On 5/4/2017 5:07 PM, Scott Wood wrote: > On Thu, 2017-05-04 at 06:58 +0200, Karim Eshapa wrote: >> + stop = jiffies + 10000; >> + /* >> + * if MR was full and h/w had other FQRNI entries to produce, we >> + * need to allow it time to produce those entries once the >> + * existing entries are consumed. A worst-case situation >> + * (fully-loaded system) means h/w sequencers may have to do 3-4 >> + * other things before servicing the portal's MR pump, each of >> + * which (if slow) may take ~50 qman cycles (which is ~200 >> + * processor cycles). So rounding up and then multiplying this >> + * worst-case estimate by a factor of 10, just to be >> + * ultra-paranoid, goes as high as 10,000 cycles. NB, we consume >> + * one entry at a time, so h/w has an opportunity to produce new >> + * entries well before the ring has been fully consumed, so >> + * we're being *really* paranoid here. >> + */ > OK, upon reading this more closely it seems the intent was to delay for 10,000 > *processor cycles* and somehow that got turned into 10,000 jiffies (which is > 40 seconds at the default Hz!). We could just replace this whole thing with > msleep(1) and still be far more paranoid than was originally intended. > > Claudiu and Roy, any comments? Yes the timing here is certainly off, the code changed a few times since the comment was originally written. An msleep(1) seems reasonable here to me.
Roy > > -Scott > >
