[LTP] [PATCH] move_pages12: compacting memory before each test loop

[Petr Vorel]

Hi Li,

> These simple steps are added to prepare the system's memory state
> for the test, aiming to increase the test's reliability and
> consistency by starting from a clean and defragmented memory state.

> To reduce accidental failures on small (1.5G) RAM system:

>   7 tst_test.c:1558: TINFO: Timeout per run is 0h 21m 00s
>   8 move_pages12.c:273: TINFO: Free RAM 1542656 kB
>   9 move_pages12.c:289: TINFO: Increasing 16384kB hugepages pool on node 0 to 4
>   10 move_pages12.c:299: TINFO: Increasing 16384kB hugepages pool on node 1 to 4
>   11 move_pages12.c:216: TINFO: Allocating and freeing 4 hugepages on node 0
>   12 move_pages12.c:216: TINFO: Allocating and freeing 4 hugepages on node 1
>   13 move_pages12.c:207: TPASS: Bug not reproduced
>   14 move_pages12.c:106: TFAIL: madvise failed: ENOMEM (12)
>   ...<repeats 741 times>...
>   756 move_pages12.c:207: TPASS: Bug not reproduced

> Note:
>   This is a single hugetlb test without invoking the hugetlb-lib of LTP,
>   so we add the compacting memory/cache steps additionally.

> Signed-off-by: Li Wang <liwang@redhat.com>
> ---
>  testcases/kernel/syscalls/move_pages/move_pages12.c | 3 +++
>  1 file changed, 3 insertions(+)

> diff --git a/testcases/kernel/syscalls/move_pages/move_pages12.c b/testcases/kernel/syscalls/move_pages/move_pages12.c
> index fd7017d79..c387a326f 100644
> --- a/testcases/kernel/syscalls/move_pages/move_pages12.c
> +++ b/testcases/kernel/syscalls/move_pages/move_pages12.c
> @@ -154,6 +154,9 @@ static void do_test(unsigned int n)
>  	pid_t cpid = -1;
>  	int status;

> +	SAFE_FILE_PRINTF("/proc/sys/vm/drop_caches", "3");
> +	SAFE_FILE_PRINTF("/proc/sys/vm/compact_memory", "1");

LGTM
Reviewed-by: Petr Vorel <pvorel@suse.cz>

BTW we clear cache with /proc/sys/vm/drop_caches in quite a few files,
I wonder if it would make sense to add a helper for it. Likely not
(it's oneliner).

Kind regards,
Petr

> +
>  	addr = SAFE_MMAP(NULL, tcases[n].tpages * hpsz, PROT_READ | PROT_WRITE,
>  		MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);