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Subject: Re: [RFC v2] mac80211: implement eBDP algorithm to fight bufferbloat
From: Nathaniel Smith <njs@pobox.com>
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On Fri, Feb 25, 2011 at 10:21 AM, Nathaniel Smith <njs@pobox.com> wrote:
> static u64 _ktime_diff_to_now_and_unstash(ktime_t then, int * enqueued) {
>
> =C2=A0 =C2=A0 =C2=A0 =C2=A0timespec ts_then =3D ktime_to_timespec(then);
> =C2=A0 =C2=A0 =C2=A0 =C2=A0timespec ts_now =3D ktime_to_timespec(ktime_ge=
t());
> =C2=A0 =C2=A0 =C2=A0 =C2=A0*enqueued =3D ts_then.tv_sec >> LATENCY_BITS;
> =C2=A0 =C2=A0 =C2=A0 =C2=A0ts_then.tv_sec &=3D (1 << LATENCY_BITS) - 1;
> =C2=A0 =C2=A0 =C2=A0 =C2=A0ts_now.tv_sec &=3D (1 << LATENCY_BITS) - 1;
> =C2=A0 =C2=A0 =C2=A0 =C2=A0if (ts_now.tv_sec < ts_then.tv_sec)
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0ts_now.tv_sec +=3D=
 (1 << LATENCY_BITS);
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 timespec_sub(ts_now, ts_then);
> }

Err, plus the 'return timespec_to_ns(...)' on the last line, that I
was trying to add when my computer suddenly decided I wanted to send
the message. How embarrassing.

Anyway, not sure this is a *good* idea, but it should work. Hopefully
we don't actually need to measure latencies > 256 seconds in this
context...

-- Nathaniel