On Tue, 2015-02-10 at 04:54 -0800, Eric Dumazet wrote:
> Hi Michal
>
> This is almost it ;)
>
> As I said you must do this using u64 arithmetics, we still support 32bit
> kernels.
>
> Also, >> 20 instead of / 1000000 introduces a 5% error, I would use a
> plain divide, as the compiler will use a reciprocal divide (ie : a
> multiply)
>
> We use >> 10 instead of /1000 because a 2.4 % error is probably okay.
>
> ewma_add(&ar->tx_delay_us,
> ktime_to_ns(ktime_sub(ktime_get(),
> skb_cb->stamp)) /
> NSEC_PER_USEC);
btw I suspect this wont compile on 32 bit kernel
You need to use do_div() as well :
u64 val = ktime_to_ns(ktime_sub(ktime_get(),
skb_cb->stamp));
do_div(val, NSEC_PER_USEC);
ewma_add(&ar->tx_delay_us, val);
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