[linux-cifs-client] directio cifs more than doubled loopback file copy (write) perf

[Steve French]

On Thu, 2004-12-02 at 13:20, Steve French wrote:
> As expected even larger writes do help - a lot. See below:
> 
> 4K writes through page cache - 			1.3  seconds 38MB/sec
> (4K writes direct are about the same as above)
> 
> 16K writes (mount -o direct)			0.5 sec	    100MB/sec seconds	100MB/sec
> 
> 60K writes (change #define CIFS_MAX_MSGSIZE	0.35 sec    143MB/sec
>      on client and add "max xmit = 62000 in
>      smb.conf on the server, and mount direct)
> 
> I can probably do a lot better than that.  Also note that this is just a
> laptop, not a high end server, and that the amount of data copied would
> fit in is small and likely is fitting in the (server) page cache without
> JFS having to hit the disk much (larger sizes would hit the disk a lot
> more obviously).
> 
> I suspect that direct i/o will help a lot with client memory pressure as
> well since less inode data caching will be going on. 
> 

The local JFS numbers, for comparison are 0.113 seconds ie 442MB/sec