[dpdk-dev] [PATCH v2] mem: calculate space left in a hugetlbfs

[Jianfeng Tan <jianfeng.tan@intel.com>]

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.

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;
+}
+
+/* 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
-- 
2.1.4