Re: Increasing MAXPHYS

Ivan Voras wrote:
> Julian Elischer wrote:
>> You can get better throughput by using TSC for timing because the geom
>> and devstat code does a bit of timing.. Geom can be told to turn off
>> it's timing but devstat can't. The 170 ktps is with TSC as timer,
>> and geom timing turned off.
> 
> I see. I just ran randomio on a gzero device and with 10 userland
> threads (this is a slow 2xquad machine) I get g_up and g_down saturated
> fast with ~~ 120 ktps. Randomio uses gettimeofday() for measurements.

I've just got 140Ktps from two real Intel X25-M SSDs on ICH10R AHCI
controller and single Core2Quad CPU. So at least on synthetic tests it
is potentially reachable even with casual hardware, while it completely
saturated quad-core CPU.

> Hmm, it looks like it could be easy to spawn more g_* threads (and,
> barring specific class behaviour, it has a fair chance of working out of
> the box) but the incoming queue will need to also be broken up for
> greater effect.

According to "notes", looks there is a good chance to obtain races, as
some places expect only one up and one down thread.

-- 
Alexander Motin