From: Denys Fedoryschenko <denys@visp•net.lb>
To: Jarek Poplawski <jarkao2@gmail•com>
Cc: Stephen Hemminger <shemminger@linux-foundation•org>,
netdev@vger•kernel.org
Subject: Re: [PATCH] [RESEND] iproute2 : invalid burst/cburst calculation with hrtimers
Date: Thu, 5 Feb 2009 11:01:35 +0200 [thread overview]
Message-ID: <200902051101.35327.denys@visp.net.lb> (raw)
In-Reply-To: <20090205073832.GA4305@ff.dom.local>
Well, i don't know well what's wrong, but:
I have enough powerful router, 2x Quad Core 2 - 2.8 Ghz
4 x e1000e
And if i just try to shape interface for 200 Mbps with default iproute2 from
git (and latest stable release same situation), i am getting too low
burst/cburst. Sometimes it is even miscalculated (it can become 1500 byte,
sometimes, while 1600 is minimum) , because yes, Stephen right, it needs
float.
BUT.
Even i set manually twice more burst/cburst, it is just not enough for 200
Mbps. I am checking on Cisco, rate is reaching max 180-185Mbps, and even on
this rate buffering in qdiscs and as result jittering hard.
So this 100 bytes, which probably missing, really doesn't matter.
With 1000 HZ i have
class htb 1:10 parent 1:2 rate 220000Kbit ceil 220000Kbit burst 29067b cburst
29067b
Sent 14027734219153 bytes 590886842 pkt (dropped 0, overlimits 0 requeues 0)
rate 122452Kbit 17131pps backlog 0b 0p requeues 0
lended: 171333348 borrowed: 0 giants: 0
tokens: 980 ctokens: 980
And it works quite well and precise.
P.S. Maybe a case, when some guy was not able to reach his gigabit with HTB
shaper, i remember there was flowing some discussing, was somehow similar as
my case.
On Thursday 05 February 2009 09:38:32 Jarek Poplawski wrote:
>
> I think HZ doesn't matter much in this place, because if it's ever
> triggered there is something really wrong and precision is lost.
> Anyway, this place was changed a bit in net-next.
>
> I guess I could misunderstand your previous question. If you mean this
> previous thread, then yes, IMHO CONFIG_HZ should matter for precision
> (especially places where similar loops use all such jiffies in "normal"
> situations). On the other hand, maybe I'm wrong, but using HZ 1000
> with HIGH_RES_TIMERS looks quite obvious to me...
>
> Jarek P.
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger•kernel.org
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next prev parent reply other threads:[~2009-02-05 9:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-02 17:26 [PATCH] [RESEND] iproute2 : invalid burst/cburst calculation with hrtimers Denys Fedoryschenko
2009-02-02 18:07 ` Stephen Hemminger
2009-02-02 18:21 ` Denys Fedoryschenko
2009-02-04 21:20 ` Jarek Poplawski
2009-02-04 21:53 ` Jarek Poplawski
2009-02-04 22:26 ` Denys Fedoryschenko
2009-02-04 22:49 ` Jarek Poplawski
2009-02-04 23:24 ` Denys Fedoryschenko
2009-02-05 7:38 ` Jarek Poplawski
2009-02-05 9:01 ` Denys Fedoryschenko [this message]
2009-02-05 10:08 ` Jarek Poplawski
2009-02-05 11:09 ` Denys Fedoryschenko
2009-02-05 11:56 ` Jarek Poplawski
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