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Mon, 06 Feb 2023 07:06:36 -0800 (PST) X-Google-Smtp-Source: AK7set9waaEzMV/XH47SkmjDncgCmT598oCI1KYWtdEWv7tSrw5Lk6J7W1xR1CPMz+eDsqaGrNXlxL7jgAiwRIAzo5g= X-Received: by 2002:a17:90b:e17:b0:230:36c1:fde6 with SMTP id ge23-20020a17090b0e1700b0023036c1fde6mr3307090pjb.83.1675695996504; Mon, 06 Feb 2023 07:06:36 -0800 (PST) MIME-Version: 1.0 References: <20221123102612.1688865-1-rjarry@redhat.com> <20230202134329.539625-1-rjarry@redhat.com> <20230202134329.539625-5-rjarry@redhat.com> <CAJFAV8x68_uiHhrWJLM8y45HLTWEVLM+SXRqRXs3gSC7=VVTJA@mail.gmail.com> <CQBD1740I7MF.27AX8WCBNT5OF@ringo> In-Reply-To: <CQBD1740I7MF.27AX8WCBNT5OF@ringo> From: David Marchand <david.marchand@redhat.com> Date: Mon, 6 Feb 2023 16:06:25 +0100 Message-ID: <CAJFAV8zT+Za2Asr1AP7UePRLrh-yUbWGWM9VHNY80gjPiqXa4g@mail.gmail.com> Subject: Re: [PATCH v8 4/5] app/testpmd: report lcore usage To: Robin Jarry <rjarry@redhat.com>, Aman Singh <aman.deep.singh@intel.com>, Yuying Zhang <yuying.zhang@intel.com> Cc: dev@dpdk.org, =?UTF-8?Q?Morten_Br=C3=B8rup?= <mb@smartsharesystems.com>, Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>, Kevin Laatz <kevin.laatz@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions <dev.dpdk.org> List-Unsubscribe: <https://mails.dpdk.org/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://mails.dpdk.org/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <https://mails.dpdk.org/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> Errors-To: dev-bounces@dpdk.org On Mon, Feb 6, 2023 at 10:08 AM Robin Jarry <rjarry@redhat.com> wrote: > > David Marchand, Feb 06, 2023 at 09:58: > > I have been playing a bit with this series with two lcores, each one > > polling a net/null port. > > At first it looked good, but then I started to have one idle lcore, by > > asking net/null not to receive anything. > > > > $ build-clang/app/dpdk-testpmd -c 7 --no-huge -m 40 -a 0:0.0 --vdev > > net_null1,no-rx=1 --vdev net_null2 -- --no-mlockall > > --total-num-mbufs=2048 -ia --record-core-cycles --nb-cores=2 > > > > One thing that struck me is that an idle lcore was always showing less > > "total_cycles" than a busy one. > > The more time testpmd was running, the bigger the divergence between > > lcores would be. > > > > Re-reading the API, it is unclear to me (which is the reason for my > > comments on patch 2). > > Let's first sort out my patch 2 comments and we may revisit this patch > > 4 implementation afterwards (as I think we are not accounting some > > mainloop cycles with current implementation). > > Indeed, we are not accounting for all cycles. Only the cycles spent in > the packet_fwd_t functions. This was already the case before my series > I only added the busy cycles accounting. "busy" cycles is what was already present in testpmd under the core_cycles report existing feature: get_end_cycles was only called with nb_rx + nb_tx > 0. The only change with this patch is its internal name, there is no addition on this topic. But this patch adds "total_cycles" for testpmd... > > > However, I agree that this should be updated to take all cycles into > account (as much as it is possible with the current code base). Maybe > this could be done as a separate patch or do you want to include it in > this series? ... and its implementation seems non compliant with the lcore_usage API as discussed in patch 2. As for how much cycles are counted as busy (meaning, should we count cycles spent in the mainloop too), I think it is better but that would be a change in the core_cycles report existing feature. I'd really like to hear from testpmd maintainers. -- David Marchand