From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [patch net-next v4 0/4] return offloaded stats as default and expose original sw stats Date: Sat, 18 Jun 2016 10:00:00 +0200 Message-ID: <20160618080000.GA1989@nanopsycho.orion> References: <1466066237-7719-1-git-send-email-jiri@resnulli.us> <20160616.172632.1759391103978744570.davem@davemloft.net> <20160617082411.GA1981@nanopsycho.orion> <20160617140512.GB1981@nanopsycho.orion> <57640F2A.7090003@mojatatu.com> <9f8e85ac-3e96-257e-cf7f-e7e793d41cf4@cumulusnetworks.com> <20160617154243.GD1981@nanopsycho.orion> <57642F76.6090403@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Ahern , Jamal Hadi Salim , David Miller , netdev@vger.kernel.org, nogahf@mellanox.com, idosch@mellanox.com, eladr@mellanox.com, yotamg@mellanox.com, ogerlitz@mellanox.com, roopa@cumulusnetworks.com, nikolay@cumulusnetworks.com, linville@tuxdriver.com, tgraf@suug.ch, gospo@cumulusnetworks.com, sfeldma@gmail.com, sd@queasysnail.net, eranbe@mellanox.com, ast@plumgrid.com, edumazet@google.com, hannes@stressinduktion.org To: Florian Fainelli Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:33508 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750868AbcFRIAD (ORCPT ); Sat, 18 Jun 2016 04:00:03 -0400 Received: by mail-wm0-f66.google.com with SMTP id r201so2564946wme.0 for ; Sat, 18 Jun 2016 01:00:03 -0700 (PDT) Content-Disposition: inline In-Reply-To: <57642F76.6090403@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Fri, Jun 17, 2016 at 07:12:22PM CEST, f.fainelli@gmail.com wrote: >On 06/17/2016 08:42 AM, Jiri Pirko wrote: >> Fri, Jun 17, 2016 at 05:35:53PM CEST, dsa@cumulusnetworks.com wrote: >>> On 6/17/16 8:54 AM, Jamal Hadi Salim wrote: >>>> On 16-06-17 10:05 AM, Jiri Pirko wrote: >>>>> Fri, Jun 17, 2016 at 03:48:35PM CEST, dsa@cumulusnetworks.com wrote: >>>>>> On 6/17/16 2:24 AM, Jiri Pirko wrote: >>>>>>> >>>> >>>>> >>>>> That is problematic. Existing apps depend on rtnetlink stats. But if we >>>>> don't count offloaded forwarded packets, the apps don't see anything. >>>>> Therefore I believe that this patchset approach is better. The existing >>>>> apps continue to work and future apps can use newly introduces sw_stats >>>>> to query slowpath traffic. Makes sense to me. >>>>> >>>> >>>> I agree with Jiri. It is a bad idea to depend on ethtool for any of >>>> this stuff. Is there a way we can tag netlink stats instead >>>> to indicate they are hardware or software? >>> >>> Right, old API but the key here is that low level h/w stats are returned by a >>> different API. >>> >>> By default ip, ifconfig, snmpd, etc all continue to get traditional S/W stats >>> - counters as seen by the CPU. >> >> Yep. And I believe that for offloaded forwarding, this tools should see >> hw counters, as they show what is going on in real. > >If your NIC is offloading packets today, these tools typically won't see >these stats, but ethtool -S likely will report what is going on under >the hood. > >Do we actually need to tell apart SW maintained from HW maintained >stats, or at the end all that matters is just, as DaveM pointed out, >getting the information, and in the case of an Ethernet switch, return >HW stats by default and supplement with SW stats whenever we have them, >all in the same namespace? I believe it is valuable for user to know stats for slow path (non-forwarded by ASIC). Also, it's just another rtnl attr. Easy.