From: "Bjørn Mork" <bjorn@mork.no>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "netdev\@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-usb\@vger.kernel.org" <linux-usb@vger.kernel.org>,
Alexey Orishko <alexey.orishko@gmail.com>,
Oliver Neukum <oliver@neukum.org>,
Enrico Mioso <mrkiko.rs@gmail.com>,
Lars Melin <larsm17@gmail.com>, Peter Stuge <peter@stuge.se>,
Greg Suarez <gsuarez@smithmicro.com>
Subject: Re: [PATCH v2 net-next 3/8] net: cdc_ncm: inform usbnet when rx buffers are reduced
Date: Fri, 30 May 2014 15:39:14 +0200 [thread overview]
Message-ID: <87mwdz8jy5.fsf@nemi.mork.no> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D17250700@AcuExch.aculab.com> (David Laight's message of "Fri, 30 May 2014 12:42:29 +0000")
David Laight <David.Laight@ACULAB.COM> writes:
> From: Bjørn Mork
> ...
>> > Since you are now copying the data out of the URB's skb before
>> > passing the ethernet packet upstream, is there ever any real
>> > requirement to use a small rx_max? or ever change rx_max?
>>
>> Yes. usbnet doesn't currently recycle skbs. Continuously allocating 32
>> kB skbs (or even 64 kB truesize, which is the current cdc_ncm worst
>> case) on memory constrained hosts is bound to fail eventually.
>
> Getting usbnet to recycle skb shouldn't be too hard - and will
> be an immediate gain for most of the drivers.
Yes. This is one of those problems that really isn't that hard to
solve. Until you start hitting all the corner cases... But I'm sure it
is doable.
Anyway, it is not going to be part of this patch series, which is merely
touching the cdc_ncm minidriver within the existing usbnet framework.
Bjørn
next prev parent reply other threads:[~2014-05-30 13:39 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-30 7:31 [PATCH v2 net-next 0/8] cdc_ncm: fixes and conversion to sysfs API Bjørn Mork
2014-05-30 7:31 ` [PATCH v2 net-next 1/8] net: cdc_ncm: reduce skb truesize in rx path Bjørn Mork
[not found] ` <1401435070-26721-1-git-send-email-bjorn-yOkvZcmFvRU@public.gmane.org>
2014-05-30 7:31 ` [PATCH v2 net-next 2/8] net: cdc_ncm: always reallocate tx_curr_skb when tx_max increases Bjørn Mork
2014-05-30 7:31 ` [PATCH v2 net-next 4/8] net: cdc_ncm: use sysfs for rx/tx aggregation tuning Bjørn Mork
2014-05-30 7:31 ` [PATCH v2 net-next 3/8] net: cdc_ncm: inform usbnet when rx buffers are reduced Bjørn Mork
[not found] ` <1401435070-26721-4-git-send-email-bjorn-yOkvZcmFvRU@public.gmane.org>
2014-05-30 9:18 ` David Laight
2014-05-30 11:39 ` Bjørn Mork
2014-05-30 12:39 ` David Laight
2014-05-30 13:35 ` Bjørn Mork
[not found] ` <87d2eva41t.fsf-lbf33ChDnrE/G1V5fR+Y7Q@public.gmane.org>
2014-05-30 12:42 ` David Laight
2014-05-30 13:39 ` Bjørn Mork [this message]
2014-05-30 7:31 ` [PATCH v2 net-next 5/8] net: cdc_ncm: drop ethtool coalesce support Bjørn Mork
2014-05-30 7:31 ` [PATCH v2 net-next 6/8] net: cdc_ncm: export NCM Transfer Block (NTB) parameters Bjørn Mork
2014-05-30 7:31 ` [PATCH v2 net-next 7/8] net: cdc_ncm: allow tuning min_tx_pkt Bjørn Mork
2014-05-30 7:31 ` [PATCH v2 net-next 8/8] net: cdc_ncm: document the sysfs API Bjørn Mork
2014-06-02 23:02 ` [PATCH v2 net-next 0/8] cdc_ncm: fixes and conversion to " David Miller
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