Re: [PATCH net-next] rhashtable: Allow other tasks to be scheduled in large lookup loops

Eric Dumazet
2015-07-17T08:24:21Z

On Fri, 2015-07-17 at 10:07 +0200, Thomas Graf wrote:
> Depending on system speed, the large lookup loop can take a considerable
> amount of time to complete causing watchdog warnings to appear. Allow
> other tasks to be scheduled after every batch of 1000 lookups.
>
> Reported-by: Meelis Roos <mroos@linux.ee>
> Signed-off-by: Thomas Graf <tgraf@suug.ch>
> ---
> lib/test_rhashtable.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
> index c90777e..5ed6211 100644
> --- a/lib/test_rhashtable.c
> +++ b/lib/test_rhashtable.c
> @@ -20,8 +20,10 @@
> #include <linux/rcupdate.h>
> #include <linux/rhashtable.h>
> #include <linux/slab.h>
> +#include <linux/sched.h>
>
> #define MAX_ENTRIES 1000000
> +#define RELAX_CPU_AFTER 1000
> #define TEST_INSERT_FAIL INT_MAX
>
> static int entries = 50000;
> @@ -61,7 +63,7 @@ static struct rhashtable_params test_rht_params = {
>
> static int __init test_rht_lookup(struct rhashtable *ht)
> {
> - unsigned int i;
> + unsigned int i, relax_cnt = RELAX_CPU_AFTER;
>
> for (i = 0; i < entries * 2; i++) {
> struct test_obj *obj;
> @@ -87,6 +89,11 @@ static int __init test_rht_lookup(struct rhashtable *ht)
> return -EINVAL;
> }
> }
> +
> + if (!relax_cnt--) {
> + schedule();
> + relax_cnt = RELAX_CPU_AFTER;
> + }
> }
>
> return 0;

Please simply use cond_resched() without counting and magic value.