_latency_min;
>> +		maxp = &m->write_latency_max;
>> +		sq_sump = &m->write_latency_sq_sum;
>> +		break;
>> +	case CEPH_METRIC_METADATA:
>> +		totalp = &m->total_metadatas;
>> +		lsump = &m->metadata_latency_sum;
>> +		minp = &m->metadata_latency_min;
>> +		maxp = &m->metadata_latency_max;
>> +		sq_sump = &m->metadata_latency_sq_sum;
>> +		break;
>> +	default:
>> +		return;
>> +	}
>> +
>>   	total = ++(*totalp);
> Why are you adding one to *totalp above? Is that to avoid it being 0?

No, in the old code we will count the 
total_reads/total_writes/total_metadatas for each call of the 
ceph_update_{read/write/metadata}_latency() helpers. And the same here.


>>   	lsum = (*lsump += lat);
>>   
>>
> ^^^
> Instead of doing all of the above with pointers, why not just add to
> total and lsum directly inside the switch statement? This seems like a
> lot of pointless indirection.

Okay, sounds good, will change it.


>>
>>
>>
>>
>> -	if (unlikely(lat < *min))
>> -		*min = lat;
>> -	if (unlikely(lat > *max))
>> -		*max = lat;
>> +	if (unlikely(lat < *minp))
>> +		*minp = lat;
>> +	if (unlikely(lat > *maxp))
>> +		*maxp = lat;
>>   
>>
>>
>>
>>   	if (unlikely(total == 1))
>>   		return;
>> @@ -284,9 +316,7 @@ void ceph_update_read_metrics(struct ceph_client_metric *m,
>>   		return;
>>   
>>
>>
>>
>>   	spin_lock(&m->read_metric_lock);
>> -	__update_latency(&m->total_reads, &m->read_latency_sum,
>> -			 &m->read_latency_min, &m->read_latency_max,
>> -			 &m->read_latency_sq_sum, lat);
>> +	__update_latency(m, CEPH_METRIC_READ, lat);
>>   	spin_unlock(&m->read_metric_lock);
>>   }
>>   
>>
>>
>>
>> @@ -300,9 +330,7 @@ void ceph_update_write_metrics(struct ceph_client_metric *m,
>>   		return;
>>   
>>
>>
>>
>>   	spin_lock(&m->write_metric_lock);
>> -	__update_latency(&m->total_writes, &m->write_latency_sum,
>> -			 &m->write_latency_min, &m->write_latency_max,
>> -			 &m->write_latency_sq_sum, lat);
>> +	__update_latency(m, CEPH_METRIC_WRITE, lat);
>>   	spin_unlock(&m->write_metric_lock);
>>   }
>>   
>>
>>
>>
>> @@ -316,8 +344,6 @@ void ceph_update_metadata_metrics(struct ceph_client_metric *m,
>>   		return;
>>   
>>
>>
>>
>>   	spin_lock(&m->metadata_metric_lock);
>> -	__update_latency(&m->total_metadatas, &m->metadata_latency_sum,
>> -			 &m->metadata_latency_min, &m->metadata_latency_max,
>> -			 &m->metadata_latency_sq_sum, lat);
>> +	__update_latency(m, CEPH_METRIC_METADATA, lat);
>>   	spin_unlock(&m->metadata_metric_lock);
>>   }