On 14/12/2020 10:51, Chris Wilson wrote:
Refactor the allocation such that we utilise just enough memory pressure
to invoke the shrinker, and just enough processes to spread across the
CPUs and contend on the shrinker.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
tests/i915/gem_shrink.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/tests/i915/gem_shrink.c b/tests/i915/gem_shrink.c
index 023db8c56..e8a814fe6 100644
--- a/tests/i915/gem_shrink.c
+++ b/tests/i915/gem_shrink.c
@@ -426,6 +426,7 @@ igt_main
int num_processes = 0;
igt_fixture {
+ const int ncpus = sysconf(_SC_NPROCESSORS_ONLN);
uint64_t mem_size = intel_get_total_ram_mb();
int fd;
@@ -434,16 +435,16 @@ igt_main
/*
* Spawn enough processes to use all memory, but each only
- * uses half the available mappable aperture ~128MiB.
+ * uses half of the available per-cpu memory.
* Individually the processes would be ok, but en masse
* we expect the shrinker to start purging objects,
* and possibly fail.
*/
- alloc_size = gem_mappable_aperture_size(fd) / 2;
- num_processes = 1 + (mem_size / (alloc_size >> 20));
+ alloc_size = (mem_size + ncpus - 1) / ncpus / 2;
Div round up with thousands divided by small integers okay, safe on very
old smp boxes. :)
+ num_processes = ncpus + (mem_size / alloc_size);
Hm, now what does this add up to..
ncpus + mem_size / (mem_size / ncpus / 2) = ... ?
Regards,
Tvrtko
- igt_info("Using %d processes and %'lluMiB per process\n",
- num_processes, (long long)(alloc_size >> 20));
+ igt_info("Using %d processes and %'"PRIu64"MiB per process\n",
+ num_processes, alloc_size);
intel_require_memory(num_processes, alloc_size,
CHECK_SWAP | CHECK_RAM);
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