diff mbox series

[v4,1/2] lib: add .request_hugepages to reserve hugepage

Message ID 20200208092014.24824-1-liwang@redhat.com
State Accepted
Headers show
Series [v4,1/2] lib: add .request_hugepages to reserve hugepage | expand

Commit Message

Li Wang Feb. 8, 2020, 9:20 a.m. UTC 
Many of the ltp tests need to use hugepage in their testing, this allows
the test can reserve hpages from system only via .request_hugepages = xx.

If set non-zero number of request_hugepages, test will try to reserve the
expected number of hugepage for testing in setup phase. If system does not
have enough hpage for using, it will try the best to reserve 80% available
number of hpages. For a system without hugetlb supporting, variable
'tst_hugepage' will be set to 0.

Signed-off-by: Li Wang <liwang@redhat.com>
---

Notes:
    v3 --> v4
      * add doc to check the hpage number in setup()
      * remove the TCONF print if hugepage is not supported
      * check here that max_hpages * 0.8 > 1

 doc/test-writing-guidelines.txt | 58 ++++++++++++++++++++++++++++++++
 include/tst_hugepage.h          | 29 ++++++++++++++++
 include/tst_test.h              | 13 ++++++++
 lib/newlib_tests/.gitignore     |  1 +
 lib/newlib_tests/test20.c       | 45 +++++++++++++++++++++++++
 lib/tst_hugepage.c              | 59 +++++++++++++++++++++++++++++++++
 lib/tst_test.c                  |  6 ++--
 7 files changed, 209 insertions(+), 2 deletions(-)
 create mode 100644 include/tst_hugepage.h
 create mode 100644 lib/newlib_tests/test20.c
 create mode 100644 lib/tst_hugepage.c

Comments

Petr Vorel Feb. 17, 2020, 4:08 p.m. UTC | #1 
Hi Li,

Reviewed-by: Petr Vorel <pvorel@suse.cz>
Code looks good.
Minor issue: doc has broken formatting.

> +2.2.34 Reserving hugepages
> +^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Many of the ltp tests need to use hugepage in their testing, this allows the
> +test can reserve hugepages from system only via .request_hugepages = xx.
> +
> +If set non-zero number of request_hugepages, test will try to reserve the
> +expected number of hugepage for testing in setup phase. If system does not
> +have enough hpage for using, it will try the best to reserve 80% available
> +number of hpages. With success test stores the reserved hugepage number in
> +'tst_hugepages. For the system without hugetlb supporting, variable
Missing ' here   ^

> +'tst_hugepages' will be set to 0.

I propose these changes (+ strip this formatting from comments in C source - include/tst_test.h).

Kind regards,
Petr

diff --git doc/test-writing-guidelines.txt doc/test-writing-guidelines.txt
index b9f8d5ab0..ae9a8b040 100644
--- doc/test-writing-guidelines.txt
+++ doc/test-writing-guidelines.txt
@@ -1945,14 +1945,14 @@ For full documentation see the comments in 'include/tst_fuzzy_sync.h'.
 2.2.34 Reserving hugepages
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Many of the ltp tests need to use hugepage in their testing, this allows the
-test can reserve hugepages from system only via .request_hugepages = xx.
+Many of the LTP tests need to use hugepage in their testing, this allows the
+test can reserve hugepages from system only via '.request_hugepages = xx'.
 
-If set non-zero number of request_hugepages, test will try to reserve the
+If set non-zero number of 'request_hugepages', test will try to reserve the
 expected number of hugepage for testing in setup phase. If system does not
 have enough hpage for using, it will try the best to reserve 80% available
 number of hpages. With success test stores the reserved hugepage number in
-'tst_hugepages. For the system without hugetlb supporting, variable
+'tst_hugepages'. For the system without hugetlb supporting, variable
 'tst_hugepages' will be set to 0.
 
 Also, we do cleanup and restore work for the hpages resetting automatically.
@@ -1977,9 +1977,12 @@ struct tst_test test = {
 	.request_hugepages = 2,
 	...
 };
+[source,c]
+-------------------------------------------------------------------------------
 
 or,
 
+-------------------------------------------------------------------------------
 #include "tst_test.h"
 
 static void run(void)
Li Wang Feb. 18, 2020, 6:06 a.m. UTC | #2 
Hi Petr,

On Tue, Feb 18, 2020 at 12:08 AM Petr Vorel <pvorel@suse.cz> wrote:

> Hi Li,
>
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
> Code looks good.
>
Thanks!


