netdev - RE: [PATCH 1/2] igb: Implement reading of reg RQDPC (Receive Queue Drop Packet Count)

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Date:	Thu, 7 May 2009 21:19:35 +0200 (CEST)
From:	Jesper Dangaard Brouer <hawk@...u.dk>
To:	"Williams, Mitch A" <mitch.a.williams@...el.com>
Cc:	Jesper Dangaard Brouer <hawk@...x.dk>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"David S. Miller" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"e1000-devel@...ts.sourceforge.net" 
	<e1000-devel@...ts.sourceforge.net>,
	"Ronciak, John" <john.ronciak@...el.com>,
	"Waskiewicz Jr, Peter P" <peter.p.waskiewicz.jr@...el.com>
Subject: RE: [PATCH 1/2] igb: Implement reading of reg RQDPC (Receive Queue
 Drop Packet Count)


On Thu, 7 May 2009, Williams, Mitch A wrote:

>> Implement reading the per queue drop stats register
>> RQDPC (Receive Queue Drop Packet Count).  It counts the number of
>> packets dropped by a queue due to lack of descriptors available.
>>
>> Notice RQDPC (Receive Queue Drop Packet Count) stats only gets
>> incremented, if the DROP_EN bit it set (in the SRRCTL register
>> for that queue). If DROP_EN bit is NOT set, then the some what
>> equivalent count is stored in RNBC (not per queue basis).
>>
>> The RQDPC register is only 12 bit, thus the precision might
>> suffer due to overrun in-between the watchdog polling interval.
>
> NAK.  82575 doesn't have RQDPC registers.  You need to check
> which part you're running on before you read those registers.

Strange, I though the RQDPC register were compatible with the 82575 
registers, as the 82576 datasheet states:

Quote 82576 DS:
   Note: In order to keep compatibility with the 82575, for queues 0-3,
   these registers are aliased to addresses 0x2830, 0x2930, 0x2A30 & 0x2B30
   respectively.

And I do take care of reading the aliased adresses in the RQDPC define 
statement for queues 0-3.

Well, I unfortunatly done have a 82575 based NIC anymore (as my prototype 
NIC from Hotlava Systems Inc. just died).  And I don't have the 82575 
datasheet, it does not seem to be available!?

Any chance I could get the 82575 register datasheet?


> Other than that, this looks OK to me.

That sounds good :-)

ps. It will be monday or tuesday before I have time to repost the 
patchset.

Cheers,
   Jesper Brouer

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