iommu/iova: Separate atomic variables to improve performance (14bd9a60) · Commits · 戴 / test

In struct iova_domain, there are three atomic variables, the former two are about TLB flush counters which use atomic_add operation, anoter is used to flush timer that use cmpxhg operation. These variables are in the same cache line, so it will cause some performance loss under the condition that many cores call queue_iova function, Let's isolate the two type atomic variables to different cache line to reduce cache line conflict. Cc: Joerg Roedel <joro@8bytes.org> Signed-off-by:

Jinyu Qi <jinyuqi@huawei.com> Signed-off-by:

Joerg Roedel <jroedel@suse.de>

include/linux/iova.h

+8 −8

Original line number	Diff line number	Diff line
		@@ -76,6 +76,14 @@ struct iova_domain {
		unsigned long start_pfn; /* Lower limit for this domain */
		unsigned long dma_32bit_pfn;
		unsigned long max32_alloc_size; /* Size of last failed allocation */
		struct iova_fq __percpu fq; / Flush Queue */

		atomic64_t fq_flush_start_cnt; /* Number of TLB flushes that
		have been started */

		atomic64_t fq_flush_finish_cnt; /* Number of TLB flushes that
		have been finished */

		struct iova anchor; /* rbtree lookup anchor */
		struct iova_rcache rcaches[IOVA_RANGE_CACHE_MAX_SIZE]; /* IOVA range caches */

		@@ -85,14 +93,6 @@ struct iova_domain {
		iova_entry_dtor entry_dtor; /* IOMMU driver specific destructor for
		iova entry */

		struct iova_fq __percpu fq; / Flush Queue */

		atomic64_t fq_flush_start_cnt; /* Number of TLB flushes that
		have been started */

		atomic64_t fq_flush_finish_cnt; /* Number of TLB flushes that
		have been finished */

		struct timer_list fq_timer; /* Timer to regularily empty the
		flush-queues */
		atomic_t fq_timer_on; /* 1 when timer is active, 0

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