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From: Francois Romieu <romieu@fr.zoreil.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: netdev@vger.kernel.org, Hayes Wang <hayeswang@realtek.com>
Subject: Re: [RFC] r8169 : why SG / TX checksum are default disabled
Date: Wed, 18 Jul 2012 01:40:37 +0200	[thread overview]
Message-ID: <20120717234037.GA26972@electric-eye.fr.zoreil.com> (raw)
In-Reply-To: <1342564781.2626.1264.camel@edumazet-glaptop>

Eric Dumazet <eric.dumazet@gmail.com> :
[...]
> I was wondering why Scatter Gather (NETIF_F_SG) and TX checksum
> (NETIF_F_IP_CSUM) were disabled by default on r8169.

It was not unconditionally stable. For a number of reasons:
- incompatibility with jumbo frames.
  rtl_chip_infos now allows to take care of it
- lack of support for chipset dependent Tx descriptor 
  rtl_tx_desc_info handles it. There are yet a few unused ipv6 bits. No idea
  how useable they are.
- some false alarms due to different issues and probably some others
  I could hunt for in the archives.

> Couldnt we enable them by default, maybe for a whitelist of "good"
> nics ?

Sure.

Hayes, should we not add into the kernel driver something similar to
the rtl8168_start_xmit::skb_checksum_help stuff in Realtek's 8168 driver ?
There seems to be a bug for (skb->len < 60 && RTL_GIGA_MAC_VER_34.

> (I found that activating them with ethtool automatically enables GSO,
>  and performance with GSO is not good)

It's still an improvement though, isn't it ?

-- 
Ueimor

  reply	other threads:[~2012-07-17 23:53 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-17 22:39 [RFC] r8169 : why SG / TX checksum are default disabled Eric Dumazet
2012-07-17 23:40 ` Francois Romieu [this message]
2012-07-18  6:45   ` hayeswang
2012-07-18 16:23     ` David Miller
2012-07-18 20:12       ` Francois Romieu
2012-07-18 20:28         ` David Miller
2012-07-18 21:44           ` Francois Romieu
2012-07-18 22:05             ` Eric Dumazet
2012-07-18 22:24               ` David Miller
2012-07-20  7:14                 ` hayeswang
2012-07-20 10:08                   ` Francois Romieu
2012-07-20 16:01                     ` hayeswang
2012-07-20 16:28                       ` David Miller
2012-07-20 21:01                       ` Francois Romieu
2012-07-24  6:34                         ` hayeswang
2012-07-24  6:59                           ` David Miller
2012-07-25  2:10                             ` hayeswang
2012-07-20 16:17                   ` David Miller
2012-07-20  2:11         ` hayeswang
2012-07-18  8:55   ` Eric Dumazet

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