Re: [PATCH v4 1/4] memblock tests: add simulation of physical memory with multiple NUMA nodes

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On 04.09.22 06:21, Rebecca Mckeever wrote:
Add function setup_numa_memblock() for setting up a memory layout with
multiple NUMA nodes in a previously allocated dummy physical memory.
This function can be used in place of setup_memblock() in tests that need
to simulate a NUMA system.

setup_numa_memblock():
- allows for setting up a memory layout by specifying the fraction of
   MEM_SIZE in each node

Set CONFIG_NODES_SHIFT to 4 when building with NUMA=1 to allow for up to
16 NUMA nodes.

Signed-off-by: Rebecca Mckeever <remckee0@xxxxxxxxx>
---
  .../testing/memblock/scripts/Makefile.include |  2 +-
  tools/testing/memblock/tests/common.c         | 29 +++++++++++++++++++
  tools/testing/memblock/tests/common.h         |  4 ++-
  3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/tools/testing/memblock/scripts/Makefile.include b/tools/testing/memblock/scripts/Makefile.include
index aa6d82d56a23..998281723590 100644
--- a/tools/testing/memblock/scripts/Makefile.include
+++ b/tools/testing/memblock/scripts/Makefile.include
@@ -3,7 +3,7 @@
# Simulate CONFIG_NUMA=y
  ifeq ($(NUMA), 1)
-	CFLAGS += -D CONFIG_NUMA
+	CFLAGS += -D CONFIG_NUMA -D CONFIG_NODES_SHIFT=4
  endif
# Use 32 bit physical addresses.
diff --git a/tools/testing/memblock/tests/common.c b/tools/testing/memblock/tests/common.c
index eec6901081af..b6110df21b2a 100644
--- a/tools/testing/memblock/tests/common.c
+++ b/tools/testing/memblock/tests/common.c
@@ -72,6 +72,35 @@ void setup_memblock(void)
  	fill_memblock();
  }
+/**
+ * setup_numa_memblock:
+ * Set up a memory layout with multiple NUMA nodes in a previously allocated
+ * dummy physical memory.
+ * @nodes: an array containing the denominators of the fractions of MEM_SIZE
+ *         contained in each node (e.g., if nodes[0] = SZ_8, node 0 will
+ *         contain 1/8th of MEM_SIZE)
+ *
+ * The nids will be set to 0 through NUMA_NODES - 1.
+ */
+void setup_numa_memblock(const phys_addr_t nodes[])
+{
+	phys_addr_t base;
+	int flags;
+
+	reset_memblock_regions();
+	base = (phys_addr_t)memory_block.base;
+	flags = (movable_node_is_enabled()) ? MEMBLOCK_NONE : MEMBLOCK_HOTPLUG;
+
+	for (int i = 0; i < NUMA_NODES; i++) {
+		assert(nodes[i] <= MEM_SIZE && nodes[i] > 0);

I think it would be even easier to get if this would just be a fraction.
E.g., instead of "1/8 * MEM_SIZE" just "1/8". All values have to add up to 1.

... but then we'd have to mess with floats eventually, so I guess this makes it easier to handle these fractions.


We could use "int" and simply specify the fraction in percent, like

nodes[0] = 50;
nodes[1] = 25;
nodes[2] = 25;

and everything has to add up to 100.


+		phys_addr_t size = MEM_SIZE / nodes[i];


Hmmm, assuming a single node with "MEM_SIZE", we would get size=1.

Shouldn't this be "size = nodes[i]"

?

--
Thanks,

David / dhildenb





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