Date: Thu, 6 Nov 2014 12:58:30 -0500 From: Ryan Stone <rysto32@gmail.com> To: Adrian Chadd <adrian@freebsd.org> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "Alexander V. Chernikov" <melifaro@freebsd.org> Subject: Re: svn commit: r273112 - head/sys/dev/ixgbe Message-ID: <CAFMmRNwT-FBU=WGRhuut8COdMwDmLuwpBGCirJzYHMDx0qv7BQ@mail.gmail.com> In-Reply-To: <CAJ-VmokhhBiJ%2Buj8yEsfGj4i6FsaBFiZDdYhtFnHgJC3GAokZQ@mail.gmail.com> References: <201410150122.s9F1Mudu083306@svn.freebsd.org> <545B55FA.6070408@FreeBSD.org> <CAJ-VmokhhBiJ%2Buj8yEsfGj4i6FsaBFiZDdYhtFnHgJC3GAokZQ@mail.gmail.com>
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On Thu, Nov 6, 2014 at 12:21 PM, Adrian Chadd <adrian@freebsd.org> wrote:
> Hm, are there any other hardware counters that we can use to see what
> was dropped?
On the 82599 and later you need to configure the RQSMR register to map
queue pools to indices and then the QPRDC[i] register will contain the
number of drops.
Note that the 82598 doesn't support the DROPEN bit in the SRRCTL
register. There is a separate DROPEN register on the 82598, but I
have the following worrisome comment in my version of ixgbe:
if (hw->mac.type == ixgbe_mac_82598EB) {
/*
* The DROPEN register is intended to allow us to immediately
* drop packets that cannot be DMA'ed to memory right away to
* avoid head-of-line blocking. However we have observed that
* enabling this functionality can lead to situations where a
* queue will drop every packet destined for it silently, so
* we instead accept the HOL blocking and disable the immediate
* dropping
*/
IXGBE_WRITE_REG(&adapter->hw, IXGBE_DROPEN, 0);
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