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From: Vladimir Oltean <olteanv@gmail.com>
To: 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
Subject: Re: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum
Date: Thu, 15 Jul 2021 14:49:08 +0300	[thread overview]
Message-ID: <20210715114908.ripblpevmdujkf2m@skbuf> (raw)
In-Reply-To: <trinity-84a570e8-7b5f-44f7-b10c-169d4307d653-1626347772540@3c-app-gmx-bap31>

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?

  reply	other threads:[~2021-07-15 11:49 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14 19:17 [PATCH 0/2] Fixes for KSZ DSA switch Lino Sanfilippo
2021-07-14 19:17 ` [PATCH 1/2] net: dsa: tag_ksz: linearize SKB before adding DSA tag Lino Sanfilippo
2021-07-14 19:17 ` [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum Lino Sanfilippo
2021-07-14 19:48   ` Vladimir Oltean
2021-07-14 20:15     ` Andrew Lunn
2021-07-15  6:54       ` Vladimir Oltean
2021-07-15 11:16         ` Aw: " Lino Sanfilippo
2021-07-15 11:49           ` Vladimir Oltean [this message]
2021-07-15 13:04             ` Lino Sanfilippo
2021-07-15 13:12               ` Vladimir Oltean
2021-07-15 13:34                 ` Aw: " Lino Sanfilippo
2021-07-15 13:08         ` Andrew Lunn
2021-07-15 14:36           ` Vladimir Oltean
2021-07-15 15:50             ` Andrew Lunn
2021-07-19  8:20             ` Aw: " Lino Sanfilippo
2021-07-19  8:24               ` Vladimir Oltean
2021-07-15 16:24           ` Florian Fainelli
2021-07-15 23:23 ` [PATCH 0/2] Fixes for KSZ DSA switch Florian Fainelli
2021-07-16  8:49   ` Aw: " Lino Sanfilippo

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