From 43245117806ff8914e37327b610fc08b5ddedc91 Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:28 -0800 Subject: lib/find: introduce find_nth_and_andnot_bit In the following patches the function is used to implement in-place bitmaps traversing without storing intermediate result in temporary bitmaps. Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- include/linux/find.h | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'include/linux') diff --git a/include/linux/find.h b/include/linux/find.h index ccaf61a0f5fd..4647864a5ffd 100644 --- a/include/linux/find.h +++ b/include/linux/find.h @@ -22,6 +22,9 @@ unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long unsigned long size, unsigned long n); unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long size, unsigned long n); +unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, + const unsigned long *addr3, unsigned long size, + unsigned long n); extern unsigned long _find_first_and_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long size); extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size); @@ -255,6 +258,36 @@ unsigned long find_nth_andnot_bit(const unsigned long *addr1, const unsigned lon return __find_nth_andnot_bit(addr1, addr2, size, n); } +/** + * find_nth_and_andnot_bit - find N'th set bit in 2 memory regions, + * excluding those set in 3rd region + * @addr1: The 1st address to start the search at + * @addr2: The 2nd address to start the search at + * @addr3: The 3rd address to start the search at + * @size: The maximum number of bits to search + * @n: The number of set bit, which position is needed, counting from 0 + * + * Returns the bit number of the N'th set bit. + * If no such, returns @size. + */ +static __always_inline +unsigned long find_nth_and_andnot_bit(const unsigned long *addr1, + const unsigned long *addr2, + const unsigned long *addr3, + unsigned long size, unsigned long n) +{ + if (n >= size) + return size; + + if (small_const_nbits(size)) { + unsigned long val = *addr1 & *addr2 & (~*addr3) & GENMASK(size - 1, 0); + + return val ? fns(val, n) : size; + } + + return __find_nth_and_andnot_bit(addr1, addr2, addr3, size, n); +} + #ifndef find_first_and_bit /** * find_first_and_bit - find the first set bit in both memory regions -- cgit v1.2.3 From 62f4386e564d31c7d0ed7d835843e2685f99ae71 Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:29 -0800 Subject: cpumask: introduce cpumask_nth_and_andnot Introduce cpumask_nth_and_andnot() based on find_nth_and_andnot_bit(). It's used in the following patch to traverse cpumasks without storing intermediate result in temporary cpumask. Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- include/linux/cpumask.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'include/linux') diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index c2aa0aa26b45..7b16aede7ac5 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -391,6 +391,26 @@ unsigned int cpumask_nth_andnot(unsigned int cpu, const struct cpumask *srcp1, nr_cpumask_bits, cpumask_check(cpu)); } +/** + * cpumask_nth_and_andnot - get the Nth cpu set in 1st and 2nd cpumask, and clear in 3rd. + * @srcp1: the cpumask pointer + * @srcp2: the cpumask pointer + * @srcp3: the cpumask pointer + * @cpu: the N'th cpu to find, starting from 0 + * + * Returns >= nr_cpu_ids if such cpu doesn't exist. + */ +static __always_inline +unsigned int cpumask_nth_and_andnot(unsigned int cpu, const struct cpumask *srcp1, + const struct cpumask *srcp2, + const struct cpumask *srcp3) +{ + return find_nth_and_andnot_bit(cpumask_bits(srcp1), + cpumask_bits(srcp2), + cpumask_bits(srcp3), + nr_cpumask_bits, cpumask_check(cpu)); +} + #define CPU_BITS_NONE \ { \ [0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL \ -- cgit v1.2.3 From cd7f55359c90a4108e6528e326b8623fce1ad72a Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:30 -0800 Subject: sched: add sched_numa_find_nth_cpu() The function finds Nth set CPU in a given cpumask starting from a given node. Leveraging the fact that each hop in sched_domains_numa_masks includes the same or greater number of CPUs than the previous one, we can use binary search on hops instead of linear walk, which makes the overall complexity of O(log n) in terms of number of cpumask_weight() calls. Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- include/linux/topology.h | 8 +++++++ kernel/sched/topology.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 65 insertions(+) (limited to 'include/linux') diff --git a/include/linux/topology.h b/include/linux/topology.h index 4564faafd0e1..72f264575698 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -245,5 +245,13 @@ static inline const struct cpumask *cpu_cpu_mask(int cpu) return cpumask_of_node(cpu_to_node(cpu)); } +#ifdef CONFIG_NUMA +int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node); +#else +static __always_inline int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) +{ + return cpumask_nth(cpu, cpus); +} +#endif /* CONFIG_NUMA */ #endif /* _LINUX_TOPOLOGY_H */ diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 8739c2a5a54e..2bf89186a10f 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -3,6 +3,8 @@ * Scheduler topology setup/handling methods */ +#include + DEFINE_MUTEX(sched_domains_mutex); /* Protected by sched_domains_mutex: */ @@ -2067,6 +2069,61 @@ unlock: return found; } +struct __cmp_key { + const struct cpumask *cpus; + struct cpumask ***masks; + int node; + int cpu; + int w; +}; + +static int hop_cmp(const void *a, const void *b) +{ + struct cpumask **prev_hop = *((struct cpumask ***)b - 1); + struct cpumask **cur_hop = *(struct cpumask ***)b; + struct __cmp_key *k = (struct __cmp_key *)a; + + if (cpumask_weight_and(k->cpus, cur_hop[k->node]) <= k->cpu) + return 1; + + k->w = (b == k->masks) ? 0 : cpumask_weight_and(k->cpus, prev_hop[k->node]); + if (k->w <= k->cpu) + return 0; + + return -1; +} + +/* + * sched_numa_find_nth_cpu() - given the NUMA topology, find the Nth next cpu + * closest to @cpu from @cpumask. + * cpumask: cpumask to find a cpu from + * cpu: Nth cpu to find + * + * returns: cpu, or nr_cpu_ids when nothing found. + */ +int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) +{ + struct __cmp_key k = { .cpus = cpus, .node = node, .cpu = cpu }; + struct cpumask ***hop_masks; + int hop, ret = nr_cpu_ids; + + rcu_read_lock(); + + k.masks = rcu_dereference(sched_domains_numa_masks); + if (!k.masks) + goto unlock; + + hop_masks = bsearch(&k, k.masks, sched_domains_numa_levels, sizeof(k.masks[0]), hop_cmp); + hop = hop_masks - k.masks; + + ret = hop ? + cpumask_nth_and_andnot(cpu - k.w, cpus, k.masks[hop][node], k.masks[hop-1][node]) : + cpumask_nth_and(cpu, cpus, k.masks[0][node]); +unlock: + rcu_read_unlock(); + return ret; +} +EXPORT_SYMBOL_GPL(sched_numa_find_nth_cpu); #endif /* CONFIG_NUMA */ static int __sdt_alloc(const struct cpumask *cpu_map) -- cgit v1.2.3 From 9feae65845f7b16376716fe70b7d4b9bf8721848 Mon Sep 17 00:00:00 2001 From: Valentin Schneider Date: Fri, 20 Jan 2023 20:24:33 -0800 Subject: sched/topology: Introduce sched_numa_hop_mask() Tariq has pointed out that drivers allocating IRQ vectors would benefit from having smarter NUMA-awareness - cpumask_local_spread() only knows about the local node and everything outside is in the same bucket. sched_domains_numa_masks is pretty much what we want to hand out (a cpumask of CPUs reachable within a given distance budget), introduce sched_numa_hop_mask() to export those cpumasks. Link: http://lore.kernel.org/r/20220728191203.4055-1-tariqt@nvidia.com Signed-off-by: Valentin Schneider Reviewed-by: Yury Norov Signed-off-by: Yury Norov Signed-off-by: Jakub Kicinski --- include/linux/topology.h | 7 +++++++ kernel/sched/topology.