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Commit 229ab0cb authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Paul E. McKenney
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rcutorture: Make initrd/init execute in userspace 



Currently, the initrd/init script and executable remain blocked almost
all the time.  However, it is necessary to test nohz_full userspace
execution, which both variants of initrd/init fail to do.  This commit
therefore causes initrd/init to spend about a millisecond per second
executing in userspace.

Reported-by: default avatarJosh Triplett <josh@joshtriplett.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 38e63042

tools/testing/selftests/rcutorture/bin/mkinitrd.sh

+39 −4
Original line number Diff line number Diff line
@@ -39,9 +39,22 @@ mkdir $T 


cat > $T/init << '__EOF___'

#!/bin/sh

# Run in userspace a few milliseconds every second.  This helps to

# exercise the NO_HZ_FULL portions of RCU.

while :

do

	sleep 1000000

	q=

	for i in \

		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \

		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \

		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \

		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \

		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \

		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a

	do

		q="$q $i"

	done

	sleep 1

done

__EOF___
@@ -70,15 +83,37 @@ mkdir initrd 
cd initrd

cat > init.c << '___EOF___'

#include <unistd.h>

#include <sys/time.h>



volatile unsigned long delaycount;



int main(int argc, int argv[])

{

	for (;;)

		sleep(1000*1000*1000); /* One gigasecond is ~30 years. */

	int i;

	struct timeval tv;

	struct timeval tvb;



	for (;;) {

		sleep(1);

		/* Need some userspace time. */

		if (gettimeofday(&tvb, NULL))

			continue;

		do {

			for (i = 0; i < 1000 * 100; i++)

				delaycount = i * i;

			if (gettimeofday(&tv, NULL))

				break;

			tv.tv_sec -= tvb.tv_sec;

			if (tv.tv_sec > 1)

				break;

			tv.tv_usec += tv.tv_sec * 1000 * 1000;

			tv.tv_usec -= tvb.tv_usec;

		} while (tv.tv_usec < 1000);

	}

	return 0;

}

___EOF___

gcc -static -Os -o init init.c

cc -static -Os -o init init.c

strip init

rm init.c

echo "Done creating a statically linked C-language initrd"