From: Eric Dumazet <eric.dumazet@gmail.com>
To: Dave Taht <dave.taht@gmail.com>
Cc: "Steinar H. Gunderson" <sesse@samfundet.no>,
bloat <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] Replacing pfifo_fast? (and using sch_fq + hystart fixes)
Date: Mon, 24 Mar 2014 17:18:27 -0700 [thread overview]
Message-ID: <1395706707.12610.101.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <CAA93jw5GLNEaiVyLo4cyQ0cucdsg_QmRB5JVmin8t3kJdAB4ow@mail.gmail.com>
On Mon, 2014-03-24 at 16:10 -0700, Dave Taht wrote:
> One of my concerns is that sch_fq is (?) currently inadaquately
> explored in the case of wifi - as best as I recall there were a
> ton of drivers than cloned and disappeared the skb deep
> in driver buffers, making fq_codel a mildly better choice...
Thats because fq_codel do not add delays (other than RR scheduling among
flows). Remember, if no queue is in fq_codel itself, there nothing we
can control using codel law.
In the fq case, packets are held in the qdisc the needed time and
delivered 'at the right time' to whatever lower device. Part of the
'original TCP bursts' are amortized by sch_fq before reaching device.
TCP pacing has nothing to do with additional delays imposed in various
wifi drivers. Consider a packet in wifi queue exactly as if it was
already sent on the network.
next prev parent reply other threads:[~2014-03-25 0:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-24 17:09 Dave Taht
2014-03-24 17:41 ` Eric Dumazet
2014-03-24 23:10 ` Dave Taht
2014-03-25 0:18 ` Eric Dumazet [this message]
2014-03-25 0:38 ` Dave Taht
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