git: 6f19077eaf50 - stable/13 - powernv: Include NUMA locality information in the CPU topology

[Mark Johnston]

The branch stable/13 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=6f19077eaf5087ca1a8f755a30ccf30804bf59b7

commit 6f19077eaf5087ca1a8f755a30ccf30804bf59b7
Author:     Mark Johnston <markj at FreeBSD.org>
AuthorDate: 2021-04-01 14:25:57 +0000
Commit:     Mark Johnston <markj at FreeBSD.org>
CommitDate: 2021-04-15 13:44:03 +0000

    powernv: Include NUMA locality information in the CPU topology
    
    ULE uses this topology to try and preserve locality when migrating
    threads between CPUs and when performing work stealing.  Ensure that on
    NUMA systems it will at least take the NUMA topology into account.
    
    Reviewed by:    bdragon, jhibbits (previous version)
    Tested by:      bdragon
    Differential Revision:  https://reviews.freebsd.org/D28580
    
    (cherry picked from commit cb5f8694a522ab9a80f9f0bd321d8f3ed818dd9b)
---
 sys/powerpc/powernv/platform_powernv.c | 66 +++++++++++++++++++++++++++++-----
 1 file changed, 58 insertions(+), 8 deletions(-)

diff --git a/sys/powerpc/powernv/platform_powernv.c b/sys/powerpc/powernv/platform_powernv.c
index d7acc544c2ed..8c7da5c257ee 100644
--- a/sys/powerpc/powernv/platform_powernv.c
+++ b/sys/powerpc/powernv/platform_powernv.c
@@ -480,22 +480,72 @@ powernv_smp_probe_threads(platform_t plat)
 		mp_ncores = mp_ncpus / nthreads;
 }
 
+static struct cpu_group *
+cpu_group_init(struct cpu_group *group, struct cpu_group *parent,
+    const cpuset_t *cpus, int children, int level, int flags)
+{
+	struct cpu_group *child;
+
+	child = children != 0 ? smp_topo_alloc(children) : NULL;
+
+	group->cg_parent = parent;
+	group->cg_child = child;
+	CPU_COPY(cpus, &group->cg_mask);
+	group->cg_count = CPU_COUNT(cpus);
+	group->cg_children = children;
+	group->cg_level = level;
+	group->cg_flags = flags;
+
+	return (child);
+}
+
 static struct cpu_group *
 powernv_smp_topo(platform_t plat)
 {
+	struct cpu_group *core, *dom, *root;
+	cpuset_t corecpus, domcpus;
+	int cpuid, i, j, k, ncores;
+
 	if (mp_ncpus % smp_threads_per_core != 0) {
-		printf("WARNING: Irregular SMP topology. Performance may be "
-		     "suboptimal (%d threads, %d on first core)\n",
-		     mp_ncpus, smp_threads_per_core);
+		printf("%s: irregular SMP topology (%d threads, %d per core)\n",
+		    __func__, mp_ncpus, smp_threads_per_core);
 		return (smp_topo_none());
 	}
 
-	/* Don't do anything fancier for non-threaded SMP */
-	if (smp_threads_per_core == 1)
-		return (smp_topo_none());
+	root = smp_topo_alloc(1);
+	dom = cpu_group_init(root, NULL, &all_cpus, vm_ndomains, CG_SHARE_NONE,
+	    0);
+
+	/*
+	 * Redundant layers will be collapsed by the caller so we don't need a
+	 * special case for a single domain.
+	 */
+	for (i = 0; i < vm_ndomains; i++, dom++) {
+		CPU_COPY(&cpuset_domain[i], &domcpus);
+		ncores = CPU_COUNT(&domcpus) / smp_threads_per_core;
+		KASSERT(CPU_COUNT(&domcpus) % smp_threads_per_core == 0,
+		    ("%s: domain %d core count not divisible by thread count",
+		    __func__, i));
+
+		core = cpu_group_init(dom, root, &domcpus, ncores, CG_SHARE_L3,
+		    0);
+		for (j = 0; j < ncores; j++, core++) {
+			/*
+			 * Assume that consecutive CPU IDs correspond to sibling
+			 * threads.
+			 */
+			CPU_ZERO(&corecpus);
+			for (k = 0; k < smp_threads_per_core; k++) {
+				cpuid = CPU_FFS(&domcpus) - 1;
+				CPU_CLR(cpuid, &domcpus);
+				CPU_SET(cpuid, &corecpus);
+			}
+			(void)cpu_group_init(core, dom, &corecpus, 0,
+			    CG_SHARE_L1, CG_FLAG_SMT);
+		}
+	}
 
-	return (smp_topo_1level(CG_SHARE_L1, smp_threads_per_core,
-	    CG_FLAG_SMT));
+	return (root);
 }
 
 #endif