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SubjectRe: [PATCH v4 1/4] memblock tests: add simulation of physical memory with multiple NUMA nodes
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@gmail.com>
> ---
> .../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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