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[213.179.129.39]) by smtp.gmail.com with ESMTPSA id s26-20020a7bc39a000000b003f42328b5d9sm4792425wmj.39.2023.05.26.03.44.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 May 2023 03:44:05 -0700 (PDT) Date: Fri, 26 May 2023 12:44:04 +0200 From: Jiri Pirko To: Haiyang Zhang Cc: linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, decui@microsoft.com, kys@microsoft.com, paulros@microsoft.com, olaf@aepfle.de, vkuznets@redhat.com, davem@davemloft.net, wei.liu@kernel.org, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, leon@kernel.org, longli@microsoft.com, ssengar@linux.microsoft.com, linux-rdma@vger.kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, bpf@vger.kernel.org, ast@kernel.org, sharmaajay@microsoft.com, hawk@kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH net] net: mana: Fix perf regression: remove rx_cqes, tx_cqes counters Message-ID: References: <1684963320-25282-1-git-send-email-haiyangz@microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1684963320-25282-1-git-send-email-haiyangz@microsoft.com> Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org Wed, May 24, 2023 at 11:22:00PM CEST, haiyangz@microsoft.com wrote: >The apc->eth_stats.rx_cqes is one per NIC (vport), and it's on the >frequent and parallel code path of all queues. So, r/w into this >single shared variable by many threads on different CPUs creates a >lot caching and memory overhead, hence perf regression. And, it's >not accurate due to the high volume concurrent r/w. > >Since the error path of mana_poll_rx_cq() already has warnings, so >keeping the counter and convert it to a per-queue variable is not >necessary. So, just remove this counter from this high frequency >code path. > >Also, remove the tx_cqes counter for the same reason. We have >warnings & other counters for errors on that path, and don't need >to count every normal cqe processing. > >Cc: stable@vger.kernel.org >Fixes: bd7fc6e1957c ("net: mana: Add new MANA VF performance counters for easier troubleshooting") >Signed-off-by: Haiyang Zhang Reviewed-by: Jiri Pirko