THIS is what I did at the beginning. But is seem me to be some thing wrong. So I put a static value in skb->tstamp instead of ktime_get_real() for debug purpose. And I was still becoming the amount of second, microsecond since 1970. We are back to my initial mail ! The value of skb->tsamp doesn't seems to be returned by ioctl(). 2007/11/13, Eric Dumazet <dada1@xxxxxxxxxxxxx>: > Antoine Zen-Ruffinen a écrit : > > This is exactly my problem : The driver of the network card I am using > > (see rt2x00.serialmonkey.com) do the minimum in the hardware interrupt > > (not filling skb->tstamp). Then netif_rx() is called later using a > > tasklet (also not filling skb->tstamp). As it seem to me (maybe I am > > wrong, if so please tell), the elapse time between the actual frame > > arrival and the time where netif_rx() do net_timestamp(skb) is not > > predicable !? > > > > Else, I would like to thank you to spend time helping me. > > > > > > > A tasklet could process the skb much later than corresponding IRQ, > depending on various things > (other tasks/softirqs on system with higher priorities). So yes, it is > not predictable at all. > > Usually it doesnt matter, but if your business depends on precise tstamps, > then just do skb->tstamp = ktime_get_real(); in IRQ handler (but it will > slow it a bit, > depending on how fast is ktime_get_real() on the target machine) > netif_rx() wont overwrite it. > > skb = dev_alloc_skb(desc.size + NET_IP_ALIGN); > if (!skb) > return; > skb->tstamp = ktime_get_real(); /* do it before other copies */ > skb_reserve(skb, NET_IP_ALIGN); > skb_put(skb, desc.size); > memcpy(skb->data, entry->data_addr, desc.size); > > ... > > > > > > - To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
