[PATCH v5 4/6] powerpc/pseries: Consolidate different NUMA distance update code paths
Aneesh Kumar K.V
aneesh.kumar at linux.ibm.com
Tue Jul 27 13:32:33 AEST 2021
David Gibson <david at gibson.dropbear.id.au> writes:
> On Thu, Jul 22, 2021 at 12:37:46PM +0530, Aneesh Kumar K.V wrote:
>> David Gibson <david at gibson.dropbear.id.au> writes:
>>
>> > On Mon, Jun 28, 2021 at 08:41:15PM +0530, Aneesh Kumar K.V wrote:
....
>
>> >
>> >> + nid = of_read_number(&aa.arrays[index], 1);
>> >> +
>> >> + if (nid == 0xffff || nid >= nr_node_ids)
>> >> + nid = default_nid;
>> >> + if (nid > 0 && affinity_form == FORM1_AFFINITY) {
>> >> + int i;
>> >> + const __be32 *associativity;
>> >> +
>> >> + index = lmb->aa_index * aa.array_sz;
>> >> + associativity = &aa.arrays[index];
>> >> + /*
>> >> + * lookup array associativity entries have different format
>> >> + * There is no length of the array as the first element.
>> >
>> > The difference it very small, and this is not a hot path. Couldn't
>> > you reduce a chunk of code by prepending aa.array_sz, then re-using
>> > __initialize_form1_numa_distance. Or even making
>> > __initialize_form1_numa_distance() take the length as a parameter.
>>
>> The changes are small but confusing w.r.t how we look at the
>> associativity-lookup-arrays. The way we interpret associativity array
>> and associativity lookup array using primary_domain_index is different.
>> Hence the '-1' in the node lookup here.
>
> They're really not, though. It's exactly the same interpretation of
> the associativity array itself - it's just that one of them has the
> array prepended with a (redundant) length. So you can make
> __initialize_form1_numa_distance() work on the "bare" associativity
> array, with a given length. Here you call it with aa.array_sz as the
> length, and in the other place you call it with prop[0] as the length.
>
>>
>> index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;
>> nid = of_read_number(&aa.arrays[index], 1);
>>
>>
>> >
>> >> + */
>> >> + for (i = 0; i < max_associativity_domain_index; i++) {
>> >> + const __be32 *entry;
>> >> +
>> >> + entry = &associativity[be32_to_cpu(distance_ref_points[i]) - 1];
>> >
>> > Does anywhere verify that distance_ref_points[i] <= aa.array_size for
>> > every i?
>>
>> We do check for
>>
>> if (primary_domain_index <= aa.array_sz &&
>
> Right, but that doesn't check the other distance_ref_points entries.
> Not that there's any reason to have extra entries with Form2, but we
> still don't want stray array accesses.
This is how the change looks. I am not convinced this makes it simpler.
I will add that as the last patch and we can drop that if we find that
not helpful?
modified arch/powerpc/mm/numa.c
@@ -171,20 +171,31 @@ static void unmap_cpu_from_node(unsigned long cpu)
}
#endif /* CONFIG_HOTPLUG_CPU || CONFIG_PPC_SPLPAR */
-/*
- * Returns nid in the range [0..nr_node_ids], or -1 if no useful NUMA
- * info is found.
- */
-static int associativity_to_nid(const __be32 *associativity)
+static int __associativity_to_nid(const __be32 *associativity,
+ bool lookup_array_assoc,
+ int max_array_index)
{
int nid = NUMA_NO_NODE;
+ int index;
if (!numa_enabled)
goto out;
+ /*
+ * ibm,associativity-lookup-array doesn't have element
+ * count at the start of the associativity. Hence
+ * decrement the primary_domain_index when used with
+ * lookup-array associativity.
+ */
+ if (lookup_array_assoc)
+ index = primary_domain_index - 1;
+ else {
+ index = primary_domain_index;
+ max_array_index = of_read_number(associativity, 1);
+ }
+ if (index > max_array_index)
+ goto out;
- if (of_read_number(associativity, 1) >= primary_domain_index)
- nid = of_read_number(&associativity[primary_domain_index], 1);
-
+ nid = of_read_number(&associativity[index], 1);
/* POWER4 LPAR uses 0xffff as invalid node */
if (nid == 0xffff || nid >= nr_node_ids)
nid = NUMA_NO_NODE;
@@ -192,6 +203,15 @@ static int associativity_to_nid(const __be32 *associativity)
return nid;
}
+/*
+ * Returns nid in the range [0..nr_node_ids], or -1 if no useful NUMA
+ * info is found.
+ */
+static inline int associativity_to_nid(const __be32 *associativity)
+{
+ return __associativity_to_nid(associativity, false, 0);
+}
+
static int __cpu_form2_relative_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
{
int dist;
@@ -295,19 +315,38 @@ int of_node_to_nid(struct device_node *device)
}
EXPORT_SYMBOL(of_node_to_nid);
-static void __initialize_form1_numa_distance(const __be32 *associativity)
+static void __initialize_form1_numa_distance(const __be32 *associativity,
+ bool lookup_array_assoc,
+ int max_array_index)
{
int i, nid;
+ int index_offset = 0;
if (affinity_form != FORM1_AFFINITY)
return;
+ /*
+ * ibm,associativity-lookup-array doesn't have element
+ * count at the start of the associativity. Hence
+ * decrement the distance_ref_points index when used with
+ * lookup-array associativity.
+ */
+ if (lookup_array_assoc)
+ index_offset = 1;
+ else
+ max_array_index = of_read_number(associativity, 1);
- nid = associativity_to_nid(associativity);
+ nid = __associativity_to_nid(associativity, lookup_array_assoc, max_array_index);
if (nid != NUMA_NO_NODE) {
for (i = 0; i < distance_ref_points_depth; i++) {
const __be32 *entry;
+ int index = be32_to_cpu(distance_ref_points[i]) - index_offset;
- entry = &associativity[be32_to_cpu(distance_ref_points[i])];
+ /*
+ * broken hierarchy, return with broken distance table
+ */
+ if (index > max_array_index)
+ return;
+ entry = &associativity[index];
distance_lookup_table[nid][i] = of_read_number(entry, 1);
}
}
@@ -321,7 +360,7 @@ static void initialize_form1_numa_distance(struct device_node *node)
if (!associativity)
return;
- __initialize_form1_numa_distance(associativity);
+ __initialize_form1_numa_distance(associativity, false, 0);
}
/*
@@ -586,27 +625,14 @@ static int get_nid_and_numa_distance(struct drmem_lmb *lmb)
if (primary_domain_index <= aa.array_sz &&
!(lmb->flags & DRCONF_MEM_AI_INVALID) && lmb->aa_index < aa.n_arrays) {
- index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;
- nid = of_read_number(&aa.arrays[index], 1);
+ const __be32 *associativity;
- if (nid == 0xffff || nid >= nr_node_ids)
- nid = default_nid;
+ index = lmb->aa_index * aa.array_sz;
+ associativity = &aa.arrays[index];
+ nid = __associativity_to_nid(associativity, true, aa.array_sz - 1);
if (nid > 0 && affinity_form == FORM1_AFFINITY) {
- int i;
- const __be32 *associativity;
-
- index = lmb->aa_index * aa.array_sz;
- associativity = &aa.arrays[index];
- /*
- * lookup array associativity entries have different format
- * There is no length of the array as the first element.
- */
- for (i = 0; i < distance_ref_points_depth; i++) {
- const __be32 *entry;
-
- entry = &associativity[be32_to_cpu(distance_ref_points[i]) - 1];
- distance_lookup_table[nid][i] = of_read_number(entry, 1);
- }
+ __initialize_form1_numa_distance(associativity,
+ true, aa.array_sz - 1);
}
}
return nid;
@@ -632,9 +658,11 @@ int of_drconf_to_nid_single(struct drmem_lmb *lmb)
if (primary_domain_index <= aa.array_sz &&
!(lmb->flags & DRCONF_MEM_AI_INVALID) && lmb->aa_index < aa.n_arrays) {
- index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;
- nid = of_read_number(&aa.arrays[index], 1);
+ const __be32 *associativity;
+ index = lmb->aa_index * aa.array_sz;
+ associativity = &aa.arrays[index];
+ nid = __associativity_to_nid(associativity, true, aa.array_sz - 1);
if (nid == 0xffff || nid >= nr_node_ids)
nid = default_nid;
}
@@ -939,7 +967,7 @@ static int __init parse_numa_properties(void)
if (__vphn_get_associativity(i, vphn_assoc) == 0) {
nid = associativity_to_nid(vphn_assoc);
- __initialize_form1_numa_distance(vphn_assoc);
+ __initialize_form1_numa_distance(vphn_assoc, false, 0);
} else {
/*
@@ -953,7 +981,7 @@ static int __init parse_numa_properties(void)
associativity = of_get_associativity(cpu);
if (associativity) {
nid = associativity_to_nid(associativity);
- __initialize_form1_numa_distance(associativity);
+ __initialize_form1_numa_distance(associativity, false, 0);
}
of_node_put(cpu);
}
@@ -993,7 +1021,7 @@ static int __init parse_numa_properties(void)
associativity = of_get_associativity(memory);
if (associativity) {
nid = associativity_to_nid(associativity);
- __initialize_form1_numa_distance(associativity);
+ __initialize_form1_numa_distance(associativity, false, 0);
} else
nid = default_nid;
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