Re: [PATCH v2] mem: calculate space left in a hugetlbfs

[Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>]

Hi,

On 12/11/2015 02:10, Jianfeng Tan wrote:
> This patch enables calculating space left in a hugetlbfs.
> There are three sources to get the information: 1. from
> sysfs; 2. from option size specified when mount; 3. use
> statfs. We should use the minimum one of these three sizes.
We could improve the message by stating the current issue (when the
hugetlbfs mount specifies size= option), then how the patch deals
with the problem and also outstanding issues.
> Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
> ---
> Changes in v2:
>   - reword title
>   - fix compiler error of v1
>
>   lib/librte_eal/linuxapp/eal/eal_hugepage_info.c | 85 ++++++++++++++++++++++++-
>   1 file changed, 84 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_eal/linuxapp/eal/eal_hugepage_info.c b/lib/librte_eal/linuxapp/eal/eal_hugepage_info.c
> index 18858e2..8305a58 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_hugepage_info.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_hugepage_info.c
> @@ -44,6 +44,8 @@
>   #include <unistd.h>
>   #include <errno.h>
>   #include <sys/queue.h>
> +#include <sys/vfs.h>
> +#include <mntent.h>
>   
>   #include <rte_memory.h>
>   #include <rte_memzone.h>
> @@ -189,6 +191,70 @@ get_hugepage_dir(uint64_t hugepage_sz)
>   	return retval;
>   }
>   
> +/* Caller to make sure this mnt_dir exist
> + */
> +static uint64_t
> +get_hugetlbfs_mount_size(const char *mnt_dir)
> +{
> +	char *start, *end, *opt_size;
> +	struct mntent *ent;
> +	uint64_t size;
> +	FILE *f;
> +	int len;
> +
> +	f = setmntent("/proc/mounts", "r");
> +	if (f == NULL) {
> +		RTE_LOG(ERR, EAL, "setmntent() error: %s\n",
> +			strerror(errno));
> +		return 0;
> +	}
> +	while (NULL != (ent = getmntent(f))) {
> +		if (!strcmp(ent->mnt_dir, mnt_dir))
> +			break;
> +	}
> +
> +	start = hasmntopt(ent, "size");
> +	if (start == NULL) {
> +		RTE_LOG(DEBUG, EAL, "option size not specified for %s\n",
> +			mnt_dir);
> +		size = 0;
> +		goto end;
> +	}
> +	start += strlen("size=");
> +	end = strstr(start, ",");
> +	if (end != NULL)
> +		len = end - start;
> +	else
> +		len = strlen(start);
> +	opt_size = strndup(start, len);
> +	size = rte_str_to_size(opt_size);
> +	free(opt_size);
> +
> +end:
> +	endmntent(f);
> +	return size;
> +}
> +
The function above is very similar to get_hugepage_dir, ie. open and parse
/proc/mounts.
I think it would be better to have a more generic function that retrieves
all needed info from /proc/mounts.
> +/* Caller to make sure this mount has option size
> + * so that statfs is not zero.
> + */
> +static uint64_t
> +get_hugetlbfs_free_size(const char *mnt_dir)
> +{
> +	int r;
> +	struct statfs stats;
> +
> +	r = statfs(mnt_dir, &stats);
> +	if (r != 0) {
> +		RTE_LOG(ERR, EAL, "statfs() error: %s\n",
> +			strerror(errno));
> +		return 0;
> +	}
> +
> +	return stats.f_bfree * stats.f_bsize;
> +}
> +
> +
>   /*
>    * Clear the hugepage directory of whatever hugepage files
>    * there are. Checks if the file is locked (i.e.
> @@ -329,9 +395,26 @@ eal_hugepage_info_init(void)
>   		if (clear_hugedir(hpi->hugedir) == -1)
>   			break;
>   
> +		/* there are three souces of how much space left in a
> +		 * hugetlbfs dir.
> +		 */
> +		uint64_t sz_left, sz_sysfs, sz_option, sz_statfs;
> +
> +		sz_sysfs = get_num_hugepages(dirent->d_name) *
> +			hpi->hugepage_sz;
> +		sz_left = sz_sysfs;
> +		sz_option = get_hugetlbfs_mount_size(hpi->hugedir);
> +		if (sz_option) {
> +			sz_statfs = get_hugetlbfs_free_size(hpi->hugedir);
> +			sz_left = RTE_MIN(sz_sysfs, sz_statfs);
> +			RTE_LOG(INFO, EAL, "sz_sysfs: %"PRIu64", sz_option: "
> +					"%"PRIu64", sz_statfs: %"PRIu64"\n",
> +					sz_sysfs, sz_option, sz_statfs);
> +		}
> +
>   		/* for now, put all pages into socket 0,
>   		 * later they will be sorted */
> -		hpi->num_pages[0] = get_num_hugepages(dirent->d_name);
> +		hpi->num_pages[0] = sz_left / hpi->hugepage_sz;
>   
>   #ifndef RTE_ARCH_64
>   		/* for 32-bit systems, limit number of hugepages to

A couple more things:
- Update release-notes and/or relevant doc about improved detection of 
free hugepages
- Update the status of previous/old patches in patchwork

Sergio