From: Yang Yingliang <yangyingliang@huawei•com>
To: Eric Dumazet <eric.dumazet@gmail•com>,
David Miller <davem@davemloft•net>
Cc: <netdev@vger•kernel.org>, <dingtianhong@huawei•com>
Subject: Re: [PATCH RFC] net: decrease the length of backlog queue immediately after it's detached from sk
Date: Mon, 11 Apr 2016 22:42:41 +0800 [thread overview]
Message-ID: <570BB7E1.5070004@huawei.com> (raw)
In-Reply-To: <1460135072.6473.441.camel@edumazet-glaptop3.roam.corp.google.com>
On 2016/4/9 1:04, Eric Dumazet wrote:
> On Fri, 2016-04-08 at 12:53 -0400, David Miller wrote:
>> From: Eric Dumazet <eric.dumazet@gmail•com>
>> Date: Fri, 08 Apr 2016 07:44:25 -0700
>>
>>> On Fri, 2016-04-08 at 19:18 +0800, Yang Yingliang wrote:
>>>
>>>> I expand tcp_adv_win_scale and tcp_rmem. It has no effect.
>>>
>>> Try :
>>>
>>> echo -2 >/proc/sys/net/ipv4/tcp_adv_win_scale
>>>
>>> And restart your flows.
>>
>> I'm honestly beginning to suspect a bug in their driver and how they
>> handle skb->truesize.
>>
>> Yang, until you show us the driver you are using and how is handles
>> receive packets, we are largely in the dark about a major component
>> of this issue and that is entirely unfair to us.
>
> Apparently their skb->truesize and skb->len combinations are correct.
>
> I suspect an issue with rcvbuf autouning on a bidirectional tcp traffic.
> We mostly focus on unidirectional flows, but they seem to use a mixed
> case.
>
> Also, fact that sendmsg() locks the socket for the duration of the call
> is problematic : I suspect their issues would mostly disappear by using
> smaller chunk sizes (ie 64KB per sendmsg() instead of 256KB).
It's less packets dropping with using 64KB chunk.
>
> We also could add resched points in sendmsg() (processing backlog if it
> gets too hot), but I fear this would slow down the fast path.
>
>
>
>
>
next prev parent reply other threads:[~2016-04-11 14:44 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-30 5:16 [PATCH RFC] net: decrease the length of backlog queue immediately after it's detached from sk Yang Yingliang
2016-03-30 5:25 ` Eric Dumazet
2016-03-30 5:34 ` Eric Dumazet
2016-03-30 5:56 ` Yang Yingliang
2016-03-30 13:47 ` Eric Dumazet
2016-04-07 5:59 ` Yang Yingliang
2016-04-07 10:21 ` Eric Dumazet
2016-04-07 14:51 ` Eric Dumazet
2016-04-08 11:18 ` Yang Yingliang
2016-04-08 14:44 ` Eric Dumazet
2016-04-08 16:53 ` David Miller
2016-04-08 17:04 ` Eric Dumazet
2016-04-11 14:42 ` Yang Yingliang [this message]
2016-04-11 11:57 ` Yang Yingliang
2016-04-11 12:13 ` Eric Dumazet
2016-04-12 2:59 ` Yang Yingliang
2016-04-12 12:31 ` Yang Yingliang
2016-04-13 2:42 ` Eric Dumazet
2016-03-30 5:38 ` Yang Yingliang
2016-03-30 12:56 ` Sergei Shtylyov
2016-04-07 6:01 ` Yang Yingliang
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