From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: Not understand some in htb_do_events function Date: Wed, 16 Jan 2008 06:15:34 +0100 Message-ID: <478D92F6.6070201@trash.net> References: <478C86E6.3050508@bigtelecom.ru> <478C87D9.1010305@trash.net> <478CA02A.1070308@cdi.cz> <478CD741.7040004@trash.net> <478D2C85.2090008@cdi.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: Badalian Vyacheslav , netdev@vger.kernel.org To: Martin Devera Return-path: Received: from stinky.trash.net ([213.144.137.162]:60029 "EHLO stinky.trash.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750912AbYAPFPx (ORCPT ); Wed, 16 Jan 2008 00:15:53 -0500 In-Reply-To: <478D2C85.2090008@cdi.cz> Sender: netdev-owner@vger.kernel.org List-ID: Martin Devera wrote: >> >> So this was meant to protect against endless loops? >> >>> We want way to smooth big burst of events over more dequeue invocations >>> in order to not slow dequeue too much. Constant 500 is max. allowed >>> "slowdown" of dequeue. >>> Any bright idea how to do it more elegant, Patrick ? >> >> >> Unfortunately not, but I believe simply removing the limit >> completely would be better than picking an arbitary value. > > Grrr my comp crashed while I was writing this mail. Well the second > attempt. > When we allow unlimited events per dequeue, then there is case where > all N classes in qdisc can be in the event queue with the same target > time. Then they will all be acted on in the loop within single dequeue, > costing us say some milliseconds. Additionaly, it tends to repeat itself > then in cycles. I see. > Maybe it is acceptable but it seemed to me as rather big latency. > Thus I wanted to do only limited work per dequeue call. One possibility > is to remove the limit and "see what happend in wild". > > What do u think about to do limited no of transitions and then schedule > tasklet to do the rest (again in limited buckets) ? Alternatively we could just remove the printk and do what you suggested first, return q->now + 1 to immediately continue processing, but send out a packet first.