From: Zoltan Kiss <zoltan.kiss@citrix.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Wei Liu <wei.liu2@citrix.com>, <netdev@vger.kernel.org>,
<xen-devel@lists.xen.org>, David Vrabel <david.vrabel@citrix.com>,
Konrad Wilk <konrad.wilk@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Stefan Bader <stefan.bader@canonical.com>
Subject: Re: [PATCH net-next] xen-netfront: try linearizing SKB if it occupies too many slots
Date: Fri, 16 May 2014 17:51:46 +0100 [thread overview]
Message-ID: <53764222.6070705@citrix.com> (raw)
In-Reply-To: <1400258829.7973.209.camel@edumazet-glaptop2.roam.corp.google.com>
On 16/05/14 17:47, Eric Dumazet wrote:
> On Fri, 2014-05-16 at 17:29 +0100, Zoltan Kiss wrote:
>> On 16/05/14 16:34, Wei Liu wrote:
>>>
>>> It works, at least in this Redis testcase. Could you explain a bit where
>>> this 56000 magic number comes from? :-)
>>>
>>> Presumably I can derive it from some constant in core network code?
>>
>> I guess it just makes more unlikely to have packets with problematic layout. But the following packet would still fail:
>> linear buffer : 80 bytes, on 2 pages
>> 17 frags, 80 bytes each, each spanning over page boundary.
>
> How would you build such skbs ? Its _very_ difficult, you have to be
> very very smart to hit this.
I wouldn't build such skbs, I would expect the network stack to create
such weird things sometimes :)
The goal here is to prepare and handle the worst case scenarios as well.
>
> Also reducing gso_max_size made sure order-5 allocations would not be
> attempted in this unlikely case.
But reducing the gso_max_size would have a bad impact on the general
network throughput, right?
next prev parent reply other threads:[~2014-05-16 16:51 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-16 11:08 [PATCH net-next] xen-netfront: try linearizing SKB if it occupies too many slots Wei Liu
2014-05-16 13:04 ` Eric Dumazet
2014-05-16 13:11 ` Wei Liu
2014-05-16 14:21 ` Eric Dumazet
2014-05-16 14:36 ` Wei Liu
2014-05-16 15:22 ` Eric Dumazet
2014-05-16 15:34 ` Wei Liu
2014-05-16 16:29 ` Zoltan Kiss
2014-05-16 16:47 ` Eric Dumazet
2014-05-16 16:51 ` Zoltan Kiss [this message]
2014-05-16 17:00 ` Eric Dumazet
2014-05-16 16:54 ` Wei Liu
2014-05-19 16:47 ` Zoltan Kiss
2014-05-30 8:06 ` Stefan Bader
2014-05-30 12:07 ` Zoltan Kiss
2014-05-30 12:37 ` Stefan Bader
2014-07-02 12:23 ` Stefan Bader
2014-07-02 13:12 ` Zoltan Kiss
2014-05-30 12:11 ` Wei Liu
2014-05-30 12:28 ` Stefan Bader
2014-05-30 12:38 ` Wei Liu
2014-05-30 12:28 ` David Laight
2014-05-30 12:35 ` Wei Liu
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