From mboxrd@z Thu Jan 1 00:00:00 1970 From: Morten Rasmussen Subject: Re: [PATCH v8 13/13] arm64: topology: divorce MC scheduling domain from core_siblings Date: Thu, 3 May 2018 16:12:55 +0100 Message-ID: <20180503151255.GB28409@work-enc> References: <20180425233121.13270-1-jeremy.linton@arm.com> <20180425233121.13270-14-jeremy.linton@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20180425233121.13270-14-jeremy.linton@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Jeremy Linton Cc: linux-acpi@vger.kernel.org, Sudeep.Holla@arm.com, linux-arm-kernel@lists.infradead.org, Lorenzo.Pieralisi@arm.com, hanjun.guo@linaro.org, rjw@rjwysocki.net, Will.Deacon@arm.com, Catalin.Marinas@arm.com, gregkh@linuxfoundation.org, Mark.Rutland@arm.com, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, wangxiongfeng2@huawei.com, vkilari@codeaurora.org, ahs3@redhat.com, Dietmar.Eggemann@arm.com, palmer@sifive.com, lenb@kernel.org, john.garry@huawei.com, austinwc@codeaurora.org, tnowicki@caviumnetworks.com, jhugo@qti.qualcomm.com, timur@qti.qualcomm.com, ard.biesheuvel@linaro.org List-Id: linux-acpi@vger.kernel.org On Wed, Apr 25, 2018 at 06:31:21PM -0500, Jeremy Linton wrote: > Now that we have an accurate view of the physical topology > we need to represent it correctly to the scheduler. Generally MC > should equal the LLC in the system, but there are a number of > special cases that need to be dealt with. > > In the case of NUMA in socket, we need to assure that the sched > domain we build for the MC layer isn't larger than the DIE above it. > Similarly for LLC's that might exist in cross socket interconnect or > directory hardware we need to assure that MC is shrunk to the socket > or NUMA node. > > This patch builds a sibling mask for the LLC, and then picks the > smallest of LLC, socket siblings, or NUMA node siblings, which > gives us the behavior described above. This is ever so slightly > different than the similar alternative where we look for a cache > layer less than or equal to the socket/NUMA siblings. > > The logic to pick the MC layer affects all arm64 machines, but > only changes the behavior for DT/MPIDR systems if the NUMA domain > is smaller than the core siblings (generally set to the cluster). > Potentially this fixes a possible bug in DT systems, but really > it only affects ACPI systems where the core siblings is correctly > set to the socket siblings. Thus all currently available ACPI > systems should have MC equal to LLC, including the NUMA in socket > machines where the LLC is partitioned between the NUMA nodes. > > Signed-off-by: Jeremy Linton This patch looks good to me. Acked-by: Morten Rasmussen