From: Paolo Valente <paolo.valente@unimore.it>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: jhs@mojatatu.com, davem@davemloft.net, shemminger@vyatta.com,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
rizzo@iet.unipi.it, fchecconi@gmail.com
Subject: Re: [PATCH RFC] pkt_sched: enable QFQ to support TSO/GSO
Date: Mon, 29 Oct 2012 12:24:51 +0100 [thread overview]
Message-ID: <508E6783.2080403@unimore.it> (raw)
In-Reply-To: <508E63AD.20803@gmail.com>
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@unimore.it>
>
>
> Please respect people who helps you to test it:
>
> Tested-by: Cong Wang <amwang@redhat.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/ |
-----------------------------------------------------------
next prev parent reply other threads:[~2012-10-29 11:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-29 8:51 [PATCH RFC] pkt_sched: enable QFQ to support TSO/GSO Paolo Valente
2012-10-29 11:08 ` Cong Wang
2012-10-29 11:24 ` Paolo Valente [this message]
2012-10-29 11:31 ` Cong Wang
-- strict thread matches above, loose matches on Subject: below --
2012-10-30 6:00 Paolo Valente
2012-10-30 14:24 ` Stephen Hemminger
2012-11-05 8:41 ` Cong Wang
2012-11-05 16:46 ` David Miller
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