bumping MAXPHYS - success

[Wojciech Puchar]

bumped to 1024*1024=1MB in /usr/src/sys/sys/param.h and recompiled kernel.

all test performed on filesystem on which right newfs options were used so 
FFS were able to use it.

effects:

single process - almost no gain, bonnie++ showed about 5% worse speeds on 
linear read and linear write, about 2% better at rewrite, same with seek.

multiple process and heavy disk load - HUGE gain. copying large files does 
not slow down so much when doing
find / >/dev/null
in the same time, multiple large file operations performs smooth, much 
less seeks etc.


i will keep this setting.

tried to manipulate with vfs.{hi,lo}runningspace - defaults are OK, where 
hirunningspace=1MB=MAXPHYS. after enlarging performance was not better, 
while delays (average service time) much worse. so defaults are OK.

settings more than 1MB probably doesn't make sense.