percpu: add a schedule point in pcpu_balance_workfn()

When a large BPF percpu map is destroyed, I have seen pcpu_balance_workfn() holding cpu for hundreds of milliseconds. On KASAN config and 112 hyperthreads, average time to destroy a chunk is ~4 ms. [ 2489.841376] destroy chunk 1 in 4148689 ns ... [ 2490.093428] destroy chunk 32 in 4072718 ns Signed-off-by: Eric Dumazet <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
sfionov · Feb 23, 2018 · accd4f3 · accd4f3
1 parent 554fef1
commit accd4f3
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/mm/percpu.c b/mm/percpu.c
@@ -1610,6 +1610,7 @@ static void pcpu_balance_workfn(struct work_struct *work)
 			spin_unlock_irq(&pcpu_lock);
 		}
 		pcpu_destroy_chunk(chunk);
+		cond_resched();
 	}
 
 	/*