(S)ATA performance in FBSD 6.2/7.0

[Divacky Roman]

On Fri, Mar 02, 2007 at 10:43:34AM +0100, Wojciech Puchar wrote:
> >another while the box didn't do anything else than copying. I watched the 
> >copy process via 'systat -vmstat 1' and realized, that the value of 'KB/t' 
> >never go byond 128 (128kb buffer limit?). But more frustrating, I never got
> 
> what's wrong? FreeBSD uses 128k limit by default.
> 
> edit /usr/src/sys/sys/param.h
> 
> and change
> 
> #define MAXPHYS         (128 * 1024)   /* max raw I/O transfer size */
> 
> 
> to say
> 
> #define MAXPHYS         (1024 * 1024)   /* max raw I/O transfer size */

did anyone measure impact on various benchmark of this change? is 128k the
optimal size for "nowadays computers" ? if we can squeeze more performance
out of a typical box by just raising one define it would be great...

roman