Re: [PATCH v2] selftests/mm: use global variable to not optimize mmap read variable

On 6 Jun 2024, at 8:44, Pankaj Raghav (Samsung) wrote:

From: Pankaj Raghav p.raghav@samsung.com

create_pagecache_thp_and_fd() in split_huge_page_test.c used the variable dummy to perform mmap read.

However, this test was skipped even on XFS which has large folio support. The issue was compiler (gcc 13.2.0) was optimizing out the dummy variable, therefore, not creating huge page in the page cache.

Make it as a global variable to force the compiler not to optimize out the loop where we read from the mmaped addr.

Signed-off-by: Pankaj Raghav p.raghav@samsung.com

Changes since v1:

• Make the dummy variable as a global variable(willy).

tools/testing/selftests/mm/split_huge_page_test.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

Reviewed-by: Zi Yan ziy@nvidia.com

Thanks.

Best Regards, Yan, Zi