>-----Original Message----- >From: John Fastabend [mailto:john.fastab...@gmail.com] >Sent: Thursday, November 10, 2016 9:38 PM >To: Jiri Pirko <j...@resnulli.us>; netdev@vger.kernel.org >Cc: da...@davemloft.net; Yotam Gigi <yot...@mellanox.com>; Ido Schimmel ><ido...@mellanox.com>; Elad Raz <el...@mellanox.com>; Nogah Frankel ><nog...@mellanox.com>; Or Gerlitz <ogerl...@mellanox.com>; >j...@mojatatu.com; geert+rene...@glider.be; step...@networkplumber.org; >xiyou.wangc...@gmail.com; li...@roeck-us.net; ro...@cumulusnetworks.com >Subject: Re: [patch net-next 5/8] Introduce sample tc action > >On 16-11-10 11:35 AM, John Fastabend wrote: >> On 16-11-10 03:23 AM, Jiri Pirko wrote: >>> From: Yotam Gigi <yot...@mellanox.com> >>> >>> This action allow the user to sample traffic matched by tc classifier. >>> The sampling consists of choosing packets randomly, truncating them, >>> adding some informative metadata regarding the interface and the original >>> packet size and mark them with specific mark, to allow further tc rules to >>> match and process. The marked sample packets are then injected into the >>> device ingress qdisc using netif_receive_skb. >>> >>> The packets metadata is packed using the ife encapsulation protocol, and >>> the outer packet's ethernet dest, source and eth_type, along with the >>> rate, mark and the optional truncation size can be configured from >>> userspace. >>> >>> Example: >>> To sample ingress traffic from interface eth1, and redirect the sampled >>> the sampled packets to interface dummy0, one may use the commands: >>> >>> tc qdisc add dev eth1 handle ffff: ingress >>> >>> tc filter add dev eth1 parent ffff: \ >>> matchall action sample rate 12 mark 17 >>> >>> tc filter add parent ffff: dev eth1 protocol all \ >>> u32 match mark 17 0xff \ >>> action mirred egress redirect dev dummy0 >>> >>> Where the first command adds an ingress qdisc and the second starts >>> sampling every 12'th packet on dev eth1 and marks the sampled packets with >>> 17. The third command catches the sampled packets, which are marked with >>> 17, and redirects them to dev dummy0. >> >> The sampling algorithm was not randomized based on the above commit >> log? It really needs to be for all the reasons Roopa mentioned earlier. >> Did I miss some email on why it didn't get implemented? >> >> Also there was an indication the already is actually implemented >> correctly so don't we need the hw/sw to behave the same. The whole >> argument about sw/hw parity, etc. > >sorry bit of a typo there corrected 2nd paragraph here... > >Also there was an indication the hardware is already implemented \ >correctly so don't we need the hw/sw to behave the same. The argument >about sw/hw parity, etc.
Our hardware currently does not support sampling with random behavior, so we did implement it in software too. But, the API is extensible and it is possible to add a random keyword to the tc action to allow random sampling. In that case, the keyword will be implemented in sw only and our driver will fail offloading it. > >> >>> >>> Signed-off-by: Yotam Gigi <yot...@mellanox.com> >>> Signed-off-by: Jiri Pirko <j...@mellanox.com> >>> --- >>
