mem: count overcommit hugepages as available

With nr_overcommit_hugepages > 0 application may be able to allocate
hugepages even when free_hugepages == 0. Take this into account when
counting available hugepages.

Signed-off-by: Michał Mirosław <michal.miroslaw@atendesoftware.pl>
Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>

diff --git a/lib/librte_eal/linux/eal/eal_hugepage_info.c b/lib/librte_eal/linux/eal/eal_hugepage_info.c
index 0eab1cf..ce3e992 100644 (file)
--- a/lib/librte_eal/linux/eal/eal_hugepage_info.c
+++ b/lib/librte_eal/linux/eal/eal_hugepage_info.c
@@ -70,30 +70,38 @@ create_shared_memory(const char *filename, const size_t mem_size)
        return map_shared_memory(filename, mem_size, O_RDWR | O_CREAT);
 }
 
+static int get_hp_sysfs_value(const char *subdir, const char *file, unsigned long *val)
+{
+       char path[PATH_MAX];
+
+       snprintf(path, sizeof(path), "%s/%s/%s",
+                       sys_dir_path, subdir, file);
+       return eal_parse_sysfs_value(path, val);
+}
+
 /* this function is only called from eal_hugepage_info_init which itself
  * is only called from a primary process */
 static uint32_t
 get_num_hugepages(const char *subdir)
 {
-       char path[PATH_MAX];
-       long unsigned resv_pages, num_pages = 0;
+       unsigned long resv_pages, num_pages, over_pages, surplus_pages;
        const char *nr_hp_file = "free_hugepages";
        const char *nr_rsvd_file = "resv_hugepages";
+       const char *nr_over_file = "nr_overcommit_hugepages";
+       const char *nr_splus_file = "surplus_hugepages";
 
        /* first, check how many reserved pages kernel reports */
-       snprintf(path, sizeof(path), "%s/%s/%s",
-                       sys_dir_path, subdir, nr_rsvd_file);
-       if (eal_parse_sysfs_value(path, &resv_pages) < 0)
+       if (get_hp_sysfs_value(subdir, nr_rsvd_file, &resv_pages) < 0)
                return 0;
 
-       snprintf(path, sizeof(path), "%s/%s/%s",
-                       sys_dir_path, subdir, nr_hp_file);
-       if (eal_parse_sysfs_value(path, &num_pages) < 0)
+       if (get_hp_sysfs_value(subdir, nr_hp_file, &num_pages) < 0)
                return 0;
 
-       if (num_pages == 0)
-               RTE_LOG(WARNING, EAL, "No free hugepages reported in %s\n",
-                               subdir);
+       if (get_hp_sysfs_value(subdir, nr_over_file, &over_pages) < 0)
+               over_pages = 0;
+
+       if (get_hp_sysfs_value(subdir, nr_splus_file, &surplus_pages) < 0)
+               surplus_pages = 0;
 
        /* adjust num_pages */
        if (num_pages >= resv_pages)
@@ -101,6 +109,19 @@ get_num_hugepages(const char *subdir)
        else if (resv_pages)
                num_pages = 0;
 
+       if (over_pages >= surplus_pages)
+               over_pages -= surplus_pages;
+       else
+               over_pages = 0;
+
+       if (num_pages == 0 && over_pages == 0)
+               RTE_LOG(WARNING, EAL, "No available hugepages reported in %s\n",
+                               subdir);
+
+       num_pages += over_pages;
+       if (num_pages < over_pages) /* overflow */
+               num_pages = UINT32_MAX;
+
        /* we want to return a uint32_t and more than this looks suspicious
         * anyway ... */
        if (num_pages > UINT32_MAX)