From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZo3JBPyMDq10S54kW8lrAyHw6l2BosvGCV0SDroJoFf1dwvASm71RSIM1AnXYoevdNtaZfx ARC-Seal: i=1; a=rsa-sha256; t=1525261764; cv=none; d=google.com; s=arc-20160816; b=pe31adQXvdNWZR/ymzxplMMojPU3ctrNhjgSkDuE2n3po0LPhCWHXGvOoGKtF8Ik3z h1bFsHBb+ojTsT0vXAWiBHzI10oCvvdWJgYUIZ3jGnSBgCxQo8Uw51ZsgPwbs7kconuz hRm6zD8Hpimi9f6UN++3KzVnwnpmS7hgaxjPBTQF5LZy4MaavXJ2tgGL27AVwGN5jS+0 OqAzM6OD+iawODocW24aAeIj4/QYyqJb346PvMu/zd7MCI7Fj722ueO6Hxcz6O5FjGEt H6UACw1tRLu6MLbgF4cTVuRNoq4Nbwh5OVKCC6m+nHzVH13W40lbG1JDkY40rheg7DJT dCLg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:arc-authentication-results; bh=t8j6xggV8t+v+xvb6TAjuWAzZ7BmrX1W+W/WtmeJVAc=; b=tielReIkb39EBaT7++kj8mLOjK+bqgUA9vaFnHlG0qhunFvBAMw/Jz6Pl2fJ7vmWmc I4huTb6ywX4p14QtICmxVDfMOaClNjc3sMmQBmxSULetxakvmpvDHLYLLomZpYeBjFI2 TTN29h9ll4o9YD1MdokfyQOjbeWNQrB0TjS3mIaTTZCdHsK1potlARI8Li7MVlDFFKLh I8Ek58ld+UqlbZ4ig0Vf5Xwkq55vMjkEf/jsFcg2yA6fLFQVKcMEdIwLz6FCB6pdsNMh nslmJgvpo5EYI6sWWcfMAog/adS8oRIhi57LhuQDby7j7qdbckN0ZdSckclE+J+NzFdm 71Lg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of morten.rasmussen@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=morten.rasmussen@arm.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of morten.rasmussen@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=morten.rasmussen@arm.com Date: Wed, 2 May 2018 12:49:16 +0100 From: Morten Rasmussen To: Sudeep Holla Cc: Jeremy Linton , linux-acpi@vger.kernel.org, Mark.Rutland@arm.com, austinwc@codeaurora.org, tnowicki@caviumnetworks.com, Catalin.Marinas@arm.com, palmer@sifive.com, Will.Deacon@arm.com, linux-riscv@lists.infradead.org, vkilari@codeaurora.org, Lorenzo.Pieralisi@arm.com, ahs3@redhat.com, lenb@kernel.org, john.garry@huawei.com, wangxiongfeng2@huawei.com, jhugo@qti.qualcomm.com, Dietmar.Eggemann@arm.com, linux-arm-kernel@lists.infradead.org, ard.biesheuvel@linaro.org, gregkh@linuxfoundation.org, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, timur@qti.qualcomm.com, hanjun.guo@linaro.org Subject: Re: [PATCH v8 13/13] arm64: topology: divorce MC scheduling domain from core_siblings Message-ID: <20180502114916.GW4589@e105550-lin.cambridge.arm.com> References: <20180425233121.13270-1-jeremy.linton@arm.com> <20180425233121.13270-14-jeremy.linton@arm.com> <62677b95-faf5-4908-abc9-428ef39ea912@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <62677b95-faf5-4908-abc9-428ef39ea912@arm.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1598766330955487456?= X-GMAIL-MSGID: =?utf-8?q?1599352879702434347?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tue, May 01, 2018 at 03:33:33PM +0100, Sudeep Holla wrote: > > > On 26/04/18 00:31, 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 > > --- > > arch/arm64/include/asm/topology.h | 2 ++ > > arch/arm64/kernel/topology.c | 32 +++++++++++++++++++++++++++++++- > > 2 files changed, 33 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h > > index 6b10459e6905..df48212f767b 100644 > > --- a/arch/arm64/include/asm/topology.h > > +++ b/arch/arm64/include/asm/topology.h > > @@ -8,8 +8,10 @@ struct cpu_topology { > > int thread_id; > > int core_id; > > int package_id; > > + int llc_id; > > cpumask_t thread_sibling; > > cpumask_t core_sibling; > > + cpumask_t llc_siblings; > > }; > > > > extern struct cpu_topology cpu_topology[NR_CPUS]; > > diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c > > index bd1aae438a31..20b4341dc527 100644 > > --- a/arch/arm64/kernel/topology.c > > +++ b/arch/arm64/kernel/topology.c > > @@ -13,6 +13,7 @@ > > > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -214,7 +215,19 @@ EXPORT_SYMBOL_GPL(cpu_topology); > > > > const struct cpumask *cpu_coregroup_mask(int cpu) > > { > > - return &cpu_topology[cpu].core_sibling; > > + const cpumask_t *core_mask = cpumask_of_node(cpu_to_node(cpu)); > > + > > + /* Find the smaller of NUMA, core or LLC siblings */ > > + if (cpumask_subset(&cpu_topology[cpu].core_sibling, core_mask)) { > > + /* not numa in package, lets use the package siblings */ > > + core_mask = &cpu_topology[cpu].core_sibling; > > + } > > + if (cpu_topology[cpu].llc_id != -1) { > > + if (cpumask_subset(&cpu_topology[cpu].llc_siblings, core_mask)) > > + core_mask = &cpu_topology[cpu].llc_siblings; > > + } > > + > > + return core_mask; > > } > > > > static void update_siblings_masks(unsigned int cpuid) > > @@ -226,6 +239,9 @@ static void update_siblings_masks(unsigned int cpuid) > > for_each_possible_cpu(cpu) { > > cpu_topo = &cpu_topology[cpu]; > > > > + if (cpuid_topo->llc_id == cpu_topo->llc_id) > > + cpumask_set_cpu(cpu, &cpuid_topo->llc_siblings); > > + > > Would this not result in cpuid_topo->llc_siblings = cpu_possible_mask > on DT systems where llc_id is not set/defaults to -1 and still pass the > condition. Does it make sense to add additional -1 check ? I don't think mask will be used by the current code if llc_id == -1 as the user does the check. Is it better to have the mask empty than default to cpu_possible_mask? If we require all users to implement a check it shouldn't matter.