From: David Miller <davem@davemloft.net>
To: David.Laight@ACULAB.COM
Cc: puzman@gmail.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] pch_gbe: Fix transmit queue management
Date: Mon, 02 Dec 2013 11:16:00 -0500 (EST) [thread overview]
Message-ID: <20131202.111600.1622488165507147936.davem@davemloft.net> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6026B744F@saturn3.aculab.com>
From: "David Laight" <David.Laight@ACULAB.COM>
Date: Mon, 2 Dec 2013 10:04:49 -0000
> I know you like ethernet drivers to work this way, but requiring enough
> descriptors for a maximally fragmented packet requires a difficult
> calculation and will cause the tx queue to be stopped unnecessarily.
...
> Isn't there also a new skb structure that allows lists of fragments?
> That might need even more descriptors for a worst case transmit.
Fragment lists are not to be found in the transmit function of the
driver. Any such SKBs will be linearized or similar first. We do
want to support them in some capacity in the future, but right now
we don't.
And here we're not talking about a USB driver, so using the rather
extreme example of the USB segmentation restrictions is not really
appropriate.
This is a pretty standard ethernet driver, which can use a one to
one correspondance between the segmentation count of the SKB and
the number of TX descriptors that will be used.
There is a large precedence for doing things this way and in this
particular case it's straightforward.
next prev parent reply other threads:[~2013-12-02 16:16 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-27 23:29 [PATCH] pch_gbe: Fix transmit queue management Ondrej Puzman
2013-11-27 23:29 ` [PATCH] pch_gbe: Remove tx_queue_len setting from the driver Ondrej Puzman
2013-11-27 23:29 ` [PATCH] pch_gbe: Add DQL support to " Ondrej Puzman
2013-11-27 23:29 ` [PATCH] pch_gbe: Fix: Link configuration in module parameters was ignored Ondrej Puzman
2013-11-28 4:39 ` [PATCH] pch_gbe: Remove tx_queue_len setting from the driver David Miller
2013-11-28 9:44 ` [PATCH 0/4] pch_gbe fixes and enhancements Ondrej Puzman
2013-11-29 21:43 ` David Miller
2013-11-28 9:44 ` [PATCH 1/4] pch_gbe: Fix transmit queue management Ondrej Puzman
2013-11-29 21:42 ` David Miller
2013-11-30 22:41 ` Ondřej Pužman
2013-12-02 10:04 ` David Laight
2013-12-02 16:16 ` David Miller [this message]
2013-12-02 16:33 ` Eric Dumazet
2013-12-02 16:51 ` [PATCH] net: do not pretend FRAGLIST support Eric Dumazet
2013-12-02 22:17 ` David Miller
2013-12-02 16:51 ` [PATCH 1/4] pch_gbe: Fix transmit queue management Eric Dumazet
2013-11-28 9:44 ` [PATCH 2/4] pch_gbe: Remove tx_queue_len setting from the driver Ondrej Puzman
2013-11-28 9:44 ` [PATCH 3/4] pch_gbe: Add DQL support to " Ondrej Puzman
2013-11-28 9:44 ` [PATCH 4/4] pch_gbe: Fix: Link configuration in module parameters was ignored Ondrej Puzman
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