Commit b367de3d authored by Shuhei Matsumoto's avatar Shuhei Matsumoto Committed by Tomasz Zawadzki
Browse files

histogram: Rename bucket_shift by granularity throughout 



bucket shift basically defines the granularity of the histogram.
granularity will be better than bucket_shift to explain histogram
easily to users.

Change-Id: I368599cebdd155be6d2d9cfd944084e7c4964c98
Signed-off-by: default avatarShuhei Matsumoto <smatsumoto@nvidia.com>
Suggested-by: default avatarJim Harris <jim.harris@nvidia.com>
Reviewed-on: https://review.spdk.io/c/spdk/spdk/+/26000


Tested-by: default avatarSPDK Automated Test System <spdkbot@gmail.com>
Reviewed-by: default avatarJim Harris <jim.harris@nvidia.com>
parent 8f9167af

doc/jsonrpc.md

+4 −4
Original line number Diff line number Diff line
@@ -2856,7 +2856,7 @@ name | Required | string | Block device name 
Name                    | Description

------------------------| -----------

histogram               | Base64 encoded histogram

bucket_shift            | Granularity of the histogram buckets

granularity             | Granularity of the histogram buckets

tsc_rate                | Ticks per second



#### Example
@@ -2884,7 +2884,7 @@ Note that histogram field is trimmed, actual encoded histogram length is ~80kb. 
  "result": {

    "histogram": "AAAAAAAAAAAAAA...AAAAAAAAA==",

    "tsc_rate": 2300000000,

    "bucket_shift": 7

    "granularity": 7

  }

}

~~~
@@ -8254,7 +8254,7 @@ name | Required | string | Iscsi target node name 
Name                    | Description

------------------------| -----------

histogram               | Base64 encoded histogram

bucket_shift            | Granularity of the histogram buckets

granularity             | Granularity of the histogram buckets

tsc_rate                | Ticks per second



#### Example
@@ -8282,7 +8282,7 @@ Note that histogram field is trimmed, actual encoded histogram length is ~80kb. 
  "result": {

    "histogram": "AAAAAAAAAAAAAA...AAAAAAAAA==",

    "tsc_rate": 2300000000,

    "bucket_shift": 7

    "granularity": 7

  }

}

~~~

include/spdk/histogram_data.h

+15 −15
Original line number Diff line number Diff line
@@ -17,10 +17,10 @@ 
extern "C" {

#endif



#define SPDK_HISTOGRAM_BUCKET_SHIFT_DEFAULT	7

#define SPDK_HISTOGRAM_BUCKET_SHIFT(h)		h->bucket_shift

#define SPDK_HISTOGRAM_BUCKET_LSB(h)		(64 - SPDK_HISTOGRAM_BUCKET_SHIFT(h))

#define SPDK_HISTOGRAM_NUM_BUCKETS_PER_RANGE(h)	(1ULL << SPDK_HISTOGRAM_BUCKET_SHIFT(h))

#define SPDK_HISTOGRAM_GRANULARITY_DEFAULT	7

#define SPDK_HISTOGRAM_GRANULARITY(h)		h->granularity

#define SPDK_HISTOGRAM_BUCKET_LSB(h)		(64 - SPDK_HISTOGRAM_GRANULARITY(h))

#define SPDK_HISTOGRAM_NUM_BUCKETS_PER_RANGE(h)	(1ULL << SPDK_HISTOGRAM_GRANULARITY(h))

#define SPDK_HISTOGRAM_BUCKET_MASK(h)		(SPDK_HISTOGRAM_NUM_BUCKETS_PER_RANGE(h) - 1)

#define SPDK_HISTOGRAM_NUM_BUCKET_RANGES(h)	(SPDK_HISTOGRAM_BUCKET_LSB(h) + 1)

#define SPDK_HISTOGRAM_NUM_BUCKETS(h)		(SPDK_HISTOGRAM_NUM_BUCKETS_PER_RANGE(h) * \
@@ -52,13 +52,13 @@ extern "C" { 
 * On a 2.3GHz processor, this strategy results in 50ns buckets in the 7-14us range (sweet

 * spot for Intel Optane SSD latency testing).

 *

 * Buckets can be made more granular by increasing SPDK_HISTOGRAM_BUCKET_SHIFT.  This

 * Buckets can be made more granular by increasing SPDK_HISTOGRAM_GRANULARITY.  This

 * comes at the cost of additional storage per namespace context to store the bucket data.

 */



struct spdk_histogram_data {



	uint32_t	bucket_shift;

	uint32_t	granularity;

	uint64_t	*bucket;



};
@@ -68,20 +68,20 @@ __spdk_histogram_increment(struct spdk_histogram_data *h, uint32_t range, uint32 
{

	uint64_t *count;



	count = &h->bucket[(range << SPDK_HISTOGRAM_BUCKET_SHIFT(h)) + index];

	count = &h->bucket[(range << SPDK_HISTOGRAM_GRANULARITY(h)) + index];

	(*count)++;

}



static inline uint64_t

__spdk_histogram_get_count(const struct spdk_histogram_data *h, uint32_t range, uint32_t index)

{

	return h->bucket[(range << SPDK_HISTOGRAM_BUCKET_SHIFT(h)) + index];

	return h->bucket[(range << SPDK_HISTOGRAM_GRANULARITY(h)) + index];

