PerformanceTweaks [FreeBSD WIKI]

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====== Performance Tweaks ======

Email: <joseph.koshy@gmail.com>

This page contains a grab-bag of various performance-related tweaks for %%FreeBSD%%.  Once I collect enough material I'll write up something along the lines of a proper article.

===== LAN Performance =====
  * If your machines are on a fast, local (i.e., low-latency) network and large amounts of buffering need not indicate a high latency, try ''%%sysctl -w net.inet.tcp.inflight.enable=0%%'' (this is now default in -current for local links).

===== Mail =====
  * Setting ''%%"sysctl -w net.inet.tcp.delayed_ack=0"%%'' speeds up Cyrus IMAP and Postfix.   [[http://comments.gmane.org/gmane.mail.imap.cyrus/21299|Link]].

===== UFS Performance =====
  * If you're using UFS and have large directories, increasing the value of the ''%%vfs.ufs.dirhash_maxmem%%'' sysctl can deliver dramatic performace improvements by allowing UFS to cache the directory in kernel memory.  The default value is 2097152 (i.e., 2MB), and the ''%%vfs.ufs.dirhash_mem%%'' sysctl shows how much is currently being used.

===== Overall =====
  * If you're using 7.0-RELEASE, try running with ULE scheduler

====== External Links ======

  * [[http://silverwraith.com/papers/freebsd-tuning.php|Tuning FreeBSD for different applications]], by Avleen Vig.
  * [[http://lists.freebsd.org/pipermail/freebsd-performance/|FreeBSD-Performance Mailing List Archives]].

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