From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: (Lack of) specification for RX n-tuple filtering Date: Wed, 08 Dec 2010 19:14:04 +0000 Message-ID: <1291835644.2560.52.camel@bwh-desktop> References: <1279832544.2104.63.camel@achroite.uk.solarflarecom.com> <4C48BD1A.4060409@chelsio.com> <1283870637.2270.10.camel@achroite.uk.solarflarecom.com> <1291825443.31064.193.camel@lb-tlvb-vladz> <1291828940.2560.17.camel@bwh-desktop> <4CFFD470.5090407@chelsio.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Vladislav Zolotarov , Peter Waskiewicz , "netdev@vger.kernel.org" , David Miller To: Dimitris Michailidis Return-path: Received: from mail.solarflare.com ([216.237.3.220]:49499 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755553Ab0LHTOH (ORCPT ); Wed, 8 Dec 2010 14:14:07 -0500 In-Reply-To: <4CFFD470.5090407@chelsio.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2010-12-08 at 10:54 -0800, Dimitris Michailidis wrote: > Ben Hutchings wrote: > > On Wed, 2010-12-08 at 18:24 +0200, Vladislav Zolotarov wrote: > >>>> It's a bit worse than that. Currently one can only append filters, not > >>>> insert at a given position, as ethtool_rx_ntuple doesn't have an index > >>>> field. For devices that use TCAMs, where position matters, it's quite an > >>>> obstacle. It also means one cannot modify an existing filter by specifying > >>>> a new filter for the same index. > >>> It looks like drivers for devices that use TCAMs should implement the > >>> RXNFC interface instead. > >>> > >> Ben, from ethtool manpage it sounds like RXNFC option defines the way > >> the RSS hash should be calculated, while SRXNTUPLE is meant to control > >> the destination Rx queue for a stream specified by a filter/filters. > > > > By 'RXNFC interface' I mean ETHTOOL_{G,S}RXCLS* and not > > ETHTOOL_{G,S}RXFH which wrongly share (part of) the same structure.. > > > >> The > >> semantics for a specification of the steam is also quite different. For > >> instance, how do u define a rule to drop all packets with source IP > >> address 192.168.10.200 by means of RXNFC? > > > > Something like this, I think: > > > > struct ethtool_rxnfc insert_rule = { > > .cmd = ETHTOOL_SRXCLSRLINS, > > .flow_type = IP_USER_SPEC, > > .fs = { > > .flow_type = IP_USER_SPEC, > > .h_u.usr_ip4_spec = { > > .ip4src = inet_aton("192.168.10.200"), > > .ip_ver = ETH_RX_NFC_IP4 > > }, > > .m_u.usr_ip4_spec = { > > .ip4dst = 0xffffffff, > > .l4_4_bytes = 0xffffffff, > > .tos = 0xff, > > .proto = 0xff > > }, > > .ring_cookie = RX_CLS_FLOW_DISC, > > .location = 0, > > } > > }; > > I think the mask would be 0 for don't care fields and 1 for care, so > > .m_u.usr_ip4_spec.ip4src = htonl(0xffffffff) > .m_u.usr_ip4_spec.ip4dst = htonl(0) > etc That is definitely the opposite of what ixgbe and sfc do for ethtool_ntuple_rx_flow_spec, and I believe it is the opposite of what niu does for ethtool_rx_flow_spec. [...] > >> It's also unclear what is the relation between RXNFC and SRXNTUPLE. The > >> last in general may override the decision made based on the hash result. > >> So, it sounds like applying rules of SRXNTUPLE should come before > >> applying the RSS logic and only if there was no match RSS should be > >> applied to that frame. Do I get it right? > > > > That's right. > > It can be more involved than this. Our HW allows a rule to select a > different part of the RSS table so you get a filter hit and still do RSS > afterwards if you want. Current ethtool interfaces do not support this, > basically it would be a different action for either SRXNTUPLE or SRXCLSRLINS. So does the rule specify an offset added to the output of the RSS hash and indirection table, or can it also select a different indirection table? Our current hardware also has a filter flag for the former behaviour... There are still plenty of bits to spare in 'action' and 'ring_cookie' so perhaps we could define a flag for this? Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.