netdev - Re: [PATCH V2] sch_red: fix red_calc_qavg_from_idle

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Message-ID: <CAA93jw7TZj3Gd-KiVwr3Qwta4RpDKKV9QxGc+fyGc_+-9r1tLw@mail.gmail.com>
Date:	Wed, 30 Nov 2011 23:35:01 +0100
From:	Dave Taht <dave.taht@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Stephen Hemminger <shemminger@...tta.com>
Subject: Re: [PATCH V2] sch_red: fix red_calc_qavg_from_idle_time

On Wed, Nov 30, 2011 at 11:10 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Since commit a4a710c4a7490587 (pkt_sched: Change PSCHED_SHIFT from 10 to
> 6) it seems RED/GRED are broken.

> red_calc_qavg_from_idle_time() computes a delay in us units, but this
> delay is now 16 times bigger than real delay, so the final qavg result
> smaller than expected.

I've been scratching my head about RED's behavior for a while.

Pre-BQL I was unable to even see red behave, so we're still ahead
on this game.

I will apply this patch to the ongoing work. Thank you.

http://www.bufferbloat.net/issues/312

One of my other problems is when I try to size red (or choke) appropriately
(or so I think) for GigE bandwidths and queue depths, it would fail
to calculate the ewma value.


-- 
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
FR Tel: 0638645374
http://www.bufferbloat.net
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