Re: [LTP] [PATCH 12/13] Hugetlb: Migrating libhugetlbfs shm-fork

[Li Wang <liwang@redhat.com>]

On Sun, Dec 25, 2022 at 11:43 PM Tarun Sahu <tsahu@linux.ibm.com> wrote:

> Migrating the libhugetlbfs/testcases/shm-fork.c test
>
> Test Description: Test shared memory behavior when multiple threads are
> Test shared memory behavior when multiple threads are attached
> to a segment.  A segment is created and then children are
> spawned which attach, write, read (verify), and detach from the
> shared memory segment.
>
> Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
> ---
>  runtest/hugetlb                               |   1 +
>  testcases/kernel/mem/.gitignore               |   1 +
>  .../kernel/mem/hugetlb/hugefork/hugefork02.c  | 104 ++++++++++++++++++
>  3 files changed, 106 insertions(+)
>  create mode 100644 testcases/kernel/mem/hugetlb/hugefork/hugefork02.c
>
> diff --git a/runtest/hugetlb b/runtest/hugetlb
> index 33fd384b4..348a7dc5f 100644
> --- a/runtest/hugetlb
> +++ b/runtest/hugetlb
> @@ -2,6 +2,7 @@ hugefallocate01 hugefallocate01
>  hugefallocate02 hugefallocate02
>
>  hugefork01 hugefork01
> +hugefork02 hugefork02 -P 3 -s 5
>
>  hugemmap01 hugemmap01
>  hugemmap02 hugemmap02
> diff --git a/testcases/kernel/mem/.gitignore
> b/testcases/kernel/mem/.gitignore
> index 8375389cd..0c1311303 100644
> --- a/testcases/kernel/mem/.gitignore
> +++ b/testcases/kernel/mem/.gitignore
> @@ -2,6 +2,7 @@
>  /hugetlb/hugefallocate/hugefallocate01
>  /hugetlb/hugefallocate/hugefallocate02
>  /hugetlb/hugefork/hugefork01
> +/hugetlb/hugefork/hugefork02
>  /hugetlb/hugemmap/hugemmap01
>  /hugetlb/hugemmap/hugemmap02
>  /hugetlb/hugemmap/hugemmap04
> diff --git a/testcases/kernel/mem/hugetlb/hugefork/hugefork02.c
> b/testcases/kernel/mem/hugetlb/hugefork/hugefork02.c
> new file mode 100644
> index 000000000..6596bf81f
> --- /dev/null
> +++ b/testcases/kernel/mem/hugetlb/hugefork/hugefork02.c
> @@ -0,0 +1,104 @@
> +// SPDX-License-Identifier: LGPL-2.1-or-later
> +/*
> + * Copyright (C) 2005-2006 David Gibson & Adam Litke, IBM Corporation.
> + * Author: David Gibson & Adam Litke
> + */
> +
> +/*\
> + * [Description]
> + *
> + * Test shared memory behavior when multiple threads are attached to a
> + * segment. A segment is created and then children are spawned which
> + * attach, write, read (verify), and detach from the shared memory
> segment.
> + */
> +
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include <sys/mount.h>
> +#include <limits.h>
> +#include <sys/param.h>
> +#include <setjmp.h>
> +#include <sys/types.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/shm.h>
> +
> +#include "tst_safe_sysv_ipc.h"
> +#include "hugetlb.h"
> +
> +static int shmid = -1;
> +
> +#define NR_HUGEPAGES 5
>



> +#define NUMPROCS 20
>

Defining a fixed number to fork children might not be wise.

A sanity way is to detect the available NCPUS and create
corresponding children (or twice the amount), this will benefit
small machines (e.g. KVM guest with only single CPU).
For a system with a larger number of CPUs, just choose 20 as
the default will be OK.

LTP has tst_ncpus_available() function for getting available NCPUS.



> +#define MNTPOINT "hugetlbfs/"
>


> +#define MAX_PROCS 200
> +#define BUF_SZ 256
>

I don't see any places using these two macros.


+
> +static long hpage_size;
> +
> +static void do_child(int thread, unsigned long size)
> +{
> +       volatile char *shmaddr;
> +       int j;
> +       unsigned long k;
> +
> +       for (j = 0; j < 5; j++) {
> +               shmaddr = SAFE_SHMAT(shmid, 0, SHM_RND);
> +
> +               for (k = 0; k < size; k++)
> +                       shmaddr[k] = (char) (k);
> +               for (k = 0; k < size; k++)
> +                       if (shmaddr[k] != (char)k) {
> +                               tst_res(TFAIL, "Thread %d, Offset %lu
> mismatch", thread, k);
> +                               goto cleanup;
> +                       }
> +
> +               SAFE_SHMDT((const void *)shmaddr);
> +       }
> +cleanup:
> +       exit(0);
> +}
> +
> +static void run_test(void)
> +{
> +       unsigned long size;
> +       int pid;
> +       int i;
> +
> +       size = hpage_size * NR_HUGEPAGES;
> +       shmid = SAFE_SHMGET(2, size, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
> +
> +       for (i = 0; i < NUMPROCS; i++) {
> +               pid = SAFE_FORK();
> +
> +               if (pid == 0)
> +                       do_child(i, size);
> +       }
> +
> +       tst_reap_children();
> +       tst_res(TPASS, "Successfully tested shared hugetlb memory with
> multiple procs");
> +}
> +
> +static void setup(void)
> +{
> +       hpage_size = SAFE_READ_MEMINFO(MEMINFO_HPAGE_SIZE)*1024;
> +}
> +
> +static void cleanup(void)
> +{
> +       if (shmid >= 0)
> +               SAFE_SHMCTL(shmid, IPC_RMID, NULL);
> +}
> +
> +static struct tst_test test = {
> +       .needs_root = 1,
> +       .mntpoint = MNTPOINT,
> +       .needs_hugetlbfs = 1,
> +       .needs_tmpdir = 1,
> +       .forks_child = 1,
> +       .setup = setup,
> +       .cleanup = cleanup,
> +       .test_all = run_test,
> +       .hugepages = {NR_HUGEPAGES, TST_NEEDS},
> +};
> --
> 2.31.1
>
>

-- 
Regards,
Li Wang

-- 
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