[LTP] [RFC PATCH 1/2] lib: add support for kinds of hpsize reservation

[Li Wang]

Typically when we make use of huge page via LTP library, .hugepages choose
the default hugepage size, but this can not satisfy all scenarios.

So this patch introduces applying a specified hpsize huge page for user.

There is nothing that needs to change for the existing test cases which
already using .hugepages, it only needs to fill one more field in the
structure of .hugepages if a different hpsize is required.

e.g.

    static struct tst_test test = {
	.needs_root = 1,
	...
	.hugepages = {2, TST_NEEDS, 1048576},
    };

Signed-off-by: Li Wang <liwang@redhat.com>
---
 doc/c-test-api.txt     | 37 +++++++++++++++++++++++++++++++++++--
 include/tst_hugepage.h |  1 +
 lib/tst_hugepage.c     | 23 +++++++++++++++++------
 3 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/doc/c-test-api.txt b/doc/c-test-api.txt
index dcb6e1ba8..45610474c 100644
--- a/doc/c-test-api.txt
+++ b/doc/c-test-api.txt
@@ -2034,9 +2034,15 @@ For full documentation see the comments in 'include/tst_fuzzy_sync.h'.
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
 Many of the LTP tests need to use hugepage in their testing, this allows the
-test can reserve hugepages from system via '.hugepages = {xx, TST_REQUEST}'.
+test can reserve specify size of hugepages from system via:
+  '.hugepages = {xx, TST_REQUEST, yy}'.
 
-We achieved two policies for reserving hugepages:
+xx: This is used to set how many pages we wanted.
+
+yy: This is used to specify the size of the hugepage.
+    (If not set it will use the default hugepage size)
+
+Two policies for reserving hugepages:
 
 TST_REQUEST:
   It will try the best to reserve available huge pages and return the number
@@ -2103,6 +2109,33 @@ struct tst_test test = {
 };
 -------------------------------------------------------------------------------
 
+or,
+
+[source,c]
+-------------------------------------------------------------------------------
+#include "tst_test.h"
+
+static void run(void)
+{
+	...
+}
+
+static void setup(void)
+{
+	/*
+	 * Specify hpsize reserved automatically in the library
+	 * $ echo 2 > /sys/kernel/mm//hugepages/hugepages-1048576kB/nr_hugepages
+	 * Do check if 2 hpages are reserved correctly in there
+	 */
+}
+
+struct tst_test test = {
+	.test_all = run,
+	.hugepages = {2, TST_NEEDS, 1048576},
+	...
+};
+-------------------------------------------------------------------------------
+
 1.35 Checking for required commands
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/include/tst_hugepage.h b/include/tst_hugepage.h
index 46327c79a..e96bfbe53 100644
--- a/include/tst_hugepage.h
+++ b/include/tst_hugepage.h
@@ -27,6 +27,7 @@ enum tst_hp_policy {
 struct tst_hugepage {
 	const unsigned long number;
 	enum  tst_hp_policy policy;
+	const unsigned long hpsize;
 };
 
 /*
diff --git a/lib/tst_hugepage.c b/lib/tst_hugepage.c
index 728a8c3ec..b6706d412 100644
--- a/lib/tst_hugepage.c
+++ b/lib/tst_hugepage.c
@@ -5,6 +5,7 @@
 
 #define TST_NO_DEFAULT_MAIN
 
+#include <stdio.h>
 #include "tst_test.h"
 #include "tst_hugepage.h"
 
@@ -22,9 +23,10 @@ size_t tst_get_hugepage_size(void)
 
 unsigned long tst_reserve_hugepages(struct tst_hugepage *hp)
 {
-	unsigned long val, max_hpages;
+	unsigned long val, max_hpages, hpsize;
+	char hugepage_path[PATH_MAX];
 	struct tst_path_val pvl = {
-		.path = PATH_NR_HPAGES,
+		.path = hugepage_path,
 		.val = NULL,
 		.flags = TST_SR_SKIP_MISSING | TST_SR_TCONF_RO
 	};
@@ -41,6 +43,13 @@ unsigned long tst_reserve_hugepages(struct tst_hugepage *hp)
 	else
 		tst_hugepages = hp->number;
 
+	if (hp->hpsize)
+		hpsize = hp->hpsize;
+	else
+		hpsize = SAFE_READ_MEMINFO(MEMINFO_HPAGE_SIZE);
+
+	sprintf(hugepage_path, PATH_HUGEPAGES"/hugepages-%lukB/nr_hugepages", hpsize);
+
 	if (hp->number == TST_NO_HUGEPAGES) {
 		tst_hugepages = 0;
 		goto set_hugepages;
@@ -52,7 +61,7 @@ unsigned long tst_reserve_hugepages(struct tst_hugepage *hp)
 		goto set_hugepages;
 	}
 
-	max_hpages = SAFE_READ_MEMINFO("MemFree:") / SAFE_READ_MEMINFO("Hugepagesize:");
+	max_hpages = SAFE_READ_MEMINFO("MemFree:") / hpsize;
 	if (tst_hugepages > max_hpages) {
 		tst_res(TINFO, "Requested number(%lu) of hugepages is too large, "
 				"limiting to 80%% of the max hugepage count %lu",
@@ -65,14 +74,16 @@ unsigned long tst_reserve_hugepages(struct tst_hugepage *hp)
 
 set_hugepages:
 	tst_sys_conf_save(&pvl);
-	SAFE_FILE_PRINTF(PATH_NR_HPAGES, "%lu", tst_hugepages);
-	SAFE_FILE_SCANF(PATH_NR_HPAGES, "%lu", &val);
+
+	SAFE_FILE_PRINTF(hugepage_path, "%lu", tst_hugepages);
+	SAFE_FILE_SCANF(hugepage_path, "%lu", &val);
+
 	if (val != tst_hugepages)
 		tst_brk(TCONF, "nr_hugepages = %lu, but expect %lu. "
 				"Not enough hugepages for testing.",
 				val, tst_hugepages);
 
-	if (hp->policy == TST_NEEDS) {
+	if ((hp->policy == TST_NEEDS) && (!hp->hpsize)) {
 		unsigned long free_hpages = SAFE_READ_MEMINFO("HugePages_Free:");
 		if (hp->number > free_hpages)
 			tst_brk(TCONF, "free_hpages = %lu, but expect %lu. "
-- 
2.40.0