[PATCH 4/7] genirq/affinity: rename irq_build_affinity_masks as group_cpus_evenly

Ming Lei
2021-08-14T12:36:21Z

Map irq vector into group, so we can abstract the algorithm for generic
use case.

Rename irq_build_affinity_masks as group_cpus_evenly, so we can reuse
the API for blk-mq to make default queue mapping.

No functional change, just rename vector as group.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
kernel/irq/affinity.c | 241 +++++++++++++++++++++---------------------
1 file changed, 121 insertions(+), 120 deletions(-)

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index aef12ec05dcf..ad0ce4b5a28e 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -9,13 +9,13 @@
#include <linux/cpu.h>
#include <linux/sort.h>

-static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
- unsigned int cpus_per_vec)
+static void grp_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
+ unsigned int cpus_per_grp)
{
const struct cpumask *siblmsk;
int cpu, sibl;

- for ( ; cpus_per_vec > 0; ) {
+ for ( ; cpus_per_grp > 0; ) {
cpu = cpumask_first(nmsk);

/* Should not happen, but I'm too lazy to think about it */
@@ -24,18 +24,18 @@ static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,

cpumask_clear_cpu(cpu, nmsk);
cpumask_set_cpu(cpu, irqmsk);
- cpus_per_vec--;
+ cpus_per_grp--;

/* If the cpu has siblings, use them first */
siblmsk = topology_sibling_cpumask(cpu);
- for (sibl = -1; cpus_per_vec > 0; ) {
+ for (sibl = -1; cpus_per_grp > 0; ) {
sibl = cpumask_next(sibl, siblmsk);
if (sibl >= nr_cpu_ids)
break;
if (!cpumask_test_and_clear_cpu(sibl, nmsk))
continue;
cpumask_set_cpu(sibl, irqmsk);
- cpus_per_vec--;
+ cpus_per_grp--;
}
}
}
@@ -95,48 +95,48 @@ static int get_nodes_in_cpumask(cpumask_var_t *node_to_cpumask,
return nodes;
}

-struct node_vectors {
+struct node_groups {
unsigned id;

union {
- unsigned nvectors;
+ unsigned ngroups;
unsigned ncpus;
};
};

static int ncpus_cmp_func(const void *l, const void *r)
{
- const struct node_vectors *ln = l;
- const struct node_vectors *rn = r;
+ const struct node_groups *ln = l;
+ const struct node_groups *rn = r;

return ln->ncpus - rn->ncpus;
}

/*
- * Allocate vector number for each node, so that for each node:
+ * Allocate group number for each node, so that for each node:
*
* 1) the allocated number is >= 1
*
- * 2) the allocated numbver is <= active CPU number of this node
+ * 2) the allocated number is <= active CPU number of this node
*
- * The actual allocated total vectors may be less than @numvecs when
- * active total CPU number is less than @numvecs.
+ * The actual allocated total groups may be less than @numgrps when
+ * active total CPU number is less than @numgrps.
*
* Active CPUs means the CPUs in '@cpu_mask AND @node_to_cpumask[]'
* for each node.
*/
-static void alloc_nodes_vectors(unsigned int numvecs,
- cpumask_var_t *node_to_cpumask,
- const struct cpumask *cpu_mask,
- const nodemask_t nodemsk,
- struct cpumask *nmsk,
- struct node_vectors *node_vectors)
+static void alloc_nodes_groups(unsigned int numgrps,
+ cpumask_var_t *node_to_cpumask,
+ const struct cpumask *cpu_mask,
+ const nodemask_t nodemsk,
+ struct cpumask *nmsk,
+ struct node_groups *node_groups)
{
unsigned n, remaining_ncpus = 0;

for (n = 0; n < nr_node_ids; n++) {
- node_vectors[n].id = n;
- node_vectors[n].ncpus = UINT_MAX;
+ node_groups[n].id = n;
+ node_groups[n].ncpus = UINT_MAX;
}

for_each_node_mask(n, nodemsk) {
@@ -148,61 +148,61 @@ static void alloc_nodes_vectors(unsigned int numvecs,
if (!ncpus)
continue;
remaining_ncpus += ncpus;
- node_vectors[n].ncpus = ncpus;
+ node_groups[n].ncpus = ncpus;
}

- numvecs = min_t(unsigned, remaining_ncpus, numvecs);
+ numgrps = min_t(unsigned, remaining_ncpus, numgrps);

