netdev - Re: [PATCH] net_sched: htb: do not mix 1ns and 64ns time units

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Date:	Tue, 04 Jun 2013 13:50:31 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jesper Dangaard Brouer <jbrouer@...hat.com>
Cc:	netdev@...r.kernel.org, Jesper Dangaard Brouer <brouer@...hat.com>,
	Stephen Hemminger <stephen@...workplumber.org>,
	Jiri Benc <jbenc@...hat.com>, David Miller <davem@...hat.com>,
	j.vimal@...il.com, Michal Soltys <soltys@....info>,
	Mike Frysinger <vapier@...too.org>,
	Jussi Kivilinna <jussi.kivilinna@...et.fi>,
	Patrick McHardy <kaber@...sh.net>,
	Jiri Pirko <jpirko@...hat.com>,
	Toke Høiland-Jørgensen <toke@...e.dk>,
	Dave Taht <dave.taht@...il.com>, bloat@...ts.bufferbloat.net,
	Dan Siemon <dan@...erfire.com>,
	Jim Gettys <jg@...edesktop.org>,
	Steven Barth <cyrus@...nwrt.org>, Felix Fietkau <nbd@....name>
Subject: Re: [PATCH] net_sched: htb: do not mix 1ns and 64ns time units

On Tue, 2013-06-04 at 22:21 +0200, Jesper Dangaard Brouer wrote:

> But how is this 64-bit usage going to affect performance for smaller
> ARM/MIPS based home routers, where shaping at these low rates is more
> relevant?  (I'm just asking because I don't know, and just test this
> on a 24-CPU machine).

Well, by definition shaping at low rates is mostly using the timer
infra, and its already 64bit. You'll hardly spend time in HTB.

Note that psched_time_t is already 64bit wide.

Only psched_tdiff_t is 'unsigned long', and the change I made in this
patch will not change performance even on 32bit hosts.



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