AFPA Directives: IBM HTTP Server
System Administration IBM HTTP Server documentation
Applies to Windows NT Applies to AIX

AFPA Directives


Applies to Windows NT  

AfpaAdvancedTuning

  • Syntax - AfpaAdvancedTuning tuning_string
  • Scope - One per physical Apache server
  • Default - None
  • Notes -
    • Valid on Windows NT only.
    • The AFPA directives control the Fast Response Cache Accelerator function.

The AfpaAdvancedTuning directive has advanced tuning parameters that require an extensive understanding of Web server performance issues. Using these switches incorrectly could lead to system instability and poor performance. The default settings are considered the optimal settings for the most demanding scenarios. The default settings are aggressive.

Brief description of switches and their defaults:

  • /bufs - Number of logging buffers (each log buf is 65536; all log buffers are written every 5 seconds), default = 285
  • /size - Maximum cached file size, default = 92160
  • /conns - Number of connection endpoints, default = 6500
  • /ttl - Time in seconds items are kept hot, default = 180
  • /threads - Number of worker threads per CPU, default = 3
  • /active - Maximum worker threads active per CPU, default = 10

Long description of switches:

  • The "/bufs" switch specifies the number of logging buffers used by AFPA, for access logging. The buffers are necessary to store access logs until they are written to disk. AFPA writes all log buffers to disk every 5 seconds. The higher the throughput, the more memory required to store log entries. The number of buffers required is roughly equal to (tps*ls*5)/65536, where "tps" is the expected transactions per second and "Ls" is the typical size data necessary to log the transaction. Assuming log entries are no more than 256 bytes and the number of logging buffers is 285 (the default), AFPA could process 14592 transactions per second, without requiring more log buffers.
  • The "/size" switch specifies the maximum size of files AFPA keeps in its primary cache. Files larger than this size are cached in the AFPA secondary cache. The primary cache is backed by pinned memory.
  • The "/conns" switch specifies the number of preallocated sockets used by AFPA. AFPA pre-allocates sockets for performance reasons. Choose the number of pre-allocated sockets to approximate the expected transactions per second.
  • The "/ttl" switch specifies in seconds the maximum lifetime (time to live) of a file in the AFPA primary cache. When this time elapses, the file is removed from the AFPA primary cache. Setting this value to zero prevents AFPA from aging files from the primary cache.
  • The "/threads" switch specifies the number of worker threads used by AFPA to process requests.
  • The "/active" switch specifies the number of worker threads concurrently active and not blocked on I/O.

Example of Optimized Settings for typical 1, 2, and 4-way machines

  • 1-way: AfpaAdvanced Tuning "/bufs 68 /size 75000 /conn 8000"
  • 2-way: AfpaAdvancedTuning "/bufs 93 /size 75000 /conn 10000"
  • 4-way: AfpaAdvancedTuning "/bufs 123 /size 65000 /conn 12000"
Applies to AIX  

AfpaBindLogger

  • Description - AfpaBindLogger [-1,0,1,..,n]
  • Scope - One per physical Apache server
  • Default - (-1)
  • Notes -
    • Valid on AIX only.
    • The AFPA directives control the Fast Response Cache Accelerator function.
    • This command only binds the kernel logging thread to a processor.

AfpaBindLogger allows you to bind the Fast Response Cache logging thread in the kernel to a specific processor. The format of the command is AfpaBindLogger [-1, 0, 1, ..., n], where -1 leaves the logging thread unbound and a number from 0 to total number of processors on the system, binds the logging thread to that processor.

Applies to AIX Applies to Windows NT  

AfpaCache

  • Description - Turns Fast Response Cache Accelerator on or off
  • Scope - Server configuration, virtual host, directory, per-directory configuration file
  • Syntax - On or off
  • Usage - AfpaCache on
  • Default - None
  • Override - Options
  • Multiple instances in the configuration file - Allowed
  • Notes -
    • Valid on AIX and Windows NT.
    • The AFPA directives control the Fast Response Cache Accelerator function.