> Minor issue: doc has broken formatting.
> ...
> > +'tst_hugepages' will be set to 0.
>
> I propose these changes (+ strip this formatting from comments in C source
> - include/tst_test.h).
>

Thanks for this advice, I have done modifications in my local commit.

Before pushing I would give a bit more time to Cyril for a review, in case
he has additional suggestions.
Cyril Hrubis Feb. 18, 2020, 4:27 p.m. UTC | #3 
Hi!
> Many of the ltp tests need to use hugepage in their testing, this allows
> the test can reserve hpages from system only via .request_hugepages = xx.
> 
> If set non-zero number of request_hugepages, test will try to reserve the
> expected number of hugepage for testing in setup phase. If system does not
> have enough hpage for using, it will try the best to reserve 80% available
> number of hpages. For a system without hugetlb supporting, variable
> 'tst_hugepage' will be set to 0.
> 
> Signed-off-by: Li Wang <liwang@redhat.com>
> ---
> 
> Notes:
>     v3 --> v4
>       * add doc to check the hpage number in setup()
>       * remove the TCONF print if hugepage is not supported
>       * check here that max_hpages * 0.8 > 1
> 
>  doc/test-writing-guidelines.txt | 58 ++++++++++++++++++++++++++++++++
>  include/tst_hugepage.h          | 29 ++++++++++++++++
>  include/tst_test.h              | 13 ++++++++
>  lib/newlib_tests/.gitignore     |  1 +
>  lib/newlib_tests/test20.c       | 45 +++++++++++++++++++++++++
>  lib/tst_hugepage.c              | 59 +++++++++++++++++++++++++++++++++
>  lib/tst_test.c                  |  6 ++--
>  7 files changed, 209 insertions(+), 2 deletions(-)
>  create mode 100644 include/tst_hugepage.h
>  create mode 100644 lib/newlib_tests/test20.c
>  create mode 100644 lib/tst_hugepage.c
> 
> diff --git a/doc/test-writing-guidelines.txt b/doc/test-writing-guidelines.txt
> index 546bb7a49..fa7cb89c1 100644
> --- a/doc/test-writing-guidelines.txt
> +++ b/doc/test-writing-guidelines.txt
> @@ -1933,6 +1933,64 @@ specified by the user plus some other heuristics.
>  
>  For full documentation see the comments in 'include/tst_fuzzy_sync.h'.
>  
> +2.2.34 Reserving hugepages
> +^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Many of the ltp tests need to use hugepage in their testing, this allows the
> +test can reserve hugepages from system only via .request_hugepages = xx.
> +
> +If set non-zero number of request_hugepages, test will try to reserve the
> +expected number of hugepage for testing in setup phase. If system does not
> +have enough hpage for using, it will try the best to reserve 80% available
> +number of hpages. With success test stores the reserved hugepage number in
> +'tst_hugepages. For the system without hugetlb supporting, variable
> +'tst_hugepages' will be set to 0.
> +
> +Also, we do cleanup and restore work for the hpages resetting automatically.
> +
> +[source,c]
> +-------------------------------------------------------------------------------
> +#include "tst_test.h"
> +
> +static void run(void)
> +{
> +	...
> +
> +	if (tst_hugepages == test.request_hugepages)
> +		TEST(do_hpage_test);
> +	else
> +		...
> +	...
> +}
> +
> +struct tst_test test = {
> +	.test_all = run,
> +	.request_hugepages = 2,
> +	...
> +};
> +
> +or,
> +
> +#include "tst_test.h"
> +
> +static void run(void)
> +{
> +	...
> +}
> +
> +static void setup(void)
> +{
> +        if (tst_hugepages != test.requested_hugepages)
> +                tst_brk(TCONF, "...");
> +}
> +
> +struct tst_test test = {
> +	.test_all = run,
> +	.request_hugepages = 2,
> +	...
> +};
> +-------------------------------------------------------------------------------
> +
>  2.3 Writing a testcase in shell
>  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>  
> diff --git a/include/tst_hugepage.h b/include/tst_hugepage.h
> new file mode 100644
> index 000000000..10e0eaf47
> --- /dev/null
> +++ b/include/tst_hugepage.h
> @@ -0,0 +1,29 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2019 Red Hat, Inc.
> + */
> +
> +#ifndef TST_HUGEPAGE__
> +#define TST_HUGEPAGE__
> +
> +#define PATH_HUGEPAGES	"/sys/kernel/mm/hugepages/"
> +#define PATH_NR_HPAGES	"/proc/sys/vm/nr_hugepages"
> +
> +/*
> + * Try the best to request a specified number of huge pages from system,
> + * it will store the reserved hpage number in tst_hugepages.
