with WriteFIleGather, the disk is always keep busy without entering and leaving from kernel mode. log data can be written to disk at a rate that approaches the limits of the physical characteristics of the hardware device.that’s really boost the I/O performance.

because the CPU is mostly idle during write operation,to maximum the performance,I have compressed the data before writing to the disk to reduce the amount of data to be written,the compress is always faster than the I/O operation,so that I get the compression for “free”.

after these changes,the performance for logging system has increased by over 43%.

Once FastCgi is installed,Config FastCGI extension to work with php:

1. Open a command line window,and change the current directory  to %WINDIR%\system32\inetsrv.
2. Run
   cscript fcgiconfig.js -add -section:"PHP" -extension:php -path:"C:\PHP\php-cgi.exe"
   to register the PHP CGI program as the one that will be processing .php extensions.
3. Modify fcigext.ini file in %WINDIR%\system32\inetsrv as the following (assuming you installed PHP to C:\PHP folder):
   

   [Types]
   php=PHP

   [PHP]
   ExePath=c:\php\php-cgi.exe

Next,download and install eAccelerator.eAccelerator is a free open-source PHP accelerator, optimizer, and dynamic content cache. It increases the performance of PHP scripts by caching them in their compiled state, so that the overhead of compiling is almost completely eliminated. It also optimizes scripts to speed up their execution. eAccelerator typically reduces server load and increases the speed of your PHP code by 1-10 times.

After eAccelerator is downloaded:

1. Copy eaccelerator.dll to your php extensions folder to c:\php\extensions.(assuming you installed PHP to C:\PHP folder)
2. Create a folder (with the appropriate permissions) for the temporary cached files.
   For example: c:\tmp\eaccelerator
3. Add the following to your php.ini (as the first loaded extension):
   

   extension=eAccelerator.dll
   eaccelerator.shm_size="128"
   eaccelerator.cache_dir="c:\tmp\eaccelerator"
   eaccelerator.enable="1"
   eaccelerator.optimizer="1"
   eaccelerator.check_mtime="1"
   eaccelerator.filter=""
   eaccelerator.shm_max="0"
   eaccelerator.shm_ttl="0"
   eaccelerator.shm_prune_period="0" 
   eaccelerator.shm_only="0"
   eaccelerator.compress="1"
   eaccelerator.compress_level="9"
   eaccelerator.keys = "shm"
   eaccelerator.sessions = "shm"
   eaccelerator.content = "shm"

That’s all,restart your IIS and you’ll get a faster Wordpress on windows IIS 6 with highly boosted performance.

Because IIS does not support mod_rewrite module for rewriting URLs,the biggest problem hosting wordpress on iis is that you always get an ‘ugly’ and not SEO-friendly index.php in your permalinks.you can install wp_url_rewriting,an open source URL rewriting for wordpress, to resolve this issue.

关于冲突检测的两种方式的对比(chaining and open addressing)：

http://www.absoluteastronomy.com/enc1/hash_table

Google有一个高效的实现Open addressing hash 的开源项目

http://goog-sparsehash.sourceforge.net/

Open addressing的性能可能会更好些，但是前提是需要一个非常好的hash生成算法。如果使用Chaining方式，加上一个非常高效的memory pool管理，减少cache失效时间，平均性能应该和Open addressing差不多。

顺便了解下judy:
A Performance Comparison of Judy to Hash Tables