Re: rc80211-pid: some tuning test results

[Stefano Brivio <stefano.brivio@polimi.it>]

I run further tests. It looks like I found out the optimal parameters for
minimizing latency or maximizing throughput or maximizing reliability.

Best throughput:
rc_imul rc_idiv rc_pf   rc_p    rc_i    rc_d    rc_sm_s rc_sh_s rc_sh_d
1       8        11     14       10     12       3      0        1

Best latency:
rc_imul rc_idiv rc_pf   rc_p    rc_i    rc_d    rc_sm_s rc_sh_s rc_sh_d
1       8        15     12       8      16       2      1        1

Best reliability:
rc_imul rc_idiv rc_pf   rc_p    rc_i    rc_d    rc_sm_s rc_sh_s rc_sh_d
1       8        4      15       8      15       3      0        0

While a general good setup looks to be:

rc_imul rc_idiv rc_pf   rc_p    rc_i    rc_d    rc_sm_s rc_sh_s rc_sh_d
1       8        10     15       9      15       3      0        1

I would then adopt a system like the one outlined below in order to take
into account userspace parameters.

We have Three userspace parameters, ranging from 0 (don't care) to 5
(care the most). I don't think it makes any sense to have more granularity
here.

Starting from:
rc_imul rc_idiv rc_pf   rc_p    rc_i    rc_d    rc_sm_s rc_sh_s rc_sh_d
1       8        10     15       9      15       3      0        1

We add:
For every threshold point:
rc_imul rc_idiv rc_pf   rc_p    rc_i    rc_d    rc_sm_s rc_sh_s rc_sh_d
		+0.2	-0.2	+0.2	-0.6

latency points:
rc_imul rc_idiv rc_pf   rc_p    rc_i    rc_d    rc_sm_s rc_sh_s rc_sh_d
		+1	-0.6	-0.2	+0.2	-0.2	+0.2

reliability points:
rc_imul rc_idiv rc_pf   rc_p    rc_i    rc_d    rc_sm_s rc_sh_s rc_sh_d
		-1.2		-0.2				-0.2

I'll now try to implement this sorting out the fixed point calculation
issues.


--
Ciao
Stefano