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Thu, 24 Mar 2022 06:44:32 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzgNNq102RyReP+3YYUndcCIRZi3ibyWkwWqmt/SzTb2UQ2bOtzGwlYr0ThA8yYkTC7SSx77g== X-Received: by 2002:a05:600c:3c9b:b0:380:be98:6204 with SMTP id bg27-20020a05600c3c9b00b00380be986204mr14216898wmb.121.1648129472548; Thu, 24 Mar 2022 06:44:32 -0700 (PDT) Received: from [192.168.0.36] ([78.17.178.139]) by smtp.gmail.com with ESMTPSA id k5-20020a5d66c5000000b00203fd25f4ecsm2605299wrw.16.2022.03.24.06.44.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 24 Mar 2022 06:44:31 -0700 (PDT) Message-ID: <6c29b50d-973d-8be1-369a-ca78a13b9655@redhat.com> Date: Thu, 24 Mar 2022 13:44:30 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 To: "Zhang, Qi Z" , "Wu, Wenjun1" , "dev@dpdk.org" , "Yang, Qiming" Cc: "Van Haaren, Harry" , "Su, Simei" , Luca Boccassi , Christian Ehrhardt References: <20220222062612.335622-1-wenjun1.wu@intel.com> <20220228073607.2249410-1-wenjun1.wu@intel.com> <3da8efff430e43808657c353c748ea9d@intel.com> <4d81601b-6aa5-3746-a888-7a290e071997@redhat.com> <87ea19805e604ca5b85366cf11028a09@intel.com> From: Kevin Traynor Subject: Re: [PATCH v4] net/ice: improve performance of RX timestamp offload In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ktraynor@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On 24/03/2022 13:05, Zhang, Qi Z wrote: > > >> -----Original Message----- >> From: Kevin Traynor >> Sent: Thursday, March 24, 2022 8:18 PM >> To: Zhang, Qi Z ; Wu, Wenjun1 >> ; dev@dpdk.org; Yang, Qiming >> >> Cc: Van Haaren, Harry ; Su, Simei >> ; Luca Boccassi ; Christian Ehrhardt >> >> Subject: Re: [PATCH v4] net/ice: improve performance of RX timestamp >> offload >> >> On 24/03/2022 11:51, Zhang, Qi Z wrote: >>> >>> >>>> -----Original Message----- >>>> From: Kevin Traynor >>>> Sent: Thursday, March 24, 2022 7:17 PM >>>> To: Zhang, Qi Z ; Wu, Wenjun1 >>>> ; dev@dpdk.org; Yang, Qiming >>>> >>>> Cc: Van Haaren, Harry ; Su, Simei >>>> ; Luca Boccassi ; Christian >>>> Ehrhardt >>>> Subject: Re: [PATCH v4] net/ice: improve performance of RX timestamp >>>> offload >>>> >>>> On 24/03/2022 09:09, Zhang, Qi Z wrote: >>>>> >>>>> >>>>>> -----Original Message----- >>>>>> From: Wu, Wenjun1 >>>>>> Sent: Monday, February 28, 2022 3:36 PM >>>>>> To: dev@dpdk.org; Zhang, Qi Z ; Yang, Qiming >>>>>> >>>>>> Cc: Van Haaren, Harry ; Su, Simei >>>>>> ; Wu, Wenjun1 >>>>>> Subject: [PATCH v4] net/ice: improve performance of RX timestamp >>>>>> offload >>>>>> >>>>>> Previously, each time a burst of packets is received, SW reads HW >>>>>> register and assembles it and the timestamp from descriptor >>>>>> together to get the complete 64 bits timestamp. >>>>>> >>>>>> This patch optimizes the algorithm. The SW only needs to check the >>>>>> monotonicity of the low 32bits timestamp to avoid crossing borders. >>>>>> Each time before SW receives a burst of packets, it should check >>>>>> the time difference between current time and last update time to >>>>>> avoid the low 32 bits timestamp cycling twice. >>>>>> >>>>>> Signed-off-by: Wenjun Wu >>>>> >>>>> Added cc stable >>>>> >>>> >>>> Hi Qi. The DPDK documentation has guidance about what should be >>>> backported to LTS [0] and distinguishes between fixes and performance >>>> improvements. Please try and stick with this when applying patches or >>>> let LTS maintainers know if there is a debatable case. >>> >>> Thanks for the comments >>> Yes, actually this is about a 50% ~ 70% performance improvement, which >>> maybe critical for some performance sensitive use cases.(e.g. network >>> forensics) So I'd like to defend with below case >>> >>> An existing feature in LTS is not usable as intended without it. >>> >> >> If that is the case, then I think the commitlog should be re-written. It just >> talks about the code changes, there's nothing about an impact to an existing >> use case that was unusuable and is now fixed. > > OK, I updated with below commit log in dpdk-next-net-intel. > Kevin , Wenjun, let me know if anything I missed. > > Previously, each time a burst of packets is received, SW reads HW > register and assembles it and the timestamp from descriptor together to > get the complete 64 bits timestamp. > > This patch optimizes the algorithm. The SW only needs to check the > monotonicity of the low 32bits timestamp to avoid crossing borders. > Each time before SW receives a burst of packets, it should check the > time difference between current time and last update time to avoid > the low 32 bits timestamp cycling twice. > > The patch proved a 50% ~ 70% single core performance improvement on a > main stream Xeon server, and it is necessary to be backport to LTS release, > as this fix the performance gap for some use cases. > The comment about backport to LTS can be removed. That is an operational comment, so not really relevant to a future reader trying to understand the commit. thanks, Kevin. > Thanks > Qi > >> >>> Thanks >>> Qi >>> >>>> >>>> thanks, >>>> Kevin. >>>> >>>> [0] >>>> http://doc.dpdk.org/guides-21.11/contributing/stable.html#what-change >>>> s- >>>> should-be-backported >>> >>>> >>>>> Acked-by: Qi Zhang >>>>> >>>>> Applied to dpdk-next-net-intel. >>>>> >>>>> Thanks >>>>> Qi >>>>> >>>> >>> >