Re: [PATCH] arm64: numa: rightsize the distance array
From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Date: 2020-07-24 11:05:11
Also in:
linux-acpi
On Wed, 8 Jul 2020 19:38:25 +0800 Jonathan Cameron [off-list ref] wrote:
Unfortunately we are currently calling numa_alloc_distance well before we call setup_node_to_cpu_mask_map means that nr_node_ids is set to MAX_NUMNODES. This wastes a bit of memory and is confusing to the reader. Note we could just decide to hardcode it as MAX_NUMNODES but if so we should do so explicitly. Looking at what x86 does, they do a walk of nodes_parsed and locally establish the maximum node count seen. We can't actually do that where we were previously calling it in numa_init because nodes_parsed isn't set up either yet. So let us take a leaf entirely out of x86's book and make the true assumption that nodes_parsed will definitely be set up before we try to put a real value in this array. Hence just do it on demand. In order to avoid trying and failing to allocate the array multiple times we do the same thing as x86 and set numa_distance = 1. This requires a few small modifications elsewhere. Worth noting, that with one exception (which it appears can be removed [1]) the x86 and arm numa distance code is now identical. Worth factoring it out to some common location? [1] https://lkml.kernel.org/r/20170406124459.dwn5zhpr2xqg3lqm@node.shutemov.name Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Polite nudge. Anyone? No particular urgency on this one but I'm thinking of taking a stab at factoring out this code into a common location for arm64 and x86 and this change needs to proceed that. Thanks, Jonathan
quoted hunk ↗ jump to hunk
--- arch/arm64/mm/numa.c | 35 ++++++++++++++++++----------------- 1 file changed, 18 insertions(+), 17 deletions(-)diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c index aafcee3e3f7e..a2f549ef0a36 100644 --- a/arch/arm64/mm/numa.c +++ b/arch/arm64/mm/numa.c@@ -255,13 +255,11 @@ void __init numa_free_distance(void) { size_t size; - if (!numa_distance) - return; - size = numa_distance_cnt * numa_distance_cnt * sizeof(numa_distance[0]); - - memblock_free(__pa(numa_distance), size); + /* numa_distance could be 1LU marking allocation failure, test cnt */ + if (numa_distance_cnt) + memblock_free(__pa(numa_distance), size); numa_distance_cnt = 0; numa_distance = NULL; }@@ -271,20 +269,29 @@ void __init numa_free_distance(void) */ static int __init numa_alloc_distance(void) { + nodemask_t nodes_parsed; size_t size; + int i, j, cnt = 0; u64 phys; - int i, j; - size = nr_node_ids * nr_node_ids * sizeof(numa_distance[0]); + /* size the new table and allocate it */ + nodes_parsed = numa_nodes_parsed; + for_each_node_mask(i, nodes_parsed) + cnt = i; + cnt++; + size = cnt * cnt * sizeof(numa_distance[0]); phys = memblock_find_in_range(0, PFN_PHYS(max_pfn), size, PAGE_SIZE); - if (WARN_ON(!phys)) + if (!phys) { + pr_warn("Warning: can't allocate distance table!\n"); + /* don't retry until explicitly reset */ + numa_distance = (void *)1LU; return -ENOMEM; - + } memblock_reserve(phys, size); numa_distance = __va(phys); - numa_distance_cnt = nr_node_ids; + numa_distance_cnt = cnt; /* fill with the default distances */ for (i = 0; i < numa_distance_cnt; i++)@@ -311,10 +318,8 @@ static int __init numa_alloc_distance(void) */ void __init numa_set_distance(int from, int to, int distance) { - if (!numa_distance) { - pr_warn_once("Warning: distance table not allocated yet\n"); + if (!numa_distance && numa_alloc_distance() < 0) return; - } if (from >= numa_distance_cnt || to >= numa_distance_cnt || from < 0 || to < 0) {@@ -384,10 +389,6 @@ static int __init numa_init(int (*init_func)(void)) nodes_clear(node_possible_map); nodes_clear(node_online_map); - ret = numa_alloc_distance(); - if (ret < 0) - return ret; - ret = init_func(); if (ret < 0) goto out_free_distance;
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