Re: [dpdk-dev] [PATCH] net/virtio-user: fix hugepage files enumeration

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 4/26/2018 4:34 PM, Jianfeng Tan wrote:
> After the commit 2a04139f66b4 ("eal: add single file segments option"),
> one hugepage file could contain multiple hugepages which are further
> mapped to different memory regions.
> 
> Original enumeration implementation cannot handle this situation.
> 
> This patch filters out the duplicated files; and adjust the size after
> the enumeration.
> 
> Fixes: 6a84c37e3975 ("net/virtio-user: add vhost-user adapter layer")
> 
> Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
> ---
>  .../howto/virtio_user_for_container_networking.rst |  3 ++-
>  drivers/net/virtio/virtio_user/vhost_user.c        | 28 ++++++++++++++++++++--
>  2 files changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/doc/guides/howto/virtio_user_for_container_networking.rst b/doc/guides/howto/virtio_user_for_container_networking.rst
> index aa68b53..476ce3a 100644
> --- a/doc/guides/howto/virtio_user_for_container_networking.rst
> +++ b/doc/guides/howto/virtio_user_for_container_networking.rst
> @@ -109,7 +109,8 @@ We have below limitations in this solution:
>   * Cannot work with --no-huge option. Currently, DPDK uses anonymous mapping
>     under this option which cannot be reopened to share with vhost backend.
>   * Cannot work when there are more than VHOST_MEMORY_MAX_NREGIONS(8) hugepages.
> -   In another word, do not use 2MB hugepage so far.
> +   If you have more regions (especially when 2MB hugepages are used), the option,
> +   --single-file-segments, can help to reduce the number of shared files.
>   * Applications should not use file name like HUGEFILE_FMT ("%smap_%d"). That
>     will bring confusion when sharing hugepage files with backend by name.
>   * Root privilege is a must. DPDK resolves physical addresses of hugepages
> diff --git a/drivers/net/virtio/virtio_user/vhost_user.c b/drivers/net/virtio/virtio_user/vhost_user.c
> index a6df97a..01201c9 100644
> --- a/drivers/net/virtio/virtio_user/vhost_user.c
> +++ b/drivers/net/virtio/virtio_user/vhost_user.c
> @@ -138,12 +138,13 @@ struct hugepage_file_info {
>  static int
>  get_hugepage_file_info(struct hugepage_file_info huges[], int max)
>  {
> -	int idx;
> +	int idx, k, exist;
>  	FILE *f;
>  	char buf[BUFSIZ], *tmp, *tail;
>  	char *str_underline, *str_start;
>  	int huge_index;
>  	uint64_t v_start, v_end;
> +	struct stat stats;
>  
>  	f = fopen("/proc/self/maps", "r");
>  	if (!f) {
> @@ -183,16 +184,39 @@ get_hugepage_file_info(struct hugepage_file_info huges[], int max)
>  		if (sscanf(str_start, "map_%d", &huge_index) != 1)
>  			continue;
>  
> +		/* skip duplicated file which is mapped to different regions */
> +		for (k = 0, exist = -1; k < idx; ++k) {
> +			if (!strcmp(huges[k].path, tmp)) {
> +				exist = k;
> +				break;
> +			}
> +		}
> +		if (exist >= 0)
> +			continue;
> +
>  		if (idx >= max) {
>  			PMD_DRV_LOG(ERR, "Exceed maximum of %d", max);
>  			goto error;
>  		}
> +
>  		huges[idx].addr = v_start;
> -		huges[idx].size = v_end - v_start;
> +		huges[idx].size = v_end - v_start; /* To be corrected later */
>  		snprintf(huges[idx].path, PATH_MAX, "%s", tmp);
>  		idx++;
>  	}
>  
> +	/* correct the size for files who have many regions */
> +	for (k = 0; k < idx; ++k) {
> +		if (stat(huges[k].path, &stats) < 0) {
> +			PMD_DRV_LOG(ERR, "Failed to stat %s, %s\n",
> +				    huges[k].path, strerror(errno));
> +			continue;
> +		}
> +		huges[k].size = stats.st_size;
> +		PMD_DRV_LOG(INFO, "file %s, size %"PRIx64"\n",
> +			    huges[k].path, huges[k].size);

This cause a build error for 32bits [1], %z should be used for size_t, will fix
while applying.

[1]
.../drivers/net/virtio/virtio_user/vhost_user.c(216): error #181: argument of
type "size_t={unsigned int}" is incompatible with format "%llx", expecting
argument of type "unsigned long long"
                PMD_DRV_LOG(INFO, "file %s, size %"PRIx64"\n",

                ^

> +	}
> +
>  	fclose(f);
>  	return idx;
>  
>