The AfpaCache directive turns the Fast Response Cache Accelerator on or off for a particular scope (such as a directory). This directive applies to all descendants in a scope, unless otherwise modified by another directive.

 
Applies to AIX Applies to Windows NT  

AfpaEnable

  • Syntax - AfpaEnable
  • Description - Enables Fast Response Cache Accelerator
  • Scope - One per physical Apache server
  • Default - Fast Response Cache Accelerator disabled
  • Notes -
    • Valid on AIX and Windows NT.
    • The AFPA directives control the Fast Response Cache Accelerator function.

The AfpaEnable directive enables the Fast Response Cache Accelerator (Cache Accelerator). If the directive is present, the Cache Accelerator listens on either the TCP port specified by the Port directive, or the default port (80). The Cache Accelerator listens on the ports of all active TCP/IP adapters on the server. If the port is bound to a particular TCP/IP adapter, the Cache Accelerator is disabled.

Applies to AIX Applies to Windows NT  

AfpaLogFile

  • Description - Defines the Cache Accelerator log file name, location, and logging format
  • Scope - One entry per physical Apache server
  • Values - file_path_and_name log_format
  • Default - /tmp/afpa.logb
  • Log Formats -
    • CLF = Common Log Format
    • ECLF = Extended Common Log Format
    • V-CLF = Common Log Format with virtual host information
    • V-ECLF = Extended Common Log Format with virtual host information
    • BINARY = Binary log with virtual host information (AIX only)
  • Multiple instances in the config file - Not allowed
  • Notes -
    • Valid on AIX and Windows NT.
    • The AFPA directives control the Fast Response Cache Accelerator function.

Defaults to Cache Accelerator logging disabled, if AfpaLogFile directive is not present.

The current date is used as the filetype for the log file. The log file is automatically rolled over at midnight each day.

Applies to AIX  

AfpaLogging

  • Description - AfpaLogging on or off
  • Scope - One per physical Apache server
  • Values - On or off
  • Default - (-1)
  • Notes -
    • Valid on AIX only.
    • The AFPA directives control the Fast Response Cache Accelerator function.

The AfpaLogging directive turns the Fast Response Cache Accelerator logging on or off.

Applies to AIX  

AfpaMaxCache

  • Syntax - AfpaMaxCache [size]
  • Scope - One per physical Apache Server
  • Default - None
  • Notes -
    • Valid on AIX only.
    • The AFPA directives control the Fast Response Cache Accelerator function.

The AfpaMaxCache directive specifies the maximum file size inserted into the Fast Response Cache Accelerator cache.

Applies to AIX  

AfpaMinCache

  • Syntax - AfpaMinCache [size]
  • Scope - One per physical Apache server
  • Default - None
  • Notes -
    • Valid on AIX only.
    • The AFPA directives control the Fast Response Cache Accelerator function.

The AfpaMinCache directive specifies the minimum file size inserted into the Fast Response Cache Accelerator cache.

Applies to AIX  

AfpaRevalidationTimeout

  • Syntax - AfpaRevalidationTimeout <seconds>
  • Scope - Global
  • Default - 60
  • Notes -
    • Valid on AIX only.
    • The AFPA directives control the Fast Response Cache Accelerator function.

AfpaRevalidationTimeout sets the time interval for revalidation of a cached object. Once an object is cached in the kernel after the time interval has expired, the kernel forces the next request of the object to set up the Apache Server for revalidation. The time interval is expressed in seconds.

Applies to AIX  

AfpaSendServerHeader

  • Syntax - AfpaSendServerHeader true or false
  • Scope - One per physical Apache Server
  • Default - True
  • Notes -
    • Valid on AIX only.
    • The AFPA directives control the Fast Response Cache Accelerator function.

The AfpaSendServerHeader directive specifies whether or not the Fast Response Cache Accelerator sends the HTTP Server header in the response.

 
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