Return-path: Received: from mail2.candelatech.com ([208.74.158.173]:53842 "EHLO mail2.candelatech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752570AbaHHQLh (ORCPT ); Fri, 8 Aug 2014 12:11:37 -0400 Message-ID: <53E4F6B8.50009@candelatech.com> (sfid-20140808_181141_131840_EA852436) Date: Fri, 08 Aug 2014 09:11:36 -0700 From: Ben Greear MIME-Version: 1.0 To: Dave Taht CC: Kalle Valo , "linux-wireless@vger.kernel.org" , ath10k Subject: Re: Reporting firmware stats to ethtool References: <53E3F65D.8080102@candelatech.com> <87wqajz6yg.fsf@kamboji.qca.qualcomm.com> <53E4EFCB.5090501@candelatech.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 08/08/2014 08:55 AM, Dave Taht wrote: > On Fri, Aug 8, 2014 at 8:42 AM, Ben Greear wrote: >> On 08/08/2014 02:06 AM, Kalle Valo wrote: >>> Ben Greear writes: >>> >>>> I'm working on a patch to report the stats seen in debugfs/...ath10k/fw_stats >>>> as ethtool stats, somewhat similar to how ath9k does it. >>>> >>>> I notice that my user-space tool is reporting huge numbers because >>>> the stats are reset to zero when firmware restarts, and so my tool >>>> thinks the stats wrapped. >>>> >>>> I can fix my tool easily enough, but I first wanted to see if >>>> anyone had strong feelings about keeping the stats from resetting >>>> to zero by storing history and calculating diffs in the driver. >>>> >>>> I think my preference is to punt this to user-space, but if >>>> someone feels otherwise, please let me know sooner than later. >>> >>> I also prefer to have this in user space, but how does user space know >>> when the stats have been zeroed? >> >> Poll often enough that it cannot increment more than 2 billion (or other large number) >> between polls, and then if polled value is less than previous (and difference is > 2 billion), >> we know we had a reset and not a wrap. > > I do kind of prefer 64 bit counters in the general case. Nuke it from > orbit, it's the only way to be sure. It's 64-bit to user-space, but that means nothing because firmware uses 32-bit (or even 16 bit in some cases, probably) internally. A great deal of counters are the same, so be very careful when trying to keep long term counters grabbed from firmware/drivers/hardware. And, stations come and go when you re-associate, so all sorts of wifi counters reset themselves all the time... Thanks, Ben > >> User-space stats will not be perfect in the case of firmware resets, or resets >> after the 'large number', but nothing is going to make it perfect, and in >> practice, this seems good enough. >> >> Thanks, >> Ben >> >> -- >> Ben Greear >> Candela Technologies Inc http://www.candelatech.com >> >> >> _______________________________________________ >> ath10k mailing list >> ath10k@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/ath10k > > > -- Ben Greear Candela Technologies Inc http://www.candelatech.com