> + *
> + * Note: this depend on the status of system memory fragmentation.
> + */
> +int tst_request_hugepages(int hpages);
> +
> +/*
> + * This variable is used for recording the number of hugepages which system can
> + * provides. It will be equal to 'hpages' if tst_request_hugepages on success,
> + * otherwise set it to a number of hugepages that we were able to reserve.
> + *
> + * If system does not support hugetlb, then it will be set to 0.
> + */
> +extern unsigned int tst_hugepages;
> +
> +#endif /* TST_HUGEPAGE_H */
> diff --git a/include/tst_test.h b/include/tst_test.h
> index 21c7dfbdb..1026a422a 100644
> --- a/include/tst_test.h
> +++ b/include/tst_test.h
> @@ -37,6 +37,7 @@
>  #include "tst_coredump.h"
>  #include "tst_buffers.h"
>  #include "tst_capability.h"
> +#include "tst_hugepage.h"
>  
>  /*
>   * Reports testcase result.
> @@ -148,6 +149,18 @@ struct tst_test {
>  	 */
>  	int all_filesystems:1;
>  
> +	/*
> +	 * If set non-zero number of request_hugepages, test will try to reserve the
> +	 * expected number of hugepage for testing in setup phase. If system does not
> +	 * have enough hpage for using, it will try the best to reserve 80% available
> +	 * number of hpages. With success test stores the reserved hugepage number in
> +	 * 'tst_hugepages. For the system without hugetlb supporting, variable
> +	 * 'tst_hugepages' will be set to 0.
> +	 *
> +	 * Also, we do cleanup and restore work for the hpages resetting automatically.
> +	 */
> +	unsigned int request_hugepages;
> +
>  	/*
>  	 * If set non-zero denotes number of test variant, the test is executed
>  	 * variants times each time with tst_variant set to different number.
> diff --git a/lib/newlib_tests/.gitignore b/lib/newlib_tests/.gitignore
> index d4aa4935f..ab3a92c4c 100644
> --- a/lib/newlib_tests/.gitignore
> +++ b/lib/newlib_tests/.gitignore
> @@ -23,6 +23,7 @@ tst_strstatus
>  test17
>  test18
>  test19
> +test20
>  tst_expiration_timer
>  test_exec
>  test_exec_child
> diff --git a/lib/newlib_tests/test20.c b/lib/newlib_tests/test20.c
> new file mode 100644
> index 000000000..92e230976
> --- /dev/null
> +++ b/lib/newlib_tests/test20.c
> @@ -0,0 +1,45 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2019 Li Wang <liwang@redhat.com>
> + */
> +
> +/*
> + * Tests .request_hugepages + .save_restore
> + */
> +
> +#include "tst_test.h"
> +#include "tst_hugepage.h"
> +#include "tst_sys_conf.h"
> +
> +static const char * const save_restore[] = {
> +	"!/proc/sys/kernel/numa_balancing",
> +	NULL,
> +};
> +
> +static void do_test(void) {
> +
> +	int val, hpages;
> +
> +	tst_res(TINFO, "tst_hugepages = %u", tst_hugepages);
> +	SAFE_FILE_PRINTF("/proc/sys/kernel/numa_balancing", "1");
> +
> +	hpages = test.request_hugepages;
> +	SAFE_FILE_SCANF(PATH_NR_HPAGES, "%d", &val);
> +	if (val != hpages)
> +		tst_brk(TBROK, "nr_hugepages = %d, but expect %d", val, hpages);
> +	else
> +		tst_res(TPASS, "test .needs_hugepges");
> +
> +	hpages = tst_request_hugepages(3);
> +	SAFE_FILE_SCANF(PATH_NR_HPAGES, "%d", &val);
> +	if (val != hpages)
> +		tst_brk(TBROK, "nr_hugepages = %d, but expect %d", val, hpages);
> +	else
> +		tst_res(TPASS, "tst_request_hugepages");
> +}
> +
> +static struct tst_test test = {
> +	.test_all = do_test,
> +	.request_hugepages = 2,
> +	.save_restore = save_restore,
> +};
> diff --git a/lib/tst_hugepage.c b/lib/tst_hugepage.c
> new file mode 100644
> index 000000000..d37b45e3a
> --- /dev/null
> +++ b/lib/tst_hugepage.c
> @@ -0,0 +1,59 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2019 Red Hat, Inc.
> + */
> +
> +#define TST_NO_DEFAULT_MAIN
> +
> +#include "tst_test.h"
> +#include "tst_hugepage.h"
> +
> +unsigned int tst_hugepages;
> +
> +int tst_request_hugepages(int hpages)
> +{
> +	int val;
> +	long mem_avail, max_hpages;
> +
> +	if (access(PATH_HUGEPAGES, F_OK)) {
> +		tst_hugepages = 0;
> +		goto out;
> +	}
> +
> +	tst_hugepages = hpages;
> +
> +	SAFE_FILE_PRINTF("/proc/sys/vm/drop_caches", "3");
> +
> +	if (FILE_LINES_SCANF("/proc/meminfo",
> +				"MemAvailable: %ld", &mem_avail)) {
> +		/*
> +		 * Using "MemFree:" on kernel that doesn't have
> +		 * "MemAvailable:" in Meminfo
> +		 */
> +		tst_res(TINFO, "MemAvailable: not found in /proc/meminfo");
> +
> +		mem_avail = SAFE_READ_MEMINFO("MemFree:");
> +	}

