[LTP] [PATCH 09/29] Hugetlb: Migrating libhugetlbfs fork-cow

[Li Wang]

Tarun Sahu <tsahu@linux.ibm.com> wrote:



> +static void run_test(void)
> +{
> +       int status;
> +       void *syncarea;
> +       volatile unsigned int *p;
> +       volatile unsigned int *trigger, *child_readback;
> +       int parent_readback;
> +       pid_t pid;
> +       struct sigaction sa = {
> +               .sa_sigaction = sigchld_handler,
> +               .sa_flags = SA_SIGINFO,
> +       };
> +
> +       /* Get a shared normal page for synchronization */
> +       if (verbose)
> +               tst_res(TINFO, "Mapping synchronization area..");
> +       syncarea = SAFE_MMAP(NULL, getpagesize(), PROT_READ|PROT_WRITE,
> +                       MAP_SHARED|MAP_ANONYMOUS, -1, 0);
> +       if (verbose)
> +               tst_res(TINFO, "done");
> +
> +       trigger = syncarea;
> +       *trigger = 0;
> +
> +       child_readback = trigger + 1;
> +       *child_readback = 0;
> +
> +       fd = SAFE_OPEN(hfile, O_RDWR | O_CREAT, 0600);
> +       SAFE_UNLINK(hfile);
> +
> +       if (verbose)
> +               tst_res(TINFO, "Mapping hugepage area...");
> +       p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
> fd, 0);
>


After roughly looking at those hpage testcases, almost each one
requests the huge memory via mapping a file on hugetlbfs, which
can work but quite don't have to.

We can absolutely simplify them via `MAP_HUGETLB` to get expected
size of huge memory for use.

Reference how hugemamp06.c does:
https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c#L71


+static void setup(void)
> +{
> +       int free_pages = SAFE_READ_MEMINFO("HugePages_Free:");
> +
> +       if (tst_hugepages < 2 || free_pages < 2)
> +               tst_brk(TCONF, "Not enough hugepages for testing.");
>



> +
> +       if (!Hopt)
> +               Hopt = tst_get_tmpdir();
> +       SAFE_MOUNT("none", Hopt, "hugetlbfs", 0, NULL);
> +
> +       snprintf(hfile, sizeof(hfile), "%s/ltp_hugetlbfile%d", Hopt,
> getpid());
>

If we go using MAP_HUGETLB above, those lines can be removed.



> +       hpage_size = SAFE_READ_MEMINFO("Hugepagesize:")*1024;
> +}
>



-- 
Regards,
Li Wang
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