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Fri, 04 Nov 2022 09:02:01 +0000 Date: Fri, 04 Nov 2022 09:02:00 +0000 Message-ID: <86edujqeif.wl-maz@kernel.org> From: Marc Zyngier To: Usama Arif Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-doc@vger.kernel.org, virtualization@lists.linux-foundation.org, linux@armlinux.org.uk, yezengruan@huawei.com, catalin.marinas@arm.com, will@kernel.org, steven.price@arm.com, mark.rutland@arm.com, bagasdotme@gmail.com, fam.zheng@bytedance.com, liangma@liangbit.com, punit.agrawal@bytedance.com Subject: Re: [v2 0/6] KVM: arm64: implement vcpu_is_preempted check In-Reply-To: <20221104062105.4119003-1-usama.arif@bytedance.com> References: <20221104062105.4119003-1-usama.arif@bytedance.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: usama.arif@bytedance.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-doc@vger.kernel.org, virtualization@lists.linux-foundation.org, linux@armlinux.org.uk, yezengruan@huawei.com, catalin.marinas@arm.com, will@kernel.org, steven.price@arm.com, mark.rutland@arm.com, bagasdotme@gmail.com, fam.zheng@bytedance.com, liangma@liangbit.com, punit.agrawal@bytedance.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-Spam-Status: No, score=-8.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 04 Nov 2022 06:20:59 +0000, Usama Arif wrote: > > This patchset adds support for vcpu_is_preempted in arm64, which allows the guest > to check if a vcpu was scheduled out, which is useful to know incase it was > holding a lock. vcpu_is_preempted can be used to improve > performance in locking (see owner_on_cpu usage in mutex_spin_on_owner, > mutex_can_spin_on_owner, rtmutex_spin_on_owner and osq_lock) and scheduling > (see available_idle_cpu which is used in several places in kernel/sched/fair.c > for e.g. in wake_affine to determine which CPU can run soonest): Please refrain from reposting a series only two days after the initial one. One week is a minimum, and only if there is enough review comments to justify a respin (there were no valuable comments so far). Reposting more often only results in the review process being exponentially delayed. Thanks, M. -- Without deviation from the norm, progress is not possible.