details: http://hg.nginx.org/nginx/rev/99770a5ea14f
branches:
changeset: 6828:99770a5ea14f
user: Ruslan Ermilov <ru@nginx.com>
date: Wed Dec 07 22:25:37 2016 +0300
description:
Slab: slots statistics.

For each slot, the number of total and used entries, as well as
the number of allocation requests and failures, are tracked.

diffstat:

src/core/ngx_slab.c | 57 ++++++++++++++++++++++++++++++++++++++++++----------
src/core/ngx_slab.h | 11 ++++++++++
2 files changed, 57 insertions(+), 11 deletions(-)

diffs (236 lines):

diff -r 0e61510c56c4 -r 99770a5ea14f src/core/ngx_slab.c
--- a/src/core/ngx_slab.c Wed Dec 07 22:25:37 2016 +0300
+++ b/src/core/ngx_slab.c Wed Dec 07 22:25:37 2016 +0300
@@ -120,7 +120,13 @@ ngx_slab_init(ngx_slab_pool_t *pool)
}

p += n * sizeof(ngx_slab_page_t);
- size -= n * sizeof(ngx_slab_page_t);
+
+ pool->stats = (ngx_slab_stat_t *) p;
+ ngx_memzero(pool->stats, n * sizeof(ngx_slab_stat_t));
+
+ p += n * sizeof(ngx_slab_stat_t);
+
+ size -= n * (sizeof(ngx_slab_page_t) + sizeof(ngx_slab_stat_t));

pages = (ngx_uint_t) (size / (ngx_pagesize + sizeof(ngx_slab_page_t)));

@@ -205,6 +211,8 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p
slot = 0;
}

+ pool->stats[slot].reqs++;
+
ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0,
"slab alloc: %uz slot: %ui", size, slot);

@@ -232,11 +240,13 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p

i = (n * sizeof(uintptr_t) * 8 + i) << shift;

+ p = (uintptr_t) bitmap + i;
+
+ pool->stats[slot].used++;
+
if (bitmap[n] == NGX_SLAB_BUSY) {
for (n = n + 1; n < map; n++) {
if (bitmap[n] != NGX_SLAB_BUSY) {
- p = (uintptr_t) bitmap + i;
-
goto done;
}
}
@@ -249,8 +259,6 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p
page->prev = NGX_SLAB_SMALL;
}

- p = (uintptr_t) bitmap + i;
-
goto done;
}
}
@@ -276,6 +284,8 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p

p = ngx_slab_page_addr(pool, page) + (i << shift);

+ pool->stats[slot].used++;
+
goto done;
}

@@ -305,6 +315,8 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p

p = ngx_slab_page_addr(pool, page) + (i << shift);

+ pool->stats[slot].used++;
+
goto done;
}
}
@@ -339,8 +351,12 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p

slots[slot].next = page;

+ pool->stats[slot].total += (ngx_pagesize >> shift) - n;
+
p = ngx_slab_page_addr(pool, page) + (n << shift);

+ pool->stats[slot].used++;
+
goto done;

} else if (shift == ngx_slab_exact_shift) {
@@ -351,8 +367,12 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p

slots[slot].next = page;

+ pool->stats[slot].total += sizeof(uintptr_t) * 8;
+
p = ngx_slab_page_addr(pool, page);

+ pool->stats[slot].used++;
+
goto done;

} else { /* shift > ngx_slab_exact_shift */
@@ -363,14 +383,20 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p

slots[slot].next = page;

+ pool->stats[slot].total += ngx_pagesize >> shift;
+
p = ngx_slab_page_addr(pool, page);

+ pool->stats[slot].used++;
+
goto done;
}
}

p = 0;

+ pool->stats[slot].fails++;
+
done:

ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0,
@@ -425,7 +451,7 @@ ngx_slab_free_locked(ngx_slab_pool_t *po
{
size_t size;
uintptr_t slab, m, *bitmap;
- ngx_uint_t n, type, slot, shift, map;
+ ngx_uint_t i, n, type, slot, shift, map;
ngx_slab_page_t *slots, *page;

ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab free: %p", p);
@@ -458,10 +484,10 @@ ngx_slab_free_locked(ngx_slab_pool_t *po
((uintptr_t) p & ~((uintptr_t) ngx_pagesize - 1));

if (bitmap[n] & m) {
+ slot = shift - pool->min_shift;

if (page->next == NULL) {
slots = ngx_slab_slots(pool);
- slot = shift - pool->min_shift;

page->next = slots[slot].next;
slots[slot].next = page;
@@ -484,14 +510,16 @@ ngx_slab_free_locked(ngx_slab_pool_t *po

map = (ngx_pagesize >> shift) / (sizeof(uintptr_t) * 8);

- for (n = 1; n < map; n++) {
- if (bitmap[n]) {
+ for (i = 1; i < map; i++) {
+ if (bitmap[i]) {
goto done;
}
}

ngx_slab_free_pages(pool, page, 1);

+ pool->stats[slot].total -= (ngx_pagesize >> shift) - n;
+
goto done;
}

@@ -508,9 +536,10 @@ ngx_slab_free_locked(ngx_slab_pool_t *po
}

if (slab & m) {
+ slot = ngx_slab_exact_shift - pool->min_shift;
+
if (slab == NGX_SLAB_BUSY) {
slots = ngx_slab_slots(pool);
- slot = ngx_slab_exact_shift - pool->min_shift;

page->next = slots[slot].next;
slots[slot].next = page;
@@ -527,6 +556,8 @@ ngx_slab_free_locked(ngx_slab_pool_t *po

ngx_slab_free_pages(pool, page, 1);

+ pool->stats[slot].total -= sizeof(uintptr_t) * 8;
+
goto done;
}

@@ -545,10 +576,10 @@ ngx_slab_free_locked(ngx_slab_pool_t *po
+ NGX_SLAB_MAP_SHIFT);

if (slab & m) {
+ slot = shift - pool->min_shift;

if (page->next == NULL) {
slots = ngx_slab_slots(pool);
- slot = shift - pool->min_shift;

page->next = slots[slot].next;
slots[slot].next = page;
@@ -565,6 +596,8 @@ ngx_slab_free_locked(ngx_slab_pool_t *po

ngx_slab_free_pages(pool, page, 1);

+ pool->stats[slot].total -= ngx_pagesize >> shift;
+
goto done;
}

@@ -604,6 +637,8 @@ ngx_slab_free_locked(ngx_slab_pool_t *po

done:

+ pool->stats[slot].used--;
+
ngx_slab_junk(p, size);

return;
diff -r 0e61510c56c4 -r 99770a5ea14f src/core/ngx_slab.h
--- a/src/core/ngx_slab.h Wed Dec 07 22:25:37 2016 +0300
+++ b/src/core/ngx_slab.h Wed Dec 07 22:25:37 2016 +0300
@@ -23,6 +23,15 @@ struct ngx_slab_page_s {


typedef struct {
+ ngx_uint_t total;
+ ngx_uint_t used;
+
+ ngx_uint_t reqs;
+ ngx_uint_t fails;
+} ngx_slab_stat_t;
+
+
+typedef struct {
ngx_shmtx_sh_t lock;

size_t min_size;
@@ -32,6 +41,8 @@ typedef struct {
ngx_slab_page_t *last;
ngx_slab_page_t free;

+ ngx_slab_stat_t *stats;
+
u_char *start;
u_char *end;

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