I guess that we don't have to bother with MemAvailable here, since we do
drop the system caches the MemFree should be equal to MemAvailable. So I
would be for reading just MemFree unconditionally here.

If you agree with this change I can change it before applying.

> +	max_hpages = mem_avail / SAFE_READ_MEMINFO("Hugepagesize:");
> +
> +	if (hpages > max_hpages) {
> +		tst_res(TINFO, "Requested number(%d) of hugepages is too large, "
> +				"limiting to 80%% of the max hugepage count %ld",
> +				hpages, max_hpages);
> +		tst_hugepages = max_hpages * 0.8;
> +
> +		if (tst_hugepages < 1)
> +			goto out;
> +	}
> +
> +	tst_sys_conf_save("?/proc/sys/vm/nr_hugepages");
> +	SAFE_FILE_PRINTF(PATH_NR_HPAGES, "%d", tst_hugepages);
> +	SAFE_FILE_SCANF(PATH_NR_HPAGES, "%d", &val);
> +	if (val != tst_hugepages)
> +		tst_brk(TBROK, "nr_hugepages = %d, but expect %d", val, tst_hugepages);
> +
> +	tst_res(TINFO, "%d hugepage(s) reserved", tst_hugepages);
> +out:
> +	return tst_hugepages;
> +}
> diff --git a/lib/tst_test.c b/lib/tst_test.c
> index 8d7dee2cc..9a24cffc5 100644
> --- a/lib/tst_test.c
> +++ b/lib/tst_test.c
> @@ -890,6 +890,9 @@ static void do_setup(int argc, char *argv[])
>  	if (tst_test->all_filesystems)
>  		tst_test->needs_device = 1;
>  
> +	if (tst_test->request_hugepages)
> +		tst_request_hugepages(tst_test->request_hugepages);
> +
>  	setup_ipc();
>  
>  	if (tst_test->bufs)
> @@ -1006,8 +1009,7 @@ static void do_cleanup(void)
>  		tst_rmdir();
>  	}
>  
> -	if (tst_test->save_restore)
> -		tst_sys_conf_restore(0);
> +	tst_sys_conf_restore(0);
>  
>  	if (tst_test->restore_wallclock)
>  		tst_wallclock_restore();
> -- 
> 2.20.1
> 

> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp
Li Wang Feb. 19, 2020, 4:02 a.m. UTC | #4 
Cyril Hrubis <chrubis@suse.cz> wrote:

...
> > +
> > +             mem_avail = SAFE_READ_MEMINFO("MemFree:");
> > +     }
>
> I guess that we don't have to bother with MemAvailable here, since we do
> drop the system caches the MemFree should be equal to MemAvailable. So I
> would be for reading just MemFree unconditionally here.
>

+1 yes, that's right.