- sort(node_vectors, nr_node_ids, sizeof(node_vectors[0]),
+ sort(node_groups, nr_node_ids, sizeof(node_groups[0]),
ncpus_cmp_func, NULL);

/*
- * Allocate vectors for each node according to the ratio of this
- * node's nr_cpus to remaining un-assigned ncpus. 'numvecs' is
+ * Allocate groups for each node according to the ratio of this
+ * node's nr_cpus to remaining un-assigned ncpus. 'numgrps' is
* bigger than number of active numa nodes. Always start the
* allocation from the node with minimized nr_cpus.
*
* This way guarantees that each active node gets allocated at
- * least one vector, and the theory is simple: over-allocation
- * is only done when this node is assigned by one vector, so
- * other nodes will be allocated >= 1 vector, since 'numvecs' is
+ * least one group, and the theory is simple: over-allocation
+ * is only done when this node is assigned by one group, so
+ * other nodes will be allocated >= 1 groups, since 'numgrps' is
* bigger than number of numa nodes.
*
- * One perfect invariant is that number of allocated vectors for
+ * One perfect invariant is that number of allocated groups for
* each node is <= CPU count of this node:
*
* 1) suppose there are two nodes: A and B
* ncpu(X) is CPU count of node X
- * vecs(X) is the vector count allocated to node X via this
+ * grps(X) is the group count allocated to node X via this
* algorithm
*
* ncpu(A) <= ncpu(B)
* ncpu(A) + ncpu(B) = N
- * vecs(A) + vecs(B) = V
+ * grps(A) + grps(B) = G
*
- * vecs(A) = max(1, round_down(V * ncpu(A) / N))
- * vecs(B) = V - vecs(A)
+ * grps(A) = max(1, round_down(G * ncpu(A) / N))
+ * grps(B) = G - grps(A)
*
- * both N and V are integer, and 2 <= V <= N, suppose
- * V = N - delta, and 0 <= delta <= N - 2
+ * both N and G are integer, and 2 <= G <= N, suppose
+ * G = N - delta, and 0 <= delta <= N - 2
*
- * 2) obviously vecs(A) <= ncpu(A) because:
+ * 2) obviously grps(A) <= ncpu(A) because:
*
- * if vecs(A) is 1, then vecs(A) <= ncpu(A) given
+ * if grps(A) is 1, then grps(A) <= ncpu(A) given
* ncpu(A) >= 1
*
* otherwise,
- * vecs(A) <= V * ncpu(A) / N <= ncpu(A), given V <= N
+ * grps(A) <= G * ncpu(A) / N <= ncpu(A), given G <= N
*
- * 3) prove how vecs(B) <= ncpu(B):
+ * 3) prove how grps(B) <= ncpu(B):
*
- * if round_down(V * ncpu(A) / N) == 0, vecs(B) won't be
- * over-allocated, so vecs(B) <= ncpu(B),
+ * if round_down(G * ncpu(A) / N) == 0, vecs(B) won't be
+ * over-allocated, so grps(B) <= ncpu(B),
*
* otherwise:
*
- * vecs(A) =
- * round_down(V * ncpu(A) / N) =
+ * grps(A) =
+ * round_down(G * ncpu(A) / N) =
* round_down((N - delta) * ncpu(A) / N) =
* round_down((N * ncpu(A) - delta * ncpu(A)) / N) >=
* round_down((N * ncpu(A) - delta * N) / N) =
@@ -210,52 +210,50 @@ static void alloc_nodes_vectors(unsigned int numvecs,
*
* then:
*
- * vecs(A) - V >= ncpu(A) - delta - V
+ * grps(A) - G >= ncpu(A) - delta - G
* =>
- * V - vecs(A) <= V + delta - ncpu(A)
+ * G - grps(A) <= G + delta - ncpu(A)
* =>
- * vecs(B) <= N - ncpu(A)
+ * grps(B) <= N - ncpu(A)
* =>
- * vecs(B) <= cpu(B)
+ * grps(B) <= cpu(B)
*
* For nodes >= 3, it can be thought as one node and another big
* node given that is exactly what this algorithm is implemented,
- * and we always re-calculate 'remaining_ncpus' & 'numvecs', and
- * finally for each node X: vecs(X) <= ncpu(X).
+ * and we always re-calculate 'remaining_ncpus' & 'numgrps', and
+ * finally for each node X: grps(X) <= ncpu(X).
*
*/
for (n = 0; n < nr_node_ids; n++) {
- unsigned nvectors, ncpus;
+ unsigned ngroups, ncpus;

- if (node_vectors[n].ncpus == UINT_MAX)
+ if (node_groups[n].ncpus == UINT_MAX)
continue;

- WARN_ON_ONCE(numvecs == 0);
+ WARN_ON_ONCE(numgrps == 0);

- ncpus = node_vectors[n].ncpus;
- nvectors = max_t(unsigned, 1,
- numvecs * ncpus / remaining_ncpus);
- WARN_ON_ONCE(nvectors > ncpus);
+ ncpus = node_groups[n].ncpus;
+ ngroups = max_t(unsigned, 1,
+ numgrps * ncpus / remaining_ncpus);
+ WARN_ON_ONCE(ngroups > ncpus);

- node_vectors[n].nvectors = nvectors;
+ node_groups[n].ngroups = ngroups;

remaining_ncpus -= ncpus;
- numvecs -= nvectors;
+ numgrps -= ngroups;
}
}

-static int __irq_build_affinity_masks(unsigned int startvec,
- unsigned int numvecs,
- cpumask_var_t *node_to_cpumask,
- const struct cpumask *cpu_mask,
- struct cpumask *nmsk,
- struct cpumask *masks)
+static int __group_cpus_evenly(unsigned int startgrp, unsigned int numgrps,
+ cpumask_var_t *node_to_cpumask,
+ const struct cpumask *cpu_mask,
+ struct cpumask *nmsk, struct cpumask *masks)
{
- unsigned int i, n, nodes, cpus_per_vec, extra_vecs, done = 0;
- unsigned int last_affv = numvecs;
- unsigned int curvec = startvec;
+ unsigned int i, n, nodes, cpus_per_grp, extra_grps, done = 0;
+ unsigned int last_grp = numgrps;
+ unsigned int curgrp = startgrp;
nodemask_t nodemsk = NODE_MASK_NONE;
- struct node_vectors *node_vectors;
+ struct node_groups *node_groups;

if (!cpumask_weight(cpu_mask))
return 0;
@@ -264,33 +262,33 @@ static int __irq_build_affinity_masks(unsigned int startvec,

/*
* If the number of nodes in the mask is greater than or equal the
- * number of vectors we just spread the vectors across the nodes.
+ * number of groups we just spread the groups across the nodes.
*/
- if (numvecs <= nodes) {
+ if (numgrps <= nodes) {
for_each_node_mask(n, nodemsk) {
- cpumask_or(&masks[curvec], &masks[curvec],
+ cpumask_or(&masks[curgrp], &masks[curgrp],
node_to_cpumask[n]);
- if (++curvec == last_affv)
- curvec = 0;
+ if (++curgrp == last_grp)
+ curgrp = 0;
}
- return numvecs;
+ return numgrps;
}

- node_vectors = kcalloc(nr_node_ids,
- sizeof(struct node_vectors),
+ node_groups = kcalloc(nr_node_ids,
+ sizeof(struct node_groups),
GFP_KERNEL);
- if (!node_vectors)
+ if (!node_groups)
return -ENOMEM;

- /* allocate vector number for each node */
- alloc_nodes_vectors(numvecs, node_to_cpumask, cpu_mask,
- nodemsk, nmsk, node_vectors);
+ /* allocate group number for each node */
+ alloc_nodes_groups(numgrps, node_to_cpumask, cpu_mask,
+ nodemsk, nmsk, node_groups);

for (i = 0; i < nr_node_ids; i++) {
unsigned int ncpus, v;
- struct node_vectors *nv = &node_vectors[i];
+ struct node_groups *nv = &node_groups[i];

- if (nv->nvectors == UINT_MAX)
+ if (nv->ngroups == UINT_MAX)
continue;

/* Get the cpus on this node which are in the mask */
@@ -299,44 +297,47 @@ static int __irq_build_affinity_masks(unsigned int startvec,
if (!ncpus)
continue;

- WARN_ON_ONCE(nv->nvectors > ncpus);
+ WARN_ON_ONCE(nv->ngroups > ncpus);

/* Account for rounding errors */
- extra_vecs = ncpus - nv->nvectors * (ncpus / nv->nvectors);
+ extra_grps = ncpus - nv->ngroups * (ncpus / nv->ngroups);

- /* Spread allocated vectors on CPUs of the current node */
- for (v = 0; v < nv->nvectors; v++, curvec++) {
- cpus_per_vec = ncpus / nv->nvectors;
+ /* Spread allocated groups on CPUs of the current node */
+ for (v = 0; v < nv->ngroups; v++, curgrp++) {
+ cpus_per_grp = ncpus / nv->ngroups;

