ngx_slab_stat

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