From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olivier MATZ Subject: Re: [PATCH] i40e: Use one bit flag for all hardware detected RX packet errors Date: Wed, 26 Nov 2014 15:12:09 +0100 Message-ID: <5475DFB9.7060609@6wind.com> References: <1416982032-28519-1-git-send-email-helin.zhang@intel.com> <2601191342CEEE43887BDE71AB977258213BA7CA@IRSMSX105.ger.corp.intel.com> <5475B7EE.4020400@6wind.com> <2601191342CEEE43887BDE71AB977258213BA8CB@IRSMSX105.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: "Ananyev, Konstantin" , "Zhang, Helin" , "dev-VfR2kkLFssw@public.gmane.org" Return-path: In-Reply-To: <2601191342CEEE43887BDE71AB977258213BA8CB-kPTMFJFq+rEu0RiL9chJVbfspsVTdybXVpNB7YpNyf8@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" Hi Konstantin, On 11/26/2014 02:38 PM, Ananyev, Konstantin wrote: >>> Probably I didn't explain myself clear enough, sorry. >>> I didn't suggest to get rid of setting bits that indicate L3/L4 checksum errors: >>> PKT_RX_IP_CKSUM_BAD, PKT_RX_L4_CKSUM_BAD, PKT_RX_EIP_CKSUM_BAD. >>> I think these flags should be set as before. >>> >>> I was talking only about collapsing only these 4 RX error flags into one: >>> >>> #define PKT_RX_OVERSIZE (0ULL << 0) /**< Num of desc of an RX pkt oversize. */ >>> #define PKT_RX_HBUF_OVERFLOW (0ULL << 0) /**< Header buffer overflow. */ >>> #define PKT_RX_RECIP_ERR (0ULL << 0) /**< Hardware processing error. */ >>> #define PKT_RX_MAC_ERR (0ULL << 0) /**< MAC error. */ >>> >>> From my point of view the difference of these 2 groups are: >>> First - HW was able to receive whole packet without a problem, but L3/L4 checksum check failed. >>> >>> Second - HW was not able to receive whole packet properly by whatever reason. >>> From upper layer SW perspective - there it probably makes little difference, what caused it, >>> as most likely SW has to throw away erroneous packet. >>> And for debugging purposes, we can add PMD_LOG(DEBUG, ...) that would print what exactly HW error happened. >> >> I agree with Konstantin that there are 2 different cases: >> >> a) the packet is properly received by the hardware, but has a bad >> checksum (or another protocol error, for instance an invalid ip len, >> a ip_version == 8 :)) >> >> in this case, it is useful to the application to have the mbuf with >> the data + an error flag. Then using a tcpdump-like tool could help >> to debug what is the cause of the error and what equipment generates >> a bad packet. >> >> b) the packet is not properly received by the hardware. In this case >> the data is invalid in the mbuf and not useable by the application. >> I suggest to only have a stats counter in this case, as receiving the >> mbuf is cpu time consuming and the only thing the application can do >> is to drop the packet. > > So for b) you suggest to drop the packet straight in PMD RX function? > Something like: > if (unlikely(error_bits & ...)) { > PMD_LOG(DEBUG, ...); > rte_pktmbuf_free(mb); > } > ? Yes > That's probably a bit too radical. > Yes, mbuf doesn't contain the whole packet, but it may contain at least part of it, let say in case of 'packet oversize'. > So for debugging purposes the user may still like to examine the mbuf contents. As soon as there is some exploitable data in the mbuf, I agree it can be transfered to the application (ex: bad header, bad len, bad checksum...). But if the hardware is not able to provide any exploitable data, it looks a bit overkill to give an mbuf with an error flag. But grouping the flags as you suggest is already a good clean-up to me, I don't want to be more catholic than the Pope ;) Regards, Olivier