ngx_slab_stat

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2023-12-01

ngx_slab_stat

This module provides access to information of slab usage for nginx/tengine shared memory.

Example

Get information of slab and free page usage.

http {
   server {
       listen 80;

       location = /slab_stat {
           slab_stat;
       }
   }
}

Requesting URI /slab_stat, you will get information of slab and free page usage for nginx/tengine shared memory. The output page may look like as follows:

$ curl http://localhost:80/slab_stat
* shared memory: one
total:      102400(KB) free:      101792(KB) size:           4(KB)
pages:      101792(KB) start:0000000003496000 end:0000000009800000
slot:           8(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:          16(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:          32(Bytes) total:         127 used:           1 reqs:           1 fails:           0
slot:          64(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:         128(Bytes) total:          32 used:           1 reqs:           1 fails:           0
slot:         256(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:         512(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:        1024(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:        2048(Bytes) total:           0 used:           0 reqs:           0 fails:           0

Get information of shared memory usage

Data

Every line except the first three of output content has the same format, as follows:

shared memory: name of current shared memory zone
total: total size of current shared memory zone
free: free size of current shared memory zone now
size: page size of current shared memory zone
pages: continuous page size that can be allocated
start: start address of current continuous page size
end: end address of current continuous page size
slot: slot that can be allocated
total: total number of current slot
used: used number of current slot
reqs: reqs number of current slot
fails: fails number of current slot

Nginx Compatibility

The latest module is compatible with the following versions of nginx:

1.13.4 (stable version of 1.13.x)

Nginx cores older than 1.13.x should be patched (refer "Install").

Tengine Compatibility

2.1.1 (stable version of 2.1.x)

Tengine version older than 2.1.x should be patched (refer "Install").

Install

Install this module from source:

$ wget http://nginx.org/download/nginx-1.13.4.tar.gz
$ tar -xzvf nginx-1.13.4.tar.gz
$ cd nginx-1.13.4/
$ ./configure --add-module=/path/to/ngx_slab_stat
$ make -j4 && make install

Note that slab_stat.patch should be applied when nginx cores older than 1.13.x, you can also generate this patch by diff with nginx 1.13.x.

$ patch -p1 < /path/to/ngx_slab_stat/slab_stat.patch

Directive

Syntax: slab_stat

Default: none

Context: server, location

The information of nginx shared memory usage will be accessible from the surrounding location.

Exception

Now only support shared memory allocated from nginx and lua-nginx-module