}



static inline uint64_t *

__spdk_histogram_get_bucket(const struct spdk_histogram_data *h, uint32_t range, uint32_t index)

{

	return &h->bucket[(range << SPDK_HISTOGRAM_BUCKET_SHIFT(h)) + index];

	return &h->bucket[(range << SPDK_HISTOGRAM_GRANULARITY(h)) + index];

}



static inline void
@@ -138,7 +138,7 @@ __spdk_histogram_data_get_bucket_start(const struct spdk_histogram_data *h, uint 


	index += 1;

	if (range > 0) {

		bucket = 1ULL << (range + SPDK_HISTOGRAM_BUCKET_SHIFT(h) - 1);

		bucket = 1ULL << (range + SPDK_HISTOGRAM_GRANULARITY(h) - 1);

		bucket += (uint64_t)index << (range - 1);

	} else {

		bucket = index;
@@ -185,11 +185,11 @@ spdk_histogram_data_merge(const struct spdk_histogram_data *dst, 
{

	uint64_t i;



	/* Histograms with different bucket_shift values cannot be simply

	/* Histograms with different granularity values cannot be simply

	 * merged, because the buckets represent different ranges of

	 * values.

	 */

	if (dst->bucket_shift != src->bucket_shift) {

	if (dst->granularity != src->granularity) {

		return -EINVAL;

	}
@@ -201,7 +201,7 @@ spdk_histogram_data_merge(const struct spdk_histogram_data *dst, 
}



static inline struct spdk_histogram_data *

spdk_histogram_data_alloc_sized(uint32_t bucket_shift)

spdk_histogram_data_alloc_sized(uint32_t granularity)

{

	struct spdk_histogram_data *h;
@@ -210,7 +210,7 @@ spdk_histogram_data_alloc_sized(uint32_t bucket_shift) 
		return NULL;

	}



	h->bucket_shift = bucket_shift;

	h->granularity = granularity;

	h->bucket = (uint64_t *)calloc(SPDK_HISTOGRAM_NUM_BUCKETS(h), sizeof(uint64_t));

	if (h->bucket == NULL) {

		free(h);
@@ -223,7 +223,7 @@ spdk_histogram_data_alloc_sized(uint32_t bucket_shift) 
static inline struct spdk_histogram_data *

spdk_histogram_data_alloc(void)

{

	return spdk_histogram_data_alloc_sized(SPDK_HISTOGRAM_BUCKET_SHIFT_DEFAULT);

	return spdk_histogram_data_alloc_sized(SPDK_HISTOGRAM_GRANULARITY_DEFAULT);

}



static inline void

lib/bdev/bdev_rpc.c

+1 −1
Original line number Diff line number Diff line
@@ -1119,7 +1119,7 @@ _rpc_bdev_histogram_data_cb(void *cb_arg, int status, struct spdk_histogram_data 
	w = spdk_jsonrpc_begin_result(request);

	spdk_json_write_object_begin(w);

	spdk_json_write_named_string(w, "histogram", encoded_histogram);

	spdk_json_write_named_int64(w, "bucket_shift", histogram->bucket_shift);

	spdk_json_write_named_int64(w, "granularity", histogram->granularity);

	spdk_json_write_named_int64(w, "tsc_rate", spdk_get_ticks_hz());

	spdk_json_write_object_end(w);

	spdk_jsonrpc_end_result(request, w);

lib/iscsi/iscsi_rpc.c

+1 −1
Original line number Diff line number Diff line
@@ -1987,7 +1987,7 @@ rpc_iscsi_get_histogram(struct spdk_jsonrpc_request *request, 


	spdk_json_write_object_begin(w);

	spdk_json_write_named_string(w, "histogram", encoded_histogram);

	spdk_json_write_named_int64(w, "bucket_shift", target->histogram->bucket_shift);

	spdk_json_write_named_int64(w, "granularity", target->histogram->granularity);

	spdk_json_write_named_int64(w, "tsc_rate", spdk_get_ticks_hz());



	spdk_json_write_object_end(w);

scripts/histogram.py

+8 −8
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ import struct 
buf = sys.stdin.readlines()

json = json.loads(" ".join(buf))

histogram = base64.b64decode(json["histogram"])

bucket_shift = json["bucket_shift"]

granularity = json["granularity"]

tsc_rate = json["tsc_rate"]



print("Latency histogram")
@@ -23,20 +23,20 @@ so_far = 0 
bucket = 0

total = 1



for i in range(0, 64 - bucket_shift):

    for j in range(0, (1 << bucket_shift)):

        index = (((i << bucket_shift) + j) * 8)

for i in range(0, 64 - granularity):

    for j in range(0, (1 << granularity)):

        index = (((i << granularity) + j) * 8)

        total += int.from_bytes(histogram[index:index + 8], 'little')



for i in range(0, 64 - bucket_shift):

    for j in range(0, (1 << bucket_shift)):

        index = (((i << bucket_shift) + j)*8)

for i in range(0, 64 - granularity):

    for j in range(0, (1 << granularity)):

        index = (((i << granularity) + j)*8)

        count = int.from_bytes(histogram[index:index + 8], 'little')

        so_far += count

        last_bucket = bucket



        if i > 0:

            bucket = (1 << (i + bucket_shift - 1))

            bucket = (1 << (i + granularity - 1))

            bucket += ((j+1) << (i - 1))

        else:

            bucket = j+1