Re: [PATCH v2 02/26] selftests/resctrl: Split fill_buf to allow tests finer-grained control

Reinette Chatre
2023-11-28T22:10:30Z

Hi Ilpo,

On 11/20/2023 3:13 AM, Ilpo Järvinen wrote:
> MBM, MBA and CMT test cases call run_fill_buf() that in turn calls
> fill_cache() to alloc and loop indefinitely around the buffer. This
> binds buffer allocation and running the benchmark into a single bundle
> so that a selftest cannot allocate a buffer once and reuse it. CAT test
> doesn't want to loop around the buffer continuously and after rewrite
> it needs the ability to allocate the buffer separately.
>
> Split buffer allocation out of fill_cache() into alloc_buffer(). This
> change is part of preparation for the new CAT test that allocates a
> buffer and does multiple passes over the same buffer (but not in an
> infinite loop).
>
> Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> ---

Could you please list the changes to a patch in this area instead of
lumping all in the cover letter? Without this it is not clear what,
if anything, changed in the new version.

> tools/testing/selftests/resctrl/fill_buf.c | 26 +++++++++++++---------
> 1 file changed, 15 insertions(+), 11 deletions(-)
>
> diff --git a/tools/testing/selftests/resctrl/fill_buf.c b/tools/testing/selftests/resctrl/fill_buf.c
> index 0d425f26583a..6f32f44128e1 100644
> --- a/tools/testing/selftests/resctrl/fill_buf.c
> +++ b/tools/testing/selftests/resctrl/fill_buf.c
> @@ -135,33 +135,37 @@ static int fill_cache_write(unsigned char *buf, size_t buf_size, bool once)
> return 0;
> }
>
> -static int fill_cache(size_t buf_size, int memflush, int op, bool once)
> +static unsigned char *alloc_buffer(size_t buf_size, int memflush)
> {
> unsigned char *buf;
> - int ret;
>
> buf = malloc_and_init_memory(buf_size);
> if (!buf)
> - return -1;
> + return NULL;
>
> /* Flush the memory before using to avoid "cache hot pages" effect */
> if (memflush)
> mem_flush(buf, buf_size);
>
> + return buf;
> +}
> +
> +static int fill_cache(size_t buf_size, int memflush, int op, bool once)
> +{
> + unsigned char *buf;
> + int ret;
> +
> + buf = alloc_buffer(buf_size, memflush);
> + if (!buf)
> + return -1;
> +
> if (op == 0)
> ret = fill_cache_read(buf, buf_size, once);
> else
> ret = fill_cache_write(buf, buf_size, once);
> -
> free(buf);
>
> - if (ret) {
> - printf("\n Error in fill cache read/write...\n");
> - return -1;
> - }
> -

The changelog does not motivate the removal of this error message.
It seems ok at this point since the only failing functions already
print their own error message. Without a motivation of this change
it is not clear if it is actually intended.

In any case, this looks good.

Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>

Reinette