Commit 64361811 authored Jun 04, 2024 by Zhang Zekun

iommu/iova: move depot up to avoid cache conflict

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9TIC6



------------------------------------------

The first four params in struct iova_rcache will share the same
cache line. The depot related parameter which will be upated each
time the depot has been changed, and it should not influence the
field "cpu_rcache". Moving the delayed_work up to avoid cache
false-sharing, because it has 192 Bytes, which should be enough for
sperating a cache line. The optimization can be reflected by perf top:

Before:
  31.13%  [kernel]   [k] queue_iova
  23.02%  [kernel]   [k] __iova_rcache_get
   7.78%  [kernel]   [k] __arm_lpae_unmap
   6.18%  [kernel]   [k] arm_lpae_map
   3.91%  [kernel]   [k] sch_direct_xmit
   3.19%  [kernel]   [k] __arm_lpae_map
   1.50%  [kernel]   [k] __dev_queue_xmit

After:
  15.88%  [kernel]   [k] __arm_lpae_unmap
  11.33%  [kernel]   [k] arm_lpae_map
   7.98%  [kernel]   [k] sch_direct_xmit
   6.71%  [kernel]   [k] __arm_lpae_map
   5.35%  [kernel]   [k] queue_iova
   3.09%  [kernel]   [k] __dev_queue_xmit
   2.83%  [kernel]   [k] ip_finish_output2

Fixes: 876b598e ("iommu/iova: Make the rcache depot scale better")
Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com>

parent 83e8197d

include/linux/iova.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -31,9 +31,9 @@ struct iova_rcache {
		spinlock_t lock;
		unsigned int depot_size;
		struct iova_magazine *depot;
		struct delayed_work work;
		struct iova_cpu_rcache __percpu *cpu_rcaches;
		struct iova_domain *iovad;
		struct delayed_work work;
		KABI_RESERVE(1)
		KABI_RESERVE(2)
		};