Hi Stanislaw, On Mon, 2010-10-18 at 05:12 -0700, Stanislaw Gruszka wrote: > Hi Wey > > > activity is too small time for device. Moreover we have unlikely but > > possible situation when device is fully functional, but read_ptr will > > wrap by accident to q->last_read_ptr on every check. > > > > I think, better solution would be something like in rt2x00 or in > > net/sched/sch_generic.c (however rt2x00 is easier to understand). It is > > based on time stamp. When we get tx complete notification from hardware > > (and incise read_ptr) mark the time stamp. In watchdog, which tick > > periodically, check if queue is not empty and if current time is > > bigger than time_stamp + time_out, if it is - firmware hung. More > > smaller watchog tick give more precise hung detect (with disadvantage > > of more cpu usage). > > > > > > Me too not really like the current "monitor" approach, some thought about the design you propose. > > > > 1. "time_out" is something need to be define and has the similar problem like what we have today since different devices has different behavior. For example, in WiFi/BT combo case, the queue might not move for a while if BT traffic load is high > > Sure. > > However new watchdog could be more precise. Currently if hung will > happen just after watchdog tick we are detecting it in time about 2 > ticks i.e. 10s, or when happen just before the tick we detect the hang > in 1 tick i.e. 5s, what gives 100% inaccuracy. New design can be much > more precise. > > > 2. I don't really see much of "cpu usage" impact if we have a reasonable watchdog timer. But it is all relative. > > Ohh, I was talking about cpu usage in new design I described. > > > > > By saying that, I think using timestamp might give more cleaner design, but still has the similar issues. > > Ok, if Intel have no plan to change the monitor recovery and have nothing > against my watchdog approach, I'm going to cook some patches. Pleas do so and please do let us review it. I am very happy having you looking at the iwlwifi driver and give great improvement. Thank you very much Wey -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
