Messages in this thread Patch in this message | | | Date | Tue, 18 Jun 2019 11:43:19 +0100 | From | Matt Fleming <> | Subject | Re: [PATCH] sched/topology: Improve load balancing on AMD EPYC |
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On Tue, 11 Jun, at 05:22:21PM, Lendacky, Thomas wrote: > On 6/10/19 4:26 PM, Matt Fleming wrote: > > On Wed, 05 Jun, at 08:00:35PM, Peter Zijlstra wrote: > >> > >> And then we had two magic values :/ > >> > >> Should we not 'fix' RECLAIM_DISTANCE for EPYC or something? Because > >> surely, if we want to load-balance agressively over 30, then so too > >> should we do node_reclaim() I'm thikning. > > > > Yeah we can fix it just for EPYC, Mel suggested that approach originally. > > > > Suravee, Tom, what's the best way to detect these EPYC machines that need to > > override RECLAIM_DISTANCE? > > You should be able to do it based on the family. There's an init_amd_zn() > function in arch/x86/kernel/cpu/amd.c. You can add something there or, > since init_amd_zn() sets X86_FEATURE_ZEN, you could check for that if you > prefer putting it in a different location.
This works for me under all my tests. Thoughts?
--->8---
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 80a405c2048a..4db4e9e7654b 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -8,6 +8,7 @@ #include <linux/sched.h> #include <linux/sched/clock.h> #include <linux/random.h> +#include <linux/topology.h> #include <asm/processor.h> #include <asm/apic.h> #include <asm/cacheinfo.h> @@ -824,6 +825,8 @@ static void init_amd_zn(struct cpuinfo_x86 *c) { set_cpu_cap(c, X86_FEATURE_ZEN); + node_reclaim_distance = 32; + /* Fix erratum 1076: CPB feature bit not being set in CPUID. */ if (!cpu_has(c, X86_FEATURE_CPB)) set_cpu_cap(c, X86_FEATURE_CPB); diff --git a/include/linux/topology.h b/include/linux/topology.h index cb0775e1ee4b..74b484354ac9 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -59,6 +59,9 @@ int arch_update_cpu_topology(void); */ #define RECLAIM_DISTANCE 30 #endif + +extern int __read_mostly node_reclaim_distance; + #ifndef PENALTY_FOR_NODE_WITH_CPUS #define PENALTY_FOR_NODE_WITH_CPUS (1) #endif diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index f53f89df837d..20f0f8f6792b 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1284,6 +1284,7 @@ static int sched_domains_curr_level; int sched_max_numa_distance; static int *sched_domains_numa_distance; static struct cpumask ***sched_domains_numa_masks; +int __read_mostly node_reclaim_distance = RECLAIM_DISTANCE; #endif /* @@ -1410,7 +1411,7 @@ sd_init(struct sched_domain_topology_level *tl, sd->flags &= ~SD_PREFER_SIBLING; sd->flags |= SD_SERIALIZE; - if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) { + if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) { sd->flags &= ~(SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE); diff --git a/mm/khugepaged.c b/mm/khugepaged.c index a335f7c1fac4..67f5f09d70ed 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -710,7 +710,7 @@ static bool khugepaged_scan_abort(int nid) for (i = 0; i < MAX_NUMNODES; i++) { if (!khugepaged_node_load[i]) continue; - if (node_distance(nid, i) > RECLAIM_DISTANCE) + if (node_distance(nid, i) > node_reclaim_distance) return true; } return false; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d66bc8abe0af..8ccaaf3a47f2 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3450,7 +3450,7 @@ bool zone_watermark_ok_safe(struct zone *z, unsigned int order, static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone) { return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <= - RECLAIM_DISTANCE; + node_reclaim_distance; } #else /* CONFIG_NUMA */ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
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