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Date: Mon, 29 Oct 2012 12:24:51 +0100 From: Paolo Valente <paolo.valente@...more.it> To: Cong Wang <xiyou.wangcong@...il.com> CC: jhs@...atatu.com, davem@...emloft.net, shemminger@...tta.com, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, rizzo@....unipi.it, fchecconi@...il.com Subject: Re: [PATCH RFC] pkt_sched: enable QFQ to support TSO/GSO Il 29/10/2012 12:08, Cong Wang ha scritto: > On 10/29/2012 04:51 PM, Paolo Valente wrote: >> Hi, >> if the max packet size for some class (configured through tc) is >> violated by the actual size of the packets of that class, then QFQ >> would not schedule classes correctly, and the data structures >> implementing the bucket lists may get corrupted. This problem occurs >> with TSO/GSO even if the max packet size is set to the MTU, and is, >> e.g., the cause of the failure reported in [1]. Two patches have been >> proposed to solve this problem in [2], one of them is a preliminary >> version of this patch. >> >> This patch addresses the above issues by: 1) setting QFQ parameters to >> proper values for supporting TSO/GSO (in particular, setting the >> maximum possible packet size to 64KB), 2) automatically increasing the >> max packet size for a class, lmax, when a packet with a larger size >> than the current value of lmax arrives (a notification is also appended >> to the log). >> >> The drawback of the first point is that the maximum weight for a class >> is now limited to 4096, which is equal to 1/16 of the maximum weight >> sum. >> >> Finally, this patch also forcibly caps the timestamps of a class if >> they are too high to be stored in the bucket list. This capping, taken >> from QFQ+ [3], handles the unfrequent case described in the comment to >> the function slot_insert. >> >> [1] http://marc.info/?l=linux-netdev&m=134968777902077&w=2 >> [2] http://marc.info/?l=linux-netdev&m=135096573507936&w=2 >> [3] http://marc.info/?l=linux-netdev&m=134902691421670&w=2 >> >> Signed-off-by: Paolo Valente <paolo.valente@...more.it> > > > Please respect people who helps you to test it: > > Tested-by: Cong Wang <amwang@...hat.com> Oops, really sorry about that. I did not mean to hide your contribution. I am just not familiar with the process. > > I tested it again just in case... Thanks again > > By the way, one nit below: > > >> + if (unlikely(cl->lmax < qdisc_pkt_len(skb))) { >> + pr_notice("qfq: increasing maxpkt from %u to %u for class %u", >> + cl->lmax, qdisc_pkt_len(skb), cl->common.classid); >> + qfq_update_reactivate_class(q, cl, cl->inv_w, >> + qdisc_pkt_len(skb), 0); >> + } > > > Seems the log level KERN_NOTICE is overkill, normal users don't care > about these information, so s/pr_notice/pr_debug/. > Thanks, I will integrate this and possible other suggestions in a new version of the patch. > > Thanks! > > -- ----------------------------------------------------------- | Paolo Valente | | | Algogroup | | | Dip. Ing. Informazione | tel: +39 059 2056318 | | Via Vignolese 905/b | fax: +39 059 2056129 | | 41125 Modena - Italy | | | home: http://algo.ing.unimo.it/people/paolo/ | ----------------------------------------------------------- -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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