From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 325BBC3ABA3 for ; Fri, 2 May 2025 11:35:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=PSEnJt7GA6N2U1lUXu5ucgjhIZf1JuRHb5Bjflr/dfg=; b=n1iYIMFEuFCkvT vLqIl8RmBCm1ybUb8d+2lXR/Jd7kKvkbRIswzU9Y1MBKzOBQTPH3j47R6+LB7o+3Dw5vtwGHUolq1 s1txmzyq4QEBvLKoNrB/mHstMkJ5cbTZS9xlxj5cv8J5lB1mw7HQmmcVk2CXKjdwzZlKvkXOnTf5H 2sUk3Th8XEojuxByPc5AuybbROihomXqPcL1P7GFGVzmRlVQwVbkh4F0E2FTGlhoc/OSHIeF1Cz41 +7QOprnThW99Br53q+J9S2cAuviu0BRCuqYspKIe7PWw423QKsO2R12j+LhjeMy/fe+Vgdc6Imi5D 8Vrp5XMwbcjsOOn5QNTg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uAog9-00000001nK2-2oLc; Fri, 02 May 2025 11:35:41 +0000 Received: from casper.infradead.org ([90.155.50.34]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uAoZ4-00000001mT4-0vcB; Fri, 02 May 2025 11:28:22 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=PRPW/uDt3qcKT5KOPbhmERJnNbucXaeqN2L1IjyyPX4=; b=lmV94JNEzV4MsUJuxpPUrg3Bax VPmVO1/zySgMAd5F2IJnFvPiwZNPECAQ1noECVKMioFjFmA+n5SOAzV+kGbk/f9S1iWtVP9rLg6cZ hHF7SAR0m7IaJh5tCHy2qA/R/vkevPz7ZR3+xa+Zh5GSLdg0ezbI6iHsuifF9HE00+OjyODMdnQyb JkPl44vhH6EmamOKaWacZeeUgT5U6RxA5F79Ex/83F13pJOquOWPbK7ely8gHy1uVeRQNWbA0aBQP f+nYHty39Jk6K+NlHv/lPYoCn7B5BgUPqoEMb82IHPQShd8FJim54uJ17ucrfOJGKm432KMXzRw1R RwhYSB9w==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uAoTJ-0000000FKnO-0XWf; Fri, 02 May 2025 11:22:27 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 6C1A530057C; Fri, 2 May 2025 13:22:16 +0200 (CEST) Date: Fri, 2 May 2025 13:22:16 +0200 From: Peter Zijlstra To: Dave Hansen Cc: Steven Rostedt , Valentin Schneider , linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, linux-perf-users@vger.kernel.org, kvm@vger.kernel.org, linux-arch@vger.kernel.org, linux-modules@vger.kernel.org, linux-trace-kernel@vger.kernel.org, rcu@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kselftest@vger.kernel.org, bpf@vger.kernel.org, Juri Lelli , Marcelo Tosatti , Yair Podemsky , Josh Poimboeuf , Daniel Wagner , Petr Tesarik , Nicolas Saenz Julienne , Frederic Weisbecker , "Paul E. McKenney" , Dave Hansen , Sean Christopherson , Juergen Gross , Ajay Kaher , Alexey Makhalov , Broadcom internal kernel review list , Russell King , Catalin Marinas , Will Deacon , Huacai Chen , WANG Xuerui , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , Pawan Gupta , Paolo Bonzini , Arnd Bergmann , Jason Baron , Ard Biesheuvel , Luis Chamberlain , Petr Pavlu , Sami Tolvanen , Daniel Gomez , Naveen N Rao , Anil S Keshavamurthy , "David S. Miller" , Masami Hiramatsu , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Kees Cook , Shuah Khan , Masahiro Yamada , Alice Ryhl , Miguel Ojeda , "Mike Rapoport (Microsoft)" , Rong Xu , Rafael Aquini , Song Liu , Andrii Nakryiko , Dan Carpenter , Brian Gerst , "Kirill A. Shutemov" , Benjamin Berg , Vishal Annapurve , Randy Dunlap , John Stultz , Tiezhu Yang Subject: Re: [PATCH v5 00/25] context_tracking,x86: Defer some IPIs until a user->kernel transition Message-ID: <20250502112216.GZ4198@noisy.programming.kicks-ass.net> References: <20250429113242.998312-1-vschneid@redhat.com> <20250430132047.01d48647@gandalf.local.home> <019f6713-cfbd-466b-8fb5-dcd982cf8644@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <019f6713-cfbd-466b-8fb5-dcd982cf8644@intel.com> X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Wed, Apr 30, 2025 at 11:07:35AM -0700, Dave Hansen wrote: > Both AMD and Intel have hardware to do it. ARM CPUs do it too, I think. > You can go buy the Intel hardware off the shelf today. To be fair, the Intel RAR thing is pretty horrific :-( Definitely sub-par compared to the AMD and ARM things. Furthermore, the paper states it is a uarch feature for SPR with no guarantee future uarchs will get it (and to be fair, I'd prefer it if they didn't). Furthermore, I suspect it will actually be slower than IPIs for anything with more than 64 logical CPUs due to reduced parallelism. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv