directio question

Stefan Parvu sparvu at
Sun Mar 7 21:07:13 MSK 2010


My name is Stefan Parvu, Im working on
and I have started to test and consider replacing for our solution 
apache over nginx. Im getting to know nginx and I like the server.

Some question reading over
about DirectIO:

"The directive enables use of flags O_DIRECT (FreeBSD, Linux), 
F_NOCACHE (Mac OS X) or directio() function (Solaris) for reading 
files with size greater than specified. This directive disables 
use of sendfile for this request." 

DirectIO in Solaris is a feature, when enabled lets you to bypass entirely the
OS's page cache and read/write directly from/to disk. This has some
benefits where workloads are database servers and you want to avoid
double caching. 

Im a bit curious under what situations would like to have DirectIO enabled on
nginx and are we talking about same thing when we refer to directio ?

Usually most applications will benefit of having the OS's page cache involved 
rather of going to disk. 


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