Nginx Caching strategy
mdounin at mdounin.ru
Tue Oct 5 15:31:43 MSD 2010
On Mon, Oct 04, 2010 at 03:12:57PM -0400, cachenewbie wrote:
> All - Is there a high level tutorial on how nginx does caching ? Does
Some information is available here (in Russian):
Translation is available here (looks like correct one, but I
haven't really checked):
> it use mmap to map the cache directory/file into memory and share it
> with all nginx worker processes (and use sendfile to send it out to the
> socket) ? Or does it use directIO to open the file and use regular
> read/write syscalls ? This is for Linux debian platform.
nginx just saves responses to disk under the distinct names
(derived from cache key), with headers at start. When reading
from cache, nginx uses regular read() (or aio if available and
switched on) to read headers and normal file sending mecachnism to
"Normal file sending mechanism" implies sendfile, aio, directio
and so on - if available and configured.
Some metainformation about cache contents (to count cache
accesses, remove old files and so on) are stored in shared memory.
More information about the nginx