- /* Account for extra vectors to compensate rounding errors */
- if (extra_vecs) {
- cpus_per_vec++;
- --extra_vecs;
+ /* Account for extra groups to compensate rounding errors */
+ if (extra_grps) {
+ cpus_per_grp++;
+ --extra_grps;
}

/*
- * wrapping has to be considered given 'startvec'
+ * wrapping has to be considered given 'startgrp'
* may start anywhere
*/
- if (curvec >= last_affv)
- curvec = 0;
- irq_spread_init_one(&masks[curvec], nmsk,
- cpus_per_vec);
+ if (curgrp >= last_grp)
+ curgrp = 0;
+ grp_spread_init_one(&masks[curgrp], nmsk,
+ cpus_per_grp);
}
- done += nv->nvectors;
+ done += nv->ngroups;
}
- kfree(node_vectors);
+ kfree(node_groups);
return done;
}

/*
- * build affinity in two stages:
- * 1) spread present CPU on these vectors
- * 2) spread other possible CPUs on these vectors
+ * build affinity in two stages for each group, and try to put close CPUs
+ * in viewpoint of CPU and NUMA locality into same group, and we run
+ * two-stage grouping:
+ *
+ * 1) allocate present CPUs on these groups evenly first
+ * 2) allocate other possible CPUs on these groups evenly
*/
-static struct cpumask *irq_build_affinity_masks(unsigned int numvecs)
+static struct cpumask *group_cpus_evenly(unsigned int numgrps)
{
- unsigned int curvec = 0, nr_present = 0, nr_others = 0;
+ unsigned int curgrp = 0, nr_present = 0, nr_others = 0;
cpumask_var_t *node_to_cpumask;
cpumask_var_t nmsk, npresmsk;
int ret = -ENOMEM;
@@ -352,7 +353,7 @@ static struct cpumask *irq_build_affinity_masks(unsigned int numvecs)
if (!node_to_cpumask)
goto fail_npresmsk;

- masks = kcalloc(numvecs, sizeof(*masks), GFP_KERNEL);
+ masks = kcalloc(numgrps, sizeof(*masks), GFP_KERNEL);
if (!masks)
goto fail_node_to_cpumask;

@@ -360,26 +361,26 @@ static struct cpumask *irq_build_affinity_masks(unsigned int numvecs)
cpus_read_lock();
build_node_to_cpumask(node_to_cpumask);

- /* Spread on present CPUs starting from affd->pre_vectors */
- ret = __irq_build_affinity_masks(curvec, numvecs, node_to_cpumask,
- cpu_present_mask, nmsk, masks);
+ /* grouping present CPUs first */
+ ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask,
+ cpu_present_mask, nmsk, masks);
if (ret < 0)
goto fail_build_affinity;
nr_present = ret;

/*
- * Spread on non present CPUs starting from the next vector to be
- * handled. If the spreading of present CPUs already exhausted the
- * vector space, assign the non present CPUs to the already spread
- * out vectors.
+ * Allocate non present CPUs starting from the next group to be
+ * handled. If the grouping of present CPUs already exhausted the
+ * group space, assign the non present CPUs to the already
+ * allocated out groups.
*/
- if (nr_present >= numvecs)
- curvec = 0;
+ if (nr_present >= numgrps)
+ curgrp = 0;
else
- curvec = nr_present;
+ curgrp = nr_present;
cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
- ret = __irq_build_affinity_masks(curvec, numvecs, node_to_cpumask,
- npresmsk, nmsk, masks);
+ ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask,
+ npresmsk, nmsk, masks);
if (ret >= 0)
nr_others = ret;

@@ -387,7 +388,7 @@ static struct cpumask *irq_build_affinity_masks(unsigned int numvecs)
cpus_read_unlock();

if (ret >= 0)
- WARN_ON(nr_present + nr_others < numvecs);
+ WARN_ON(nr_present + nr_others < numgrps);

fail_node_to_cpumask:
free_node_to_cpumask(node_to_cpumask);
@@ -466,7 +467,7 @@ irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
unsigned int this_vecs = affd->set_size[i];
int j;
- struct cpumask *result = irq_build_affinity_masks(this_vecs);
+ struct cpumask *result = group_cpus_evenly(this_vecs);

if (!result) {
kfree(masks);
--
2.31.1