From: Larry Finger <Larry.Finger@lwfinger.net>
To: Johannes Stezenbach <js@sig21.net>
Cc: Igor Plyatov <plyatov@gmail.com>, linux-wireless@vger.kernel.org
Subject: Re: rt2800usb: page allocation failure
Date: Tue, 12 Apr 2011 20:38:04 -0500 [thread overview]
Message-ID: <4DA4FE7C.8070807@lwfinger.net> (raw)
In-Reply-To: <20110412212236.GA8877@sig21.net>
On 04/12/2011 04:22 PM, Johannes Stezenbach wrote:
>
> I don't think the allocation uses the MTU, rather rt2x00queue_alloc_rxskb()
> uses some hw specific constants. No idea if these can be reduced,
> but multi-page GFP_ATOMIC allocations can easily fail.
That is likely. Those hw specific constants add up to 40 bytes, thus the major
part is actual buffer. That is set at 3840 bytes, thus I don't understand why
the request was order 1.
> However, I'm not sure why an 8kB allocation fails if the oom dump
> says 2*8kB are available. I guess it has something to do with
> the GFP_ATOMIC.
My guess is that those 8kB buffers were freed between the failure and the dump.
The actual allocation is done by dev_alloc_skb() through a call to __alloc_skb()
with GFP_ATOMIC, thus we have no chance to change this.
@Igor: The buffer size is set in the define for AGGREGATION_SIZE located in
drivers/net/wireless/rt2x00/rt2x00queue.h. Reducing that will cut the buffer
size request, but might not help the problem.
Larry
next prev parent reply other threads:[~2011-04-13 1:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-12 15:38 rt2800usb: page allocation failure Igor Plyatov
2011-04-12 18:00 ` Larry Finger
2011-04-12 21:22 ` Johannes Stezenbach
2011-04-13 1:38 ` Larry Finger [this message]
2011-04-13 7:54 ` Helmut Schaa
2011-04-13 7:55 ` Johannes Stezenbach
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