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[90.233.222.113]) by smtp.gmail.com with ESMTPSA id n1-20020a2e8781000000b002a7e9e4e9dcsm1638499lji.114.2023.04.24.00.44.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Apr 2023 00:44:02 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 24 Apr 2023 09:44:00 +0200 To: Michal Hocko Cc: Uladzislau Rezki , lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org Subject: Re: [Lsf-pc] LSFMMBPF proposal [MM]: Eliminate vmap/vmalloc lock contention Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 90B1D140011 X-Stat-Signature: soipa18za8hjokib6bqp83q7c4s6mruq X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1682322244-678100 X-HE-Meta: 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 +R6PeOgs gtZRyYmeCTBUQXQbuaPEg+MkQs6If3lA8qBfNLt9dbM4PFT054tzfWJfeBLs6RKHms5zMkbltIfL9rUd/gCzIpus9fAMB1jhwfVrZvJmi2Am8fKQbQtsG7cshLX4xpcMfHf02gOpXaQA6ytw1k8Ptkh94F6GrpTWh9fu/1FQpvW5q/pcBXrbnFIPjAUXRa4n6RV3UuT9c8m7vsNHf1BE0ChkQ2dvavAo9t5O0zL6HokTHHty9YYLkad9P3DKeS7Yu8VOUeUnOzOzr7YaHnRZ6gmMqgd8xNZ2UOsW6anEREIjWOvHg+fDdyC9FxJvysXs63ZU2ElMBUmgVw9MueDnN9ynceYINgZsUI1b+AGrb7WhMeEc8IEp4Wv/H0qb+cMp6CZ8/ugx690oqFOl7gsDs9YRhFmPpwet7omZSz7eX189Hs6g= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000021, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 21, 2023 at 02:03:43PM +0200, Michal Hocko wrote: > On Tue 28-02-23 17:42:43, Uladzislau Rezki wrote: > > Hello, LSF. > > > > Title: Introduce a per-cpu-vmap-cache to eliminate a vmap lock contention > > > > Description: > > Currently the vmap code is not scaled to number of CPU cores in a system > > because a global vmap space is protected by a single spinlock. Such approach > > has a clear bottleneck if many CPUs simultaneously access to one resource. > > > > In this talk i would like to describe a drawback, show some data related > > to contentions and places where those occur in a code. Apart of that i > > would like to share ideas how to eliminate it providing a few approaches > > and compare them. > > It's been some time since you brough this up. Has there been any > progress on the topic? Do you still find it important to discuss it at > LSFMM? > The idea about sequence was/is: 1) Give an overview on the proposal; 2) Submit patches to address the problem; 3) Start a discussion over lkml with people who are interested in it; 4) Send out a complete solution. -- Uladzislau Rezki