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RDMA/core: Reduce cond_resched() frequency in __ib_umem_release

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The current implementation calls cond_resched() for every SG entry
in __ib_umem_release(), which can increase needless overhead.

This patch introduces RESCHED_LOOP_CNT_THRESHOLD (0x1000) to limit
how often cond_resched() is called. The function now yields the CPU
once every 4096 iterations, and yield at the very first iteration
for lots of small umem case, to reduce scheduling overhead.

Fixes: d056bc45b6 ("RDMA/core: Prevent soft lockup during large user memory region cleanup")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Link: https://patch.msgid.link/20251126025147.2627-1-lirongqing@baidu.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
This commit is contained in:
Li RongQing
2025-11-26 10:51:47 +08:00
committed by Leon Romanovsky
parent 01dad9ca37
commit f37e286879
1 changed files with 5 additions and 1 deletions
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6
drivers/infiniband/core/umem.c
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@@ -45,6 +45,8 @@
#include "uverbs.h"
#define RESCHED_LOOP_CNT_THRESHOLD 0x1000
static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
bool make_dirty = umem->writable && dirty;
@@ -58,7 +60,9 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
for_each_sgtable_sg(&umem->sgt_append.sgt, sg, i) {
unpin_user_page_range_dirty_lock(sg_page(sg),
DIV_ROUND_UP(sg->length, PAGE_SIZE), make_dirty);
cond_resched();
if (i && !(i % RESCHED_LOOP_CNT_THRESHOLD))
cond_resched();
}
sg_free_append_table(&umem->sgt_append);