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Slab: slots statistics.
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For each slot, the number of total and used entries, as well as
the number of allocation requests and failures, are tracked.
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@mdocguard
mdocguard committed Dec 7, 2016
1 parent 366f131 commit 9ccf719
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Showing 2 changed files with 57 additions and 11 deletions.
57 changes: 46 additions & 11 deletions src/core/ngx_slab.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)));

Expand Down Expand Up @@ -205,6 +211,8 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)
slot = 0;
}

pool->stats[slot].reqs++;

ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0,
"slab alloc: %uz slot: %ui", size, slot);

Expand Down Expand Up @@ -232,11 +240,13 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)

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;
}
}
Expand All @@ -249,8 +259,6 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)
page->prev = NGX_SLAB_SMALL;
}

p = (uintptr_t) bitmap + i;

goto done;
}
}
Expand All @@ -276,6 +284,8 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)

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

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

goto done;
}

Expand Down Expand Up @@ -305,6 +315,8 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)

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

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

goto done;
}
}
Expand Down Expand Up @@ -339,8 +351,12 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)

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) {
Expand All @@ -351,8 +367,12 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)

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 */
Expand All @@ -363,14 +383,20 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)

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,
Expand Down Expand Up @@ -425,7 +451,7 @@ ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)
{
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);
Expand Down Expand Up @@ -458,10 +484,10 @@ ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)
((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;
Expand All @@ -484,14 +510,16 @@ ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)

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;
}

Expand All @@ -508,9 +536,10 @@ ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)
}

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;
Expand All @@ -527,6 +556,8 @@ ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)

ngx_slab_free_pages(pool, page, 1);

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

goto done;
}

Expand All @@ -545,10 +576,10 @@ ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)
+ 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;
Expand All @@ -565,6 +596,8 @@ ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)

ngx_slab_free_pages(pool, page, 1);

pool->stats[slot].total -= ngx_pagesize >> shift;

goto done;
}

Expand Down Expand Up @@ -604,6 +637,8 @@ ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)

done:

pool->stats[slot].used--;

ngx_slab_junk(p, size);

return;
Expand Down
11 changes: 11 additions & 0 deletions src/core/ngx_slab.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,15 @@ 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;

Expand All @@ -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;

Expand Down

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