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Wed, 28 Feb 2024 00:32:47 -0800 (PST) Received: from archie.me ([103.124.138.155]) by smtp.gmail.com with ESMTPSA id sy12-20020a17090b2d0c00b00296f4fc7e60sm962560pjb.12.2024.02.28.00.32.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Feb 2024 00:32:47 -0800 (PST) Received: by archie.me (Postfix, from userid 1000) id D8B75187DBEB7; Wed, 28 Feb 2024 15:32:41 +0700 (WIB) Date: Wed, 28 Feb 2024 15:32:41 +0700 From: Bagas Sanjaya To: Abdul Anshad Azeez , edumazet@google.com, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, corbet@lwn.net, dsahern@kernel.org, Linux Networking , Linux Kernel Mailing List , Linux Regressions Cc: Boon Ang , John Savanyo , Peter Jonasson , Rajender M Subject: Re: Network performance regression in Linux kernel 6.6 for small socket size test cases Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="aJ0FkAcvBcopWHIX" Content-Disposition: inline In-Reply-To: --aJ0FkAcvBcopWHIX Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable [also Cc: regressions ML] On Wed, Feb 28, 2024 at 12:13:27PM +0530, Abdul Anshad Azeez wrote: > During performance regression workload execution of the Linux > kernel we observed up to 30% performance decrease in a specific networking > workload on the 6.6 kernel compared to 6.5 (details below). The regressio= n is > reproducible in both Linux VMs running on ESXi and bare metal Linux. >=20 > Workload details: >=20 > Benchmark - Netperf TCP_STREAM > Socket buffer size - 8K > Message size - 256B > MTU - 1500B > Socket option - TCP_NODELAY > # of STREAMs - 32 > Direction - Uni-Directional Receive > Duration - 60 Seconds > NIC - Mellanox Technologies ConnectX-6 Dx EN 100G > Server Config - Intel(R) Xeon(R) Gold 6348 CPU @ 2.60GHz & 512G Memory >=20 > Bisect between 6.5 and 6.6 kernel concluded that this regression originat= ed > from the below commit: >=20 > commit - dfa2f0483360d4d6f2324405464c9f281156bd87 (tcp: get rid of > sysctl_tcp_adv_win_scale) > Author - Eric Dumazet > Link - > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit= /?id=3D > dfa2f0483360d4d6f2324405464c9f281156bd87 >=20 > Performance data for (Linux VM on ESXi): > Test case - TCP_STREAM_RECV Throughput in Gbps > (for different socket buffer sizes and with constant message size - 256B): >=20 > Socket buffer size - [LK6.5 vs LK6.6] > 8K - [8.4 vs 5.9 Gbps] > 16K - [13.4 vs 10.6 Gbps] > 32K - [19.1 vs 16.3 Gbps] > 64K - [19.6 vs 19.7 Gbps] > Autotune - [19.7 vs 19.6 Gbps] >=20 > >From the above performance data, we can infer that: > * Regression is specific to lower fixed socket buffer sizes (8K, 16K & 32= K). > * Increasing the socket buffer size gradually decreases the throughput im= pact. > * Performance is equal for higher fixed socket size (64K) and Autotune so= cket > tests. >=20 > We would like to know if there are any opportunities for optimization in > the test cases with small socket sizes. >=20 Can you verify the regression on current mainline (v6.8-rc6)? --=20 An old man doll... just what I always wanted! - Clara --aJ0FkAcvBcopWHIX Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQSSYQ6Cy7oyFNCHrUH2uYlJVVFOowUCZd7vpAAKCRD2uYlJVVFO o3FWAQDe+PbGL4LW/N1x23XLUSDEsqAGX9WqhwvPNQEir1nE3gEAqt155Cln5op5 oMAlTfo6KFQ5Sl5qdUv70rbcuu4T+gs= =88Qq -----END PGP SIGNATURE----- --aJ0FkAcvBcopWHIX--