From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 0098A48A90; Mon, 3 Nov 2025 19:48:12 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id E839340647; Mon, 3 Nov 2025 19:48:12 +0100 (CET) Received: from mail-pl1-f170.google.com (mail-pl1-f170.google.com [209.85.214.170]) by mails.dpdk.org (Postfix) with ESMTP id 1207C40431 for ; Mon, 3 Nov 2025 19:48:11 +0100 (CET) Received: by mail-pl1-f170.google.com with SMTP id d9443c01a7336-294fd2ca6acso36034195ad.0 for ; Mon, 03 Nov 2025 10:48:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20230601.gappssmtp.com; s=20230601; t=1762195691; x=1762800491; darn=dpdk.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=qWGJGMvKKg++E5vR2AfvdS8BaCq/dBU10wksR0lzh1Y=; b=rUIVU8NZoaQlzgfgzGHqLO/IDb+1CrJ0MbdiLwcUpUL/5eb0xIYucr7fmIOW8EwPRW 0qDsM2BcsnYQGC6FTtuo0QtkVboR9wJXal4HmsvzALUjhPPmEpqYYMrS9P0VX2uT4gnq 8R3FHk2idaJYu1whl8ia3b6oyT/8H7ODtqhdEqWPAOlwCKv3LdCfpPwtA3c1gBTYpn5j Saa1Akwuc841aZkX/JGeFODUwR5F6gy5wksHOOB+biefwnAvyh6pfCaPMjSSTxYgx3Y0 g7i1R/XmsXD0Y+1yI+c1mSm9Zh6TytoHVcQnoI74vcCC9deKJ5sClefeC8rDkKDnqOQb nF1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762195691; x=1762800491; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=qWGJGMvKKg++E5vR2AfvdS8BaCq/dBU10wksR0lzh1Y=; b=Z16ubtHOoRqq2HCHpqkfWZyB9m1mWFhM6le4zW6kh0/jeFxMoyRILS+tlxktNZn1qq u9NLy169Z57IEds3Cgu09RESQQwXH+/kyxRZHpB3RnHoZkNpH9flagnNAve0a3aawsbF 9tU3Vge1uP4MMhCsKvZ1Qr0Eg8vGYNnmhEiZ3Flb0XSuByv/DihGeOjP26MauZdfPtc5 RAbAnLNsEusQsp4V1nJEiIHZbWeG2HtlpD/sIqpeHeMOZ4SfK/tKG/dhbeguRHrgKUAi /h+38CL5UaaDAWzmopCVdO1XW484zSkuSxBmUs5v+7iQPpXrGec4QPa8EdohkrjR8uKz PmTA== X-Forwarded-Encrypted: i=1; AJvYcCXeKoGJsqY0WLp9oYg/ubnlHO5ndlvHaWAPRZ6lhlZ/obg2q1odNP5pS8+U6HG9llhHOWk=@dpdk.org X-Gm-Message-State: AOJu0YyIRhY8BIJFuuCRL4wF5jn6xNT1j/Dev0XJ8kKQVSFNH1LdHZWe z+3mCQluo/qVtkr+XktQ8c54KsM93TJ4vHGGeTuJmIdxmXa38eV03xDMq589TG1MwzU= X-Gm-Gg: ASbGnct2Pfjo/BY4XpOY+OAL/LVALBFismd7zhla+vwUyQ3AMrl4ZXRF0pGZ2C2sBcL 42rjAoDjmv1PUoW78v4fr5MIzdcK4Db9YHrzNQZOjepPUmEVHFRDXklnMH1Hou7UwtpM5FdkAiy z3/vsck6/gIf56Bt752RsfU9s0PGoyQwIBqMsYrMd87hlFjQB/0r2ofmjJjL6PDRRPDe9G4/PII DOxhRw8sKa4sCtngLZkbUjqvlPvfk6Q7mcliCElb6hlP9Y+SHcSW+v9r4AH4htYSfnvI9nVwQgf yWlK2eSEDdKYJ7UmFMDeBoMDZDT9L617+xy9a7vfvwsb5ct4/RbVwrRaCrj3M8EOrhr7CFsozS3 foG4ixwhyNlQWW4xyLQy3zM7ZEAmqaNTaKWYcF3Le0iro2pE+qgtn5bhIilkbR0npVdWsppT1EB +ScLy5AV7gWcBk3vHCPoQXikJioBjdqqmXcw== X-Google-Smtp-Source: AGHT+IEgcbqfdlnRmiYzkoUzGtITKYCZxUlIQARbt3Hw6emxVYCCaiNsAThMfKAuvVu0PphG2K4lxQ== X-Received: by 2002:a17:902:d2c2:b0:295:5898:ff5c with SMTP id d9443c01a7336-295f94750d4mr5465195ad.16.1762195690977; Mon, 03 Nov 2025 10:48:10 -0800 (PST) Received: from phoenix (204-195-96-226.wavecable.com. [204.195.96.226]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2952774570bsm126083295ad.99.2025.11.03.10.48.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Nov 2025 10:48:10 -0800 (PST) Date: Mon, 3 Nov 2025 10:48:03 -0800 From: Stephen Hemminger To: Konstantin Ananyev Cc: Wathsala Vithanage , Honnappa Nagarahalli , Tyler Retzlaff , "dev@dpdk.org" , Ola Liljedahl , "vattunuru@marvell.com" Subject: Re: [PATCH 1/1] eal: correct memory ordering in MCS lock Message-ID: <20251103104803.30464227@phoenix> In-Reply-To: References: <20251023184724.1759497-1-wathsala.vithanage@arm.com> <20251103090717.2d181d95@phoenix> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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 Mon, 3 Nov 2025 18:06:05 +0000 Konstantin Ananyev wrote: > > > > On 11/3/25 11:07, Stephen Hemminger wrote: > > > On Mon, 3 Nov 2025 09:12:39 -0600 > > > Wathsala Vithanage wrote: > > > > > >> MCS lock is broken, it's just a matter of time it will run into a deadlock. > > >> > > >> drivers/dma/cnxk is a user of MCS lock. > > > I am surprised that a driver would use mcslock. > > > MCSlock is targeted at case of large number of CPU's with lots of contention. > > > It will likely be slower than spinlock or ticketlock for the use case of driver. > > It appears in |drivers/dma/cnxk/cnxk_dmadev_fp.c|, perhaps the > > maintainer can clarify. > > > > If MCS lock is really broken, it needs to be fixed anyway. > It might be used by other third-party libs/apps that do use on DPDK. 100% agree it must be fixed. It would be good to have test or static analysis tool that could validate all the lock types.