From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj2-f12.google.com (mail-pj2-f12.google.com [74.125.227.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20C77429CEC for ; Tue, 22 Sep 2026 08:45:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.227.140 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790066719; cv=none; b=a27Fy1BXeWFbAT/DQPnobjocgkbXRFonmUIEVv1QPaEEDpBSDgiChWrDKe8jro9umdfHpUAkvXee7E52hD6K6caX0vFaKmNR3MMq/qKKmml4HPu80yEhtfxvFD+RtIHPEbFMAd/eqfGB8hMTgYWo4dS1X3J0UgH6vE0qXjGc1Io= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790066719; c=relaxed/simple; bh=rWOXTAtkNKBbD+uEgNV1nTyqhko/HqdFlDPSq6vVwJM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BzHs0Oj0FJQcByVGOHrKRFqtI3BfopdAt1bEJzBLfyZvE5tXet7FoHxXrNqCX5huOCY/KpDPh3qMVmRHW37xRarhaZLvKql0442/yyfrQwZPYx37ww2QnwDpW7zwaploxPFNKRAKwbCij4rR6jt6hBXREG3mdxpT8297pJEJQZU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=JDiHSjJw; arc=none smtp.client-ip=74.125.227.140 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JDiHSjJw" Received: by mail-pj2-f12.google.com with SMTP id d9443c01a7336-2d747eefae4so12031035ad.0 for ; Tue, 22 Sep 2026 01:45:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790066717; x=1790671517; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=rWOXTAtkNKBbD+uEgNV1nTyqhko/HqdFlDPSq6vVwJM=; b=JDiHSjJwHZTGuhFG4Yb7PLcjNAdg2cPNH07nQl7euJYOZgF37nMxsEDqb4Pk+uFQMw fYZ6LwDyaJqqiVvkB6+WGwLq+bF6PYBNPQXuMfFZ16FcoA0HUmvBEDlWdE1jr//aK6b3 g7xiScS9qW5E06jUIiwo8yvb7ITLPRobdIyyyCN4x9Jp4G0lKz3vbAaNSyjHC7KneFkd YgGwTz61AaWyGB+3fhvmdRVlcu9TWub1iZHiy+mmLovF0CVgTPRNJh3mhzBQrXQYAVDF aWDIK1yV2GOnovj1HQsC6SMATNU2e9BFj4tTRJeUMKXF1I/DdOgByd0ayAEblP51k1B7 Z59Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790066717; x=1790671517; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=rWOXTAtkNKBbD+uEgNV1nTyqhko/HqdFlDPSq6vVwJM=; b=wuEeXlTMrQG84u/gcnthCjX22eVBzDqikVkYFbKWRNIO17GELhO0sAdIb51cstX4Qd 2UnTObqMjjMS/nTFMUGVMnIBvd8eKBi8itysDGmWEf6PQog8ctK4IDe+8cdPrtm/sRzM G8tH6yOeESpMi5PugKRpqGBQhuLaVwqAxN8AQH5trE+UCmL9E7mZZ977gtWHpfZBJpok zbxYNCsh1Ro6fUOiKTVR796hSrqBhKA+ppzpbyBZSys5UrF/JVFF+1Ftzhy6SOG9eT1E henunT7iUSqrzhr6AEET/7oGtO2B+Mnst50osMXjaBroHlcWfXxwKaFEOQDujjAJKor+ jqDQ== X-Forwarded-Encrypted: i=1; AKwUvBy4NkyV4sw/p2iHt+Ba8OzASYl35/B8R4rXhP26CGp2XHeGVmsxKFlC+hhrXoo7qoCbhZU=@vger.kernel.org X-Gm-Message-State: AFuF++nQE5HYV5Y25tw4b1gRnbpUlKQ8bP0pGL5DQzuAyp8zZ0N7OTLX PwxLux19fCk3LcYEjf5yMEd+fW2dnaXmKECmVhfi0g53acKUmdxUM0hg X-Gm-Gg: AYBFou3yPkmOYF+dgoHEEYP7pmFiv6q7jT3dKlXogTTNrTdeGNTYIm637RjQCeEy38v ObyiN2WzDZJDpdAt6LCnrQfTCxsMg7Obdf2eEX1iizxnje7yfQI5e0ET05XI7iLVTw0p7skiXPo 2646Qdn3G0Uv5bm8OoabdjGTfdz8O1giwyYpz9hllnztpBTs1oVSkdFNooi0zaqH1g0RYSJz/ik 8Hyj1Obl6G3zfPji4QkNX+Q2RKeCEVAR/o5uZnnuSj1koLWtANzywCMYUwMCJDhS+EQJOeHV1g0 BEN0fgu/TkhTbL0WMYP/IEk1lffS0ATjghSP8gNAJ0NCh+IZoFVaeaWpeFXYkE2HzB5QJcGA22J W5vL3KLyrU5OJj+zjBfNu84+goCbgyGlbNzb4cPBd/Mqr72fOxmpHpSA1nhJPHM8CA22KF/QnPT +H6UufhIfGye3LswqLpVMoqROYzDPpYJBc5KIi2d4E0XHszzzVO7kQRNR6/ykgry5eq4TYvpI3f t6FxM9EKNC2CHLpJcowBSCzv8IVWlamBYkrTBwn X-Received: by 2002:a17:902:e952:b0:2dd:c100:251d with SMTP id d9443c01a7336-2df60f2fd27mr3267025ad.38.1790066717422; Tue, 22 Sep 2026 01:45:17 -0700 (PDT) Received: from localhost.localdomain (vmi2317699.contaboserver.net. [85.239.239.237]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2df5d0588e9sm6100495ad.76.2026.09.22.01.44.59 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 22 Sep 2026 01:45:16 -0700 (PDT) From: Lian Wang To: Boqun Feng Cc: Kunwu Chan , stern@rowland.harvard.edu, parri.andrea@gmail.com, will@kernel.org, peterz@infradead.org, npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr, paulmck@kernel.org, corbet@lwn.net, mingo@redhat.com, dave@stgolabs.net, josh@joshtriplett.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, urezki@gmail.com, akiyks@gmail.com, dlustig@nvidia.com, joelagnelf@nvidia.com, skhan@linuxfoundation.org, rdunlap@infradead.org, longman@redhat.com, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, include@grrlz.net, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, lkmm@lists.linux.dev, linux-doc@vger.kernel.org, rcu@vger.kernel.org, lianux.mm@gmail.com Subject: Re: [RFC/WIP PATCH 1/4] hazptr: add shared-scan kthread Date: Tue, 22 Sep 2026 16:44:37 +0800 Message-ID: <20260922084447.58084-1-lianux.mm@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: References: <20260922070950.4173245-1-kunwu.chan@gmail.com> <20260922070950.4173245-2-kunwu.chan@gmail.com> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Boqun, Thanks for the suggestion. Kunwu and I will work together on the next iteration of the shared-scan design, including your idea of avoiding per-synchronize allocations with a Bloom filter. We will also run the rcuscale comparisons and collect IPI counts for the lockdep workloads you suggested, then share the results with the thread. Thanks, Lian On Tue, 22 Sep 2026 10:28:24 +0200 Boqun Feng wrote: > This would requires allocation during hazptr_synchronize() and I would > like to avoid that (it's going to introduce a "allocating memory to free > memory" case). > > Mathieu brought up a useful data structure for the scan: A Bloom filter: > > Willing to give it a try?