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Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qBsVC-00HIVK-1L; Wed, 21 Jun 2023 07:43:43 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0B475300222; Wed, 21 Jun 2023 09:43:38 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E49482BD11718; Wed, 21 Jun 2023 09:43:37 +0200 (CEST) Date: Wed, 21 Jun 2023 09:43:37 +0200 From: Peter Zijlstra To: Yair Podemsky Cc: mtosatti@redhat.com, ppandit@redhat.com, david@redhat.com, linux@armlinux.org.uk, mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, keescook@chromium.org, paulmck@kernel.org, frederic@kernel.org, will@kernel.org, ardb@kernel.org, samitolvanen@google.com, juerg.haefliger@canonical.com, arnd@arndb.de, rmk+kernel@armlinux.org.uk, geert+renesas@glider.be, linus.walleij@linaro.org, akpm@linux-foundation.org, sebastian.reichel@collabora.com, rppt@kernel.org, aneesh.kumar@linux.ibm.com, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/2] send tlb_remove_table_smp_sync IPI only to necessary CPUs Message-ID: <20230621074337.GF2046280@hirez.programming.kicks-ass.net> References: <20230620144618.125703-1-ypodemsk@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230620144618.125703-1-ypodemsk@redhat.com> X-BeenThere: linux-arm-kernel@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-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jun 20, 2023 at 05:46:16PM +0300, Yair Podemsky wrote: > Currently the tlb_remove_table_smp_sync IPI is sent to all CPUs > indiscriminately, this causes unnecessary work and delays notable in > real-time use-cases and isolated cpus. > By limiting the IPI to only be sent to cpus referencing the effected > mm. > a config to differentiate architectures that support mm_cpumask from > those that don't will allow safe usage of this feature. > > changes from -v1: > - Previous version included a patch to only send the IPI to CPU's with > context_tracking in the kernel space, this was removed due to race > condition concerns. > - for archs that do not maintain mm_cpumask the mask used should be > cpu_online_mask (Peter Zijlstra). > Would it not be much better to fix the root cause? As per the last time, there's patches that cure the thp abuse of this. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel