Re: Power saving features for iwl4965

[Pedro Francisco <pedrogfrancisco@gmail.com>]

On Mon, Jun 3, 2013 at 3:18 PM, Stanislaw Gruszka <sgruszka@redhat.com> wrote:
> On Mon, Jun 03, 2013 at 10:52:39AM +0200, Tino Keitel wrote:
>> On Mon, Jan 07, 2013 at 12:08:00 +0100, Stanislaw Gruszka wrote:
>>
>> [...]
>>
>> > I posted patch here
>> > http://marc.info/?l=linux-wireless&m=135601033021616&w=2
>> >
>> > But I did not review code regarding power save to catch possible
>> > problems. Testing are bug reporting are welcome ...
>>
>> Hi,
>>
>> the patch is surprisingly small. To me it looks like it only contains
>> the code to make "iwconfig wlan0 power on" work, the actual power
>> management is missing.
>>
>> I just did some tests using powertop to see if I'm right. With the old
>> pre-iwlegacy driver, the difference between "iwconfig wlan0 power on"
>> and "...  power off" is more then 0,8W, which is ~10% of the total idle
>> power usage of my X61s with dimmed screen.  With a current kernel and
>> your patch, I can't measure a difference between "iwconfig wlan0 power
>> on" and "...  power off".  To me it seems that the patch is pretty
>> useless, at least on 4965AGN hardware.
>
> Yes, we do not send any command to put hardware in sleep mode when
> mac80211 enable PS.
>
>> It would be really nice to have proper power management in a current
>> kernel, as the laptop gets noticeably hotter with the current iwlegacy
>> driver.  That's why I still use a 3.1.10 kernel with an old
>> forward-ported iwlagn driver.
>
> Could you try this experimental patch? (...)

I am trying the iwlegacy powersave patch along with CPU scheduler BFS
and IO scheduler BFQ.

I've got this today:

Jun 09 00:51:34 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 51 is out of range [0-256] 51 51
Jun 09 00:51:34 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 52 is out of range [0-256] 51 51
(...)
Jun 09 00:51:38 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 219 is out of range [0-256] 57 51
Jun 09 00:51:38 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 220 is out of range [0-256] 57 51

Jun 09 00:51:34 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 51 is out of range [0-256] 51 51
Jun 09 00:51:34 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 52 is out of range [0-256] 51 51
(...)
Jun 09 00:51:38 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 254 is out of range [0-256] 58 51
Jun 09 00:51:38 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 255 is out of range [0-256] 58 51
Jun 09 00:51:38 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 0 is out of range [0-256] 58 51
Jun 09 00:51:38 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 1 is out of range [0-256] 58 51
(...)
Jun 09 00:51:39 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 49 is out of range [0-256] 58 51
Jun 09 00:51:39 s2 kernel: iwl3945 0000:02:00.0: Read idx for DMA
queue txq_id (2) idx 50 is out of range [0-256] 58 51

$ uname -a
Linux s2 3.9.4-301.local.fc19.i686

I have just made a clean boot (as in, this has not happened after a
resume for suspend or hibernation).

May it be related to the patch? Or may heavy IO with out-of-tree CPU
scheduler BFS and out-of-tree IO scheduler BFQ be responsible for the
warnings?

Thanks in Advance,
-- 
Pedro Francisco