lkml.org 
[lkml]   [2021]   [Jul]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectAw: Re: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum
Date


> Gesendet: Donnerstag, 15. Juli 2021 um 13:49 Uhr
> Von: "Vladimir Oltean" <olteanv@gmail.com>
> An: "Lino Sanfilippo" <LinoSanfilippo@gmx.de>
> Cc: "Andrew Lunn" <andrew@lunn.ch>, woojung.huh@microchip.com, UNGLinuxDriver@microchip.com, vivien.didelot@gmail.com, f.fainelli@gmail.com, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
> Betreff: Re: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum
>
> On Thu, Jul 15, 2021 at 01:16:12PM +0200, Lino Sanfilippo wrote:
> > Sure, I will test this solution. But I think NETIF_F_FRAGLIST should also be
> > cleared in this case, right?
>
> Hmm, interesting question. I think only hns3 makes meaningful use of
> NETIF_F_FRAGLIST, right? I'm looking at hns3_fill_skb_to_desc().
> Other drivers seem to set it for ridiculous reasons - looking at commit
> 66aa0678efc2 ("ibmveth: Support to enable LSO/CSO for Trunk VEA.") -
> they set NETIF_F_FRAGLIST and then linearize the skb chain anyway. The
> claimed 4x throughput benefit probably has to do with less skbs
> traversing the stack? I don't know.
>
> Anyway, it is hard to imagine all the things that could go wrong with
> chains of IP fragments on a DSA interface, precisely because I have so
> few examples to look at. I would say, header taggers are probably fine,
> tail taggers not so much, so apply the same treatment as for NETIF_F_SG?
>

Please note that skb_put() asserts that the SKB is linearized. So I think we
should rather clear both NETIF_F_FRAGLIST and NETIF_F_SG unconditionally since also
header taggers use some form of skb_put() dont they?






\
 
 \ /
  Last update: 2021-07-15 15:05    [W:0.948 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site