Hard disk bottle neck.

Wojciech Puchar wojtek at wojtek.tensor.gdynia.pl
Sun Sep 28 15:00:05 UTC 2008

> the following code:
> patch /usr/src/sys/sys/param.h
> #ifndef DFLTPHYS
> #define DFLTPHYS        (1024 * 1024)   /* default max raw I/O transfer size
> */
> #endif
> #ifndef MAXPHYS
> #define MAXPHYS         (1024 * 1024)   /* max raw I/O transfer size */
> #endif
> #ifndef MAXDUMPPGS
> I'll update the result. I'll tell you how I go. Maybe sometimes in the next
> fortnight.
> Thanks everyone, thanks Wojciech Puchar,

after you recompile the kernel with that patch, check your disk 
performance in some directory consisting of many large files

cd that_dir
for x in *;do (cat $x >/dev/null &);done

while running systat,:vmstat on another console

i've just did this on one of my systems, with ONE 500GB SATA drive and 
with geli encryption.

got 48MB/s and about 50% CPU load with core2 duo.

More information about the freebsd-questions mailing list