[dpdk-dev] [RFC v2 10/23] eal: read hugepage counts from node-specific sysfs path

[Anatoly Burakov <anatoly.burakov@intel.com>]

For non-legacy memory init mode, instead of looking at generic
sysfs path, look at sysfs paths pertaining to each NUMA node
for hugepage counts. Note that per-NUMA node path does not
provide information regarding reserved pages, so we might not
get the best info from these paths, but this saves us from the
whole mapping/remapping business before we're actually able to
tell which page is on which socket, because we no longer require
our memory to be physically contiguous.

Legacy memory init will not use this.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/librte_eal/linuxapp/eal/eal_hugepage_info.c | 73 +++++++++++++++++++++++--
 1 file changed, 67 insertions(+), 6 deletions(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal_hugepage_info.c b/lib/librte_eal/linuxapp/eal/eal_hugepage_info.c
index 86e174f..a85c15a 100644
--- a/lib/librte_eal/linuxapp/eal/eal_hugepage_info.c
+++ b/lib/librte_eal/linuxapp/eal/eal_hugepage_info.c
@@ -59,6 +59,7 @@
 #include "eal_filesystem.h"
 
 static const char sys_dir_path[] = "/sys/kernel/mm/hugepages";
+static const char sys_pages_numa_dir_path[] = "/sys/devices/system/node";
 
 /* this function is only called from eal_hugepage_info_init which itself
  * is only called from a primary process */
@@ -99,6 +100,42 @@ get_num_hugepages(const char *subdir)
 	return num_pages;
 }
 
+static uint32_t
+get_num_hugepages_on_node(const char *subdir, unsigned socket) {
+	char path[PATH_MAX], socketpath[PATH_MAX];
+	DIR *socketdir;
+	long unsigned num_pages = 0;
+	const char *nr_hp_file = "free_hugepages";
+
+	snprintf(socketpath, sizeof(socketpath), "%s/node%u/hugepages",
+		 sys_pages_numa_dir_path, socket);
+
+	socketdir = opendir(socketpath);
+	if (socketdir) {
+		/* Keep calm and carry on */
+		closedir(socketdir);
+	} else {
+		/* Can't find socket dir, so ignore it */
+		return 0;
+	}
+
+	snprintf(path, sizeof(path), "%s/%s/%s",
+			socketpath, subdir, nr_hp_file);
+	if (eal_parse_sysfs_value(path, &num_pages) < 0)
+		return 0;
+
+	if (num_pages == 0)
+		RTE_LOG(WARNING, EAL, "No free hugepages reported in %s\n",
+				subdir);
+
+	/* we want to return a uint32_t and more than this looks suspicious
+	 * anyway ... */
+	if (num_pages > UINT32_MAX)
+		num_pages = UINT32_MAX;
+
+	return num_pages;
+}
+
 static uint64_t
 get_default_hp_size(void)
 {
@@ -277,7 +314,7 @@ eal_hugepage_info_init(void)
 {
 	const char dirent_start_text[] = "hugepages-";
 	const size_t dirent_start_len = sizeof(dirent_start_text) - 1;
-	unsigned i, num_sizes = 0;
+	unsigned i, total_pages, num_sizes = 0;
 	DIR *dir;
 	struct dirent *dirent;
 
@@ -331,9 +368,24 @@ eal_hugepage_info_init(void)
 		if (clear_hugedir(hpi->hugedir) == -1)
 			break;
 
-		/* for now, put all pages into socket 0,
-		 * later they will be sorted */
-		hpi->num_pages[0] = get_num_hugepages(dirent->d_name);
+		/* first, try to put all hugepages into relevant sockets, but
+		 * if first attempts fails, fall back to collecting all pages
+		 * in one socket and sorting them later */
+		total_pages = 0;
+		/* we also don't want to do this for legacy init */
+		if (!internal_config.legacy_mem)
+			for (i = 0; i < rte_num_sockets(); i++) {
+				unsigned num_pages =
+						get_num_hugepages_on_node(
+							dirent->d_name, i);
+				hpi->num_pages[i] = num_pages;
+				total_pages += num_pages;
+			}
+		/* we failed to sort memory from the get go, so fall
+		 * back to old way */
+		if (total_pages == 0) {
+			hpi->num_pages[0] = get_num_hugepages(dirent->d_name);
+		}
 
 #ifndef RTE_ARCH_64
 		/* for 32-bit systems, limit number of hugepages to
@@ -357,10 +409,19 @@ eal_hugepage_info_init(void)
 	      sizeof(internal_config.hugepage_info[0]), compare_hpi);
 
 	/* now we have all info, check we have at least one valid size */
-	for (i = 0; i < num_sizes; i++)
+	for (i = 0; i < num_sizes; i++) {
+		/* pages may no longer all be on socket 0, so check all */
+		unsigned j, num_pages = 0;
+
+		for (j = 0; j < RTE_MAX_NUMA_NODES; j++) {
+			struct hugepage_info *hpi =
+					&internal_config.hugepage_info[i];
+			num_pages += hpi->num_pages[j];
+		}
 		if (internal_config.hugepage_info[i].hugedir != NULL &&
-		    internal_config.hugepage_info[i].num_pages[0] > 0)
+				num_pages > 0)
 			return 0;
+	}
 
 	/* no valid hugepage mounts available, return error */
 	return -1;
-- 
2.7.4