With FPM you can run several pools of processes with different setting.
     These are settings that can be tweaked per pool.
    
    
     
      - 
       listenstring
- 
       
        The address on which to accept FastCGI requests. Valid syntaxes are:
        'ip.add.re.ss:port', 'port', '/path/to/unix/socket'. This option is
        mandatory for each pool.
        
- 
       listen.backlogint
- 
       
        Set listen(2) backlog. A value of '-1' means unlimited. Default value:
        -1.
        
- 
       listen.allowed_clientsstring
- 
       
        List of IPv4 addresses of FastCGI clients which are allowed to
        connect. Equivalent to the FCGI_WEB_SERVER_ADDRS environment variable in the
        original PHP FastCGI (5.2.2+). Makes sense only with a tcp listening socket.
        Each address must be separated by a comma. If this value is left blank,
        connections will be accepted from any ip address. Default value: any.
        IPv6 addresses are allowed since PHP 5.5.20 and 5.6.4.
        
- 
       listen.ownerstring
- 
       
        Set permissions for unix socket, if one is used. In Linux, read/write
        permissions must be set in order to allow connections from a web
        server. Many BSD-derived systems allow connections regardless of permissions.
        Default values: user and group are set as the running user, mode is set to 0660.
        
- 
       listen.groupstring
- 
       
        See listen.owner.
        
- 
       listen.modestring
- 
       
        See listen.owner.
        
- 
       listen.acl_usersstring
- 
       
        When POSIX Access Control Lists are supported you can set them using this option.
        When set, listen.owner and listen.group
        are ignored. Value is a comma separated list of user names. Since PHP 5.6.5.
        
- 
       listen.acl_groupsstring
- 
       
        See listen.acl_users.
        Value is a comma separated list of group names. Since PHP 5.6.5.
        
- 
       userstring
- 
       
        Unix user of FPM processes. This option is mandatory.
        
- 
       groupstring
- 
       
        Unix group of FPM processes. If not set, the default user's group is
        used.
        
- 
       pmstring
- 
       
        Choose how the process manager will control the number of child
        processes. Possible values: static, ondemand,
        dynamic.
        This option is mandatory.
        
        static - the number of child processes is fixed (pm.max_children).
        
        ondemand - the processes spawn on demand (when requested,
        as opposed to dynamic, where pm.start_servers are started
        when the service is started.
        
        dynamic - the number of child processes is set dynamically based on the
        following directives: pm.max_children, pm.start_servers,
        pm.min_spare_servers, pm.max_spare_servers.
        
- 
       pm.max_childrenint
- 
       
        The number of child processes to be created when pm is set to
        static and the maximum number of child processes to be created
        when pm is set to dynamic. This
        option is mandatory.
        
        This option sets the limit on the number of simultaneous requests that
        will be served. Equivalent to the ApacheMaxClients directive with
        mpm_prefork and to the PHP_FCGI_CHILDREN environment variable in the
        original PHP FastCGI.
        
- 
       pm.start_serversint
- 
       
        The number of child processes created on startup.
        Used only when pm is set to dynamic.
        Default Value: min_spare_servers + (max_spare_servers -
        min_spare_servers) / 2.
        
- 
       pm.min_spare_serversint
- 
       
        The desired minimum number of idle server processes. Used only when
        pm is set to dynamic. Also
        mandatory in this case.
        
- 
       pm.max_spare_serversint
- 
       
        The desired maximum number of idle server processes. Used only when
        pm is set to dynamic. Also
        mandatory in this case.
        
- 
       pm.process_idle_timeoutmixed
- 
       
        The number of seconds after which an idle process will be killed. 
        Used only when pm is set to ondemand.
        Available units: s(econds)(default), m(inutes), h(ours), or d(ays).
        Default value: 10s.
        
- 
       pm.max_requestsint
- 
       
        The number of requests each child process should execute before
        respawning. This can be useful to work around memory leaks in 3rd party
        libraries. For endless request processing specify '0'. Equivalent to
        PHP_FCGI_MAX_REQUESTS. Default value: 0.
        
- 
       pm.status_pathstring
- 
       
        The URI to view the FPM status page. If this value is not set, no URI
        will be recognized as a status page. Default value: none.
        
- 
       ping.pathstring
- 
       
        The ping URI to call the monitoring page of FPM. If this value is not
        set, no URI will be recognized as a ping page. This could be used to test
        from outside that FPM is alive and responding. Please note that the value must
        start with a leading slash (/).
        
- 
       ping.responsestring
- 
       
        This directive may be used to customize the response to a ping
        request. The response is formatted as text/plain with a 200 response code.
        Default value: pong.
        
- 
       process.priorityint
- 
       
        Specify the nice(2) priority to apply to the worker process (only if set).
        The value can vary from -19 (highest priority) to 20 (lower priority).
        Default value: not set.
        
- 
       prefixstring
- 
       
        Specify prefix for path evaluation
        
- 
       request_terminate_timeoutmixed
- 
       
        The timeout for serving a single request after which the worker
        process will be killed. This option should be used when the 'max_execution_time'
        ini option does not stop script execution for some reason. A value of '0' means
        'Off'. Available units: s(econds)(default), m(inutes), h(ours), or d(ays).
        Default value: 0.
        
- 
       request_slowlog_timeoutmixed
- 
       
        The timeout for serving a single request after which a PHP backtrace
        will be dumped to the 'slowlog' file. A value of '0' means 'Off'.
        Available units: s(econds)(default), m(inutes), h(ours), or d(ays).
        Default value: 0.
        
- 
       slowlogstring
- 
       
        The log file for slow requests. Default value:
        #INSTALL_PREFIX#/log/php-fpm.log.slow.
        
- 
       rlimit_filesint
- 
       
        Set open file descriptor rlimit for child processes in this pool. Default value: system defined value.
        
- 
       rlimit_coreint
- 
       
        Set max core size rlimit for child processes in this pool. Possible Values: 'unlimited' or an integer greater or equal to 0.
        Default value: system defined value.
        
- 
       chrootstring
- 
       
        Chroot to this directory at the start. This value must be defined as
        an absolute path. When this value is not set, chroot is not used.
        
- 
       chdirstring
- 
       
        Chdir to this directory at the start. This value must be an absolute
        path. Default value: current directory or / when chroot.
        
- 
       catch_workers_outputboolean
- 
       
        Redirect worker stdout and stderr into main error log. If not set,
        stdout and stderr will be redirected to /dev/null according to FastCGI specs.
        Default value: no.
        
- 
       clear_envboolean
- 
       
        Clear environment in FPM workers.
        Prevents arbitrary environment variables from reaching FPM worker processes
        by clearing the environment in workers before env vars specified in this
        pool configuration are added. Since PHP 5.4.27, 5.5.11, and 5.6.0.
        Default value: Yes.
        
- 
       security.limit_extensionsstring
- 
       
        Limits the extensions of the main script FPM will allow to parse.
        This can prevent configuration mistakes on the web server side.
        You should only limit FPM to .php extensions to prevent malicious
        users to use other extensions to execute php code.
        Default value: .php .phar
        
- 
       access.logstring
- 
       
        The access log file.
        Default value: not set
        
- 
       access.formatstring
- 
       
        The access log format.
        Default value: "%R - %u %t \"%m %r\" %s"
        
     It's possible to pass additional environment variables and update PHP settings of a certain pool.
     To do this, you need to add the following options to the pool configuration file.