> If you agree with this change I can change it before applying.
>

Of course yes, feel free to do that (and remember to add the changes which
Petr suggested).
Petr Vorel Feb. 21, 2020, 12:16 p.m. UTC | #5 
Hi Li, Cyril,

> > +	if (FILE_LINES_SCANF("/proc/meminfo",
> > +				"MemAvailable: %ld", &mem_avail)) {
> > +		/*
> > +		 * Using "MemFree:" on kernel that doesn't have
> > +		 * "MemAvailable:" in Meminfo
> > +		 */
> > +		tst_res(TINFO, "MemAvailable: not found in /proc/meminfo");
> > +
> > +		mem_avail = SAFE_READ_MEMINFO("MemFree:");
> > +	}

> I guess that we don't have to bother with MemAvailable here, since we do
> drop the system caches the MemFree should be equal to MemAvailable. So I
> would be for reading just MemFree unconditionally here.

> If you agree with this change I can change it before applying.

Merged both patches with this change and my docs change.

Kind regards,
Petr
Li Wang Feb. 22, 2020, 3:02 a.m. UTC | #6 
On Fri, Feb 21, 2020 at 8:16 PM Petr Vorel <pvorel@suse.cz> wrote:

> Hi Li, Cyril,
>
> > > +   if (FILE_LINES_SCANF("/proc/meminfo",
> > > +                           "MemAvailable: %ld", &mem_avail)) {
> > > +           /*
> > > +            * Using "MemFree:" on kernel that doesn't have
> > > +            * "MemAvailable:" in Meminfo
> > > +            */
> > > +           tst_res(TINFO, "MemAvailable: not found in /proc/meminfo");
> > > +
> > > +           mem_avail = SAFE_READ_MEMINFO("MemFree:");
> > > +   }
>
> > I guess that we don't have to bother with MemAvailable here, since we do
> > drop the system caches the MemFree should be equal to MemAvailable. So I
> > would be for reading just MemFree unconditionally here.
>
> > If you agree with this change I can change it before applying.
>
> Merged both patches with this change and my docs change.
>

Thanks very much Petr. Btw, I added a commit to remove the surplus variable
'mem_avail'.(It's a tiny issue so I pushed directly:)
Petr Vorel Feb. 24, 2020, 8:40 a.m. UTC | #7 
Hi Li,

> > > If you agree with this change I can change it before applying.
> > Merged both patches with this change and my docs change.

> Thanks very much Petr. Btw, I added a commit to remove the surplus variable
> 'mem_avail'.(It's a tiny issue so I pushed directly:)
Thanks for fixing it and sorry for not amending your commit correctly.

Kind regards,
Petr
diff mbox series

Patch

diff --git a/doc/test-writing-guidelines.txt b/doc/test-writing-guidelines.txt
index 546bb7a49..fa7cb89c1 100644
--- a/doc/test-writing-guidelines.txt
+++ b/doc/test-writing-guidelines.txt
@@ -1933,6 +1933,64 @@  specified by the user plus some other heuristics.
 
 For full documentation see the comments in 'include/tst_fuzzy_sync.h'.
 
