[ros-kernel] Re: Filesystem cache

[Hartmut B. <har...@te...>]

> -----Ursprungliche Nachricht-----
> Von:	Phillip Susi [SMTP:ps...@cf...]
> Gesendet am:	Sonntag, 30. September 2001 16:47
> An:	ros...@re...
> Betreff:	[ros-kernel] Re:  Filesystem cache
> 
> I'm not sure, but I think that sometimes the directory data is cached, such 
> as when opening files or changing directories, it does not seem to read the 
> disk, but when doing a simple dir command, there is intense disk IO and 
> each file in the directory is printed one at a time, very slowly, as if it 
> were still reading in a sector from the disk for each file found in the 
> directory.

I've made some test with the original vfat driver, with caching 
enabled but without direct access to the cache segments and 
with direct access to the cache segments. There is no difference 
between this three drivers (<15sec), when I try a 'dir /s' from 
cmd.exe. The partition has a size of 500MB with 7500 files in 
1500 directories. The time for the dir command is 6min 
(AMD486 with 100MHz). When I start the 'dir /s' command 
and than switch to an other console with ALT+TAB, the time is 
redused to 3 min?! The slowly output comes from the console output. 
The intense disk IO (without caching) is problem from cmd.exe. 
With the '/s', each directory is scaned for two times, 
the first to read the subdirs and the second to read and print 
out the files and subdirs.  

- Hartmut

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