From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: Low performance Intel 10GE NIC (3.2.10) on 2.6.38 Kernel
Date: Thu, 14 Apr 2011 18:45:24 +0200
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Cc: Wei Gu <wei.gu@ericsson.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	netdev <netdev@vger.kernel.org>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel.com>
To: Alexander Duyck <alexander.h.duyck@intel.com>
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Le jeudi 14 avril 2011 =C3=A0 09:42 -0700, Alexander Duyck a =C3=A9crit=
 :

> The only issue I have found so far with the ixgbe driver is the fact=20
> that apparently rx_no_buffer_count is apparently always going to be 0=
 on=20
> 82599, and that isn't so much a driver problem as a hardware limitati=
on=20
> as the HW counter was removed in 82599.  However since the hardware w=
as=20
> capable of going faster on the other kernels what this likely means i=
s=20
> that the rx_missed_errors are due to the driver not providing Rx buff=
ers=20
> fast enough.
>=20
> I'm doing some more digging into this now.  One thought that occurred=
 to=20
> me is that if the patch you mention is having some sort of effect thi=
s=20
> could be a sign of perhaps a kernel timer or scheduling problem.

We could try to instrument the delay betwen hardware IRQ and napi
handler called.