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) (limited to 'include/linux') diff --git a/include/linux/topology.h b/include/linux/topology.h index 72f264575698..344c2362755a 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -247,11 +247,18 @@ static inline const struct cpumask *cpu_cpu_mask(int cpu) #ifdef CONFIG_NUMA int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node); +extern const struct cpumask *sched_numa_hop_mask(unsigned int node, unsigned int hops); #else static __always_inline int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) { return cpumask_nth(cpu, cpus); } + +static inline const struct cpumask * +sched_numa_hop_mask(unsigned int node, unsigned int hops) +{ + return ERR_PTR(-EOPNOTSUPP); +} #endif /* CONFIG_NUMA */ #endif /* _LINUX_TOPOLOGY_H */ diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 2bf89186a10f..1233affc106c 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -2124,6 +2124,39 @@ unlock: return ret; } EXPORT_SYMBOL_GPL(sched_numa_find_nth_cpu); + +/** + * sched_numa_hop_mask() - Get the cpumask of CPUs at most @hops hops away from + * @node + * @node: The node to count hops from. + * @hops: Include CPUs up to that many hops away. 0 means local node. + * + * Return: On success, a pointer to a cpumask of CPUs at most @hops away from + * @node, an error value otherwise. + * + * Requires rcu_lock to be held. Returned cpumask is only valid within that + * read-side section, copy it if required beyond that. + * + * Note that not all hops are equal in distance; see sched_init_numa() for how + * distances and masks are handled. + * Also note that this is a reflection of sched_domains_numa_masks, which may change + * during the lifetime of the system (offline nodes are taken out of the masks). + */ +const struct cpumask *sched_numa_hop_mask(unsigned int node, unsigned int hops) +{ + struct cpumask ***masks; + + if (node >= nr_node_ids || hops >= sched_domains_numa_levels) + return ERR_PTR(-EINVAL); + + masks = rcu_dereference(sched_domains_numa_masks); + if (!masks) + return ERR_PTR(-EBUSY); + + return masks[hops][node]; +} +EXPORT_SYMBOL_GPL(sched_numa_hop_mask); + #endif /* CONFIG_NUMA */ static int __sdt_alloc(const struct cpumask *cpu_map) -- cgit v1.2.3 From 06ac01721f7d07da722abe0ec6f147b90bfc8c77 Mon Sep 17 00:00:00 2001 From: Valentin Schneider Date: Fri, 20 Jan 2023 20:24:34 -0800 Subject: sched/topology: Introduce for_each_numa_hop_mask() The recently introduced sched_numa_hop_mask() exposes cpumasks of CPUs reachable within a given distance budget, wrap the logic for iterating over all (distance, mask) values inside an iterator macro. Signed-off-by: Valentin Schneider Reviewed-by: Yury Norov Signed-off-by: Yury Norov Signed-off-by: Jakub Kicinski --- include/linux/topology.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'include/linux') diff --git a/include/linux/topology.h b/include/linux/topology.h index 344c2362755a..fea32377f7c7 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -261,4 +261,22 @@ sched_numa_hop_mask(unsigned int node, unsigned int hops) } #endif /* CONFIG_NUMA */ +/** + * for_each_numa_hop_mask - iterate over cpumasks of increasing NUMA distance + * from a given node. + * @mask: the iteration variable. + * @node: the NUMA node to start the search from. + * + * Requires rcu_lock to be held. + * + * Yields cpu_online_mask for @node == NUMA_NO_NODE. + */ +#define for_each_numa_hop_mask(mask, node) \ + for (unsigned int __hops = 0; \ + mask = (node != NUMA_NO_NODE || __hops) ? \ + sched_numa_hop_mask(node, __hops) : \ + cpu_online_mask, \ + !IS_ERR_OR_NULL(mask); \ + __hops++) + #endif /* _LINUX_TOPOLOGY_H */ -- cgit v1.2.3