From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Kleine-Budde Subject: Re: command ip -details -statistics link show wlan0 Date: Thu, 16 May 2013 17:37:53 +0200 Message-ID: <5194FD51.1030803@pengutronix.de> References: <5194846B.1070307@grandegger.com> <5194F46D.4060905@grandegger.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="----enig2GBXXKDFFJKXLRAHBNANG" Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:50417 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751967Ab3EPPiA (ORCPT ); Thu, 16 May 2013 11:38:00 -0400 In-Reply-To: Sender: linux-can-owner@vger.kernel.org List-ID: To: Ernast Sevo Cc: Wolfgang Grandegger , "linux-can@vger.kernel.org" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2GBXXKDFFJKXLRAHBNANG Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable On 05/16/2013 05:32 PM, Ernast Sevo wrote: >> Well, not sure if the hardware realizes any packet lost. This typicall= y >> happens when the software does not empty the hardware buffers quickly >> enough? What hardware are you using? MCP251x? > Yes I am using MCP2515. I am getting a couple of rx buffer overflow err= ors > so I was wondering how these errors corresponded to packet loss, > whether this is a 1:1 relationship or 1:N relationship (if i am > interpretting Marc's post > correctly should I assume 1:1 for best case and 1:N for worst case? ). Yes, exactly. > Essentially I am trying to determine at what speed i can have stuff > coming in before > I start losing packets for any reason. I know how to account packets > lost in userspace > and packets lost by the driver (which you mentioned above) and now I > am trying to > account for packets lost at the hardware level. Knowing how these rx bu= ffer > overflow/overrun errors correspond to packet loss would help make my > data more accurate and reliable. If you don't get any dropped frames reported via SO_RXQ_OVFL (see Wolfgang mail) you can be sure they are lost at the hardware level. I suggest don't use the mcp251x, it's really slow and puts heavy load on the machine. However there might be some knobs to tune in your SPI controller/driver. Marc --=20 Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | ------enig2GBXXKDFFJKXLRAHBNANG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEUEARECAAYFAlGU/VUACgkQjTAFq1RaXHMViwCYjh6N7aQfk3rtqE7ZhpjILsGD PQCfXj4TCCMg7Z5T51hMcy0B3R8anIA= =5Aqr -----END PGP SIGNATURE----- ------enig2GBXXKDFFJKXLRAHBNANG--