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Split "data_size" into "meta" and "data"
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Previously, the "data_size" field in the arcstats kstat contained the
amount of cached "metadata" and "data" in the ARC. The problem is this
then made it difficult to extract out just the "metadata" size, or just
the "data" size.

To make it easier to distinguish the two values, "data_size" has been
modified to count only buffers of type ARC_BUFC_DATA, and "meta_size"
was added to count only buffers of type ARC_BUFC_METADATA. If one wants
the old "data_size" value, simply sum the new "data_size" and
"meta_size" values.

Signed-off-by: Prakash Surya <[email protected]>
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Prakash Surya committed Feb 12, 2014
1 parent 513198f commit 520f372
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Showing 2 changed files with 25 additions and 14 deletions.
1 change: 1 addition & 0 deletions include/sys/arc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,7 @@ typedef enum arc_buf_contents {
*/
typedef enum arc_space_type {
ARC_SPACE_DATA,
ARC_SPACE_META,
ARC_SPACE_HDRS,
ARC_SPACE_L2HDRS,
ARC_SPACE_OTHER,
Expand Down
38 changes: 24 additions & 14 deletions module/zfs/arc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -308,6 +308,7 @@ typedef struct arc_stats {
kstat_named_t arcstat_size;
kstat_named_t arcstat_hdr_size;
kstat_named_t arcstat_data_size;
kstat_named_t arcstat_meta_size;
kstat_named_t arcstat_other_size;
kstat_named_t arcstat_anon_size;
kstat_named_t arcstat_anon_evict_data;
Expand Down Expand Up @@ -395,6 +396,7 @@ static arc_stats_t arc_stats = {
{ "size", KSTAT_DATA_UINT64 },
{ "hdr_size", KSTAT_DATA_UINT64 },
{ "data_size", KSTAT_DATA_UINT64 },
{ "meta_size", KSTAT_DATA_UINT64 },
{ "other_size", KSTAT_DATA_UINT64 },
{ "anon_size", KSTAT_DATA_UINT64 },
{ "anon_evict_data", KSTAT_DATA_UINT64 },
Expand Down Expand Up @@ -1367,6 +1369,9 @@ arc_space_consume(uint64_t space, arc_space_type_t type)
case ARC_SPACE_DATA:
ARCSTAT_INCR(arcstat_data_size, space);
break;
case ARC_SPACE_META:
ARCSTAT_INCR(arcstat_meta_size, space);
break;
case ARC_SPACE_OTHER:
ARCSTAT_INCR(arcstat_other_size, space);
break;
Expand All @@ -1378,7 +1383,9 @@ arc_space_consume(uint64_t space, arc_space_type_t type)
break;
}

ARCSTAT_INCR(arcstat_meta_used, space);
if (type != ARC_SPACE_DATA)
ARCSTAT_INCR(arcstat_meta_used, space);

atomic_add_64(&arc_size, space);
}

Expand All @@ -1393,6 +1400,9 @@ arc_space_return(uint64_t space, arc_space_type_t type)
case ARC_SPACE_DATA:
ARCSTAT_INCR(arcstat_data_size, -space);
break;
case ARC_SPACE_META:
ARCSTAT_INCR(arcstat_meta_size, -space);
break;
case ARC_SPACE_OTHER:
ARCSTAT_INCR(arcstat_other_size, -space);
break;
Expand All @@ -1404,10 +1414,13 @@ arc_space_return(uint64_t space, arc_space_type_t type)
break;
}

ASSERT(arc_meta_used >= space);
if (arc_meta_max < arc_meta_used)
arc_meta_max = arc_meta_used;
ARCSTAT_INCR(arcstat_meta_used, -space);
if (type != ARC_SPACE_DATA) {
ASSERT(arc_meta_used >= space);
if (arc_meta_max < arc_meta_used)
arc_meta_max = arc_meta_used;
ARCSTAT_INCR(arcstat_meta_used, -space);
}

ASSERT(arc_size >= space);
atomic_add_64(&arc_size, -space);
}
Expand Down Expand Up @@ -1604,12 +1617,11 @@ arc_buf_destroy(arc_buf_t *buf, boolean_t recycle, boolean_t all)
if (!recycle) {
if (type == ARC_BUFC_METADATA) {
arc_buf_data_free(buf, zio_buf_free);
arc_space_return(size, ARC_SPACE_DATA);
arc_space_return(size, ARC_SPACE_META);
} else {
ASSERT(type == ARC_BUFC_DATA);
arc_buf_data_free(buf, zio_data_buf_free);
ARCSTAT_INCR(arcstat_data_size, -size);
atomic_add_64(&arc_size, -size);
arc_space_return(size, ARC_SPACE_DATA);
}
}
if (list_link_active(&buf->b_hdr->b_arc_node)) {
Expand Down Expand Up @@ -2740,12 +2752,11 @@ arc_get_data_buf(arc_buf_t *buf)
if (!arc_evict_needed(type)) {
if (type == ARC_BUFC_METADATA) {
buf->b_data = zio_buf_alloc(size);
arc_space_consume(size, ARC_SPACE_DATA);
arc_space_consume(size, ARC_SPACE_META);
} else {
ASSERT(type == ARC_BUFC_DATA);
buf->b_data = zio_data_buf_alloc(size);
ARCSTAT_INCR(arcstat_data_size, size);
atomic_add_64(&arc_size, size);
arc_space_consume(size, ARC_SPACE_DATA);
}
goto out;
}
Expand Down Expand Up @@ -2790,7 +2801,7 @@ arc_get_data_buf(arc_buf_t *buf)
if ((buf->b_data = arc_evict(state, 0, size, recycle, evict)) == NULL) {
if (type == ARC_BUFC_METADATA) {
buf->b_data = zio_buf_alloc(size);
arc_space_consume(size, ARC_SPACE_DATA);
arc_space_consume(size, ARC_SPACE_META);

/*
* If we are unable to recycle an existing meta buffer
Expand All @@ -2805,8 +2816,7 @@ arc_get_data_buf(arc_buf_t *buf)
} else {
ASSERT(type == ARC_BUFC_DATA);
buf->b_data = zio_data_buf_alloc(size);
ARCSTAT_INCR(arcstat_data_size, size);
atomic_add_64(&arc_size, size);
arc_space_consume(size, ARC_SPACE_DATA);
}

/* Only bump this if we tried to recycle and failed */
Expand Down

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