Re: [PATCH v3 3/3] iommu/iova: use named kmem_cache for iova magazines

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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>




[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux