On 06/02/2024 11:24 am, John Garry wrote:
On 05/02/2024 15:32, Robin Murphy wrote:
From: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
The magazine buffers can take gigabytes of kmem memory, dominating all
other allocations. For observability purpose create named slab cache so
the iova magazine memory overhead can be clearly observed.
With this change:
slabtop -o | head
Active / Total Objects (% used) : 869731 / 952904 (91.3%)
Active / Total Slabs (% used) : 103411 / 103974 (99.5%)
Active / Total Caches (% used) : 135 / 211 (64.0%)
Active / Total Size (% used) : 395389.68K / 411430.20K (96.1%)
Minimum / Average / Maximum Object : 0.02K / 0.43K / 8.00K
OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
244412 244239 99% 1.00K 61103 4 244412K iommu_iova_magazine
91636 88343 96% 0.03K 739 124 2956K kmalloc-32
75744 74844 98% 0.12K 2367 32 9468K kernfs_node_cache
On this machine it is now clear that magazine use 242M of kmem memory.
Those caches could do with a trimming ...
See the discussion on v1 for more details:
https://lore.kernel.org/linux-iommu/20240201193014.2785570-1-tatashin@xxxxxxxxxx/
but it seems this really is the idle baseline for lots of CPUs * lots of
domains - if all those devices get going in anger it's likely that
combined iova + iova_magazine usage truly will blow up into gigabytes.
Cheers,
Robin.
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
[ rm: adjust to rework of iova_cache_{get,put} ]
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
---
FWIW:
Reviewed-by: John Garry <john.g.garry@xxxxxxxxxx>