+2.2.34 Reserving hugepages
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Many of the ltp tests need to use hugepage in their testing, this allows the
+test can reserve hugepages from system only via .request_hugepages = xx.
+
+If set non-zero number of request_hugepages, test will try to reserve the
+expected number of hugepage for testing in setup phase. If system does not
+have enough hpage for using, it will try the best to reserve 80% available
+number of hpages. With success test stores the reserved hugepage number in
+'tst_hugepages. For the system without hugetlb supporting, variable
+'tst_hugepages' will be set to 0.
+
+Also, we do cleanup and restore work for the hpages resetting automatically.
+
+[source,c]
+-------------------------------------------------------------------------------
+#include "tst_test.h"
+
+static void run(void)
+{
+	...
+
+	if (tst_hugepages == test.request_hugepages)
+		TEST(do_hpage_test);
+	else
+		...
+	...
+}
+
+struct tst_test test = {
+	.test_all = run,
+	.request_hugepages = 2,
+	...
+};
+
+or,
+
+#include "tst_test.h"
+
+static void run(void)
+{
+	...
+}
+
+static void setup(void)
+{
+        if (tst_hugepages != test.requested_hugepages)
+                tst_brk(TCONF, "...");
+}
+
+struct tst_test test = {
+	.test_all = run,
+	.request_hugepages = 2,
+	...
+};
+-------------------------------------------------------------------------------
+
 2.3 Writing a testcase in shell
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/include/tst_hugepage.h b/include/tst_hugepage.h
new file mode 100644
index 000000000..10e0eaf47
--- /dev/null
+++ b/include/tst_hugepage.h
@@ -0,0 +1,29 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 Red Hat, Inc.
+ */
+
+#ifndef TST_HUGEPAGE__
+#define TST_HUGEPAGE__
+
+#define PATH_HUGEPAGES	"/sys/kernel/mm/hugepages/"
+#define PATH_NR_HPAGES	"/proc/sys/vm/nr_hugepages"
+
+/*
+ * Try the best to request a specified number of huge pages from system,
+ * it will store the reserved hpage number in tst_hugepages.
+ *
+ * Note: this depend on the status of system memory fragmentation.
+ */
+int tst_request_hugepages(int hpages);
+
+/*
+ * This variable is used for recording the number of hugepages which system can
+ * provides. It will be equal to 'hpages' if tst_request_hugepages on success,
+ * otherwise set it to a number of hugepages that we were able to reserve.
+ *
+ * If system does not support hugetlb, then it will be set to 0.
+ */
+extern unsigned int tst_hugepages;
+
+#endif /* TST_HUGEPAGE_H */
diff --git a/include/tst_test.h b/include/tst_test.h
index 21c7dfbdb..1026a422a 100644
--- a/include/tst_test.h
+++ b/include/tst_test.h
@@ -37,6 +37,7 @@ 
 #include "tst_coredump.h"
 #include "tst_buffers.h"
 #include "tst_capability.h"
+#include "tst_hugepage.h"
 
 /*
  * Reports testcase result.
@@ -148,6 +149,18 @@  struct tst_test {
 	 */
 	int all_filesystems:1;
 
+	/*
+	 * If set non-zero number of request_hugepages, test will try to reserve the
+	 * expected number of hugepage for testing in setup phase. If system does not
+	 * have enough hpage for using, it will try the best to reserve 80% available
+	 * number of hpages. With success test stores the reserved hugepage number in
+	 * 'tst_hugepages. For the system without hugetlb supporting, variable
+	 * 'tst_hugepages' will be set to 0.
+	 *
+	 * Also, we do cleanup and restore work for the hpages resetting automatically.
+	 */
+	unsigned int request_hugepages;
+
 	/*
 	 * If set non-zero denotes number of test variant, the test is executed
 	 * variants times each time with tst_variant set to different number.
diff --git a/lib/newlib_tests/.gitignore b/lib/newlib_tests/.gitignore
index d4aa4935f..ab3a92c4c 100644
--- a/lib/newlib_tests/.gitignore
+++ b/lib/newlib_tests/.gitignore
@@ -23,6 +23,7 @@  tst_strstatus
 test17
 test18
 test19
+test20
 tst_expiration_timer
 test_exec
 test_exec_child
diff --git a/lib/newlib_tests/test20.c b/lib/newlib_tests/test20.c
new file mode 100644
index 000000000..92e230976
--- /dev/null
+++ b/lib/newlib_tests/test20.c
@@ -0,0 +1,45 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 Li Wang <liwang@redhat.com>
+ */
+
+/*
+ * Tests .request_hugepages + .save_restore
+ */
+
+#include "tst_test.h"
+#include "tst_hugepage.h"
+#include "tst_sys_conf.h"
+
+static const char * const save_restore[] = {
+	"!/proc/sys/kernel/numa_balancing",
+	NULL,
+};
+
+static void do_test(void) {
+
+	int val, hpages;
+
+	tst_res(TINFO, "tst_hugepages = %u", tst_hugepages);
+	SAFE_FILE_PRINTF("/proc/sys/kernel/numa_balancing", "1");
+
+	hpages = test.request_hugepages;
+	SAFE_FILE_SCANF(PATH_NR_HPAGES, "%d", &val);
+	if (val != hpages)
+		tst_brk(TBROK, "nr_hugepages = %d, but expect %d", val, hpages);
+	else
+		tst_res(TPASS, "test .needs_hugepges");
+
+	hpages = tst_request_hugepages(3);
+	SAFE_FILE_SCANF(PATH_NR_HPAGES, "%d", &val);
+	if (val != hpages)
+		tst_brk(TBROK, "nr_hugepages = %d, but expect %d", val, hpages);
+	else
+		tst_res(TPASS, "tst_request_hugepages");
+}
+
+static struct tst_test test = {
+	.test_all = do_test,
+	.request_hugepages = 2,
+	.save_restore = save_restore,
+};
diff --git a/lib/tst_hugepage.c b/lib/tst_hugepage.c
new file mode 100644
index 000000000..d37b45e3a
--- /dev/null
+++ b/lib/tst_hugepage.c
@@ -0,0 +1,59 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 Red Hat, Inc.
+ */
+
+#define TST_NO_DEFAULT_MAIN
+
+#include "tst_test.h"
+#include "tst_hugepage.h"
+
+unsigned int tst_hugepages;
+
+int tst_request_hugepages(int hpages)
+{
+	int val;
+	long mem_avail, max_hpages;
+
+	if (access(PATH_HUGEPAGES, F_OK)) {
+		tst_hugepages = 0;
+		goto out;
+	}
+
+	tst_hugepages = hpages;
+
+	SAFE_FILE_PRINTF("/proc/sys/vm/drop_caches", "3");
+
+	if (FILE_LINES_SCANF("/proc/meminfo",
+				"MemAvailable: %ld", &mem_avail)) {
+		/*
+		 * Using "MemFree:" on kernel that doesn't have
+		 * "MemAvailable:" in Meminfo
+		 */
+		tst_res(TINFO, "MemAvailable: not found in /proc/meminfo");
+
+		mem_avail = SAFE_READ_MEMINFO("MemFree:");
+	}
+
+	max_hpages = mem_avail / SAFE_READ_MEMINFO("Hugepagesize:");
+
+	if (hpages > max_hpages) {
+		tst_res(TINFO, "Requested number(%d) of hugepages is too large, "
+				"limiting to 80%% of the max hugepage count %ld",
+				hpages, max_hpages);
+		tst_hugepages = max_hpages * 0.8;
+
+		if (tst_hugepages < 1)
+			goto out;
+	}
+
+	tst_sys_conf_save("?/proc/sys/vm/nr_hugepages");
+	SAFE_FILE_PRINTF(PATH_NR_HPAGES, "%d", tst_hugepages);
+	SAFE_FILE_SCANF(PATH_NR_HPAGES, "%d", &val);
+	if (val != tst_hugepages)
+		tst_brk(TBROK, "nr_hugepages = %d, but expect %d", val, tst_hugepages);
+
+	tst_res(TINFO, "%d hugepage(s) reserved", tst_hugepages);
+out:
+	return tst_hugepages;
+}
diff --git a/lib/tst_test.c b/lib/tst_test.c
index 8d7dee2cc..9a24cffc5 100644
--- a/lib/tst_test.c
+++ b/lib/tst_test.c
@@ -890,6 +890,9 @@  static void do_setup(int argc, char *argv[])
 	if (tst_test->all_filesystems)
 		tst_test->needs_device = 1;
 
+	if (tst_test->request_hugepages)
+		tst_request_hugepages(tst_test->request_hugepages);
+
 	setup_ipc();
 
 	if (tst_test->bufs)
@@ -1006,8 +1009,7 @@  static void do_cleanup(void)
 		tst_rmdir();
 	}
 
-	if (tst_test->save_restore)
-		tst_sys_conf_restore(0);
+	tst_sys_conf_restore(0);
 
 	if (tst_test->restore_wallclock)
 		tst_wallclock_restore();