[PATCH 0/3] selftests/powerpc: ptrace/perf_hwbreak test fixes

[PATCH 0/3] selftests/powerpc: ptrace/perf_hwbreak test fixes

[Naveen N. Rao]

This series fixes two issues with the perf_hwbreak test:
- Test fails on systems with large number of cpus due to hitting the 
  resource limit for maximum number of open file descriptors.
- Test fails on systems running with lower SMT levels since it assumes 
  all cpus are online.

Fix those issues. The first patch is a small cleanup to aid subsequent 
fixes.

- Naveen


Naveen N. Rao (3):
  selftests/powerpc: Move perror closer to its use
  selftests/powerpc: Bump up rlimit for perf-hwbreak test
  selftests/powerpc: Account for offline cpus in perf-hwbreak test

 .../selftests/powerpc/ptrace/perf-hwbreak.c   | 78 +++++++++++++------
 1 file changed, 56 insertions(+), 22 deletions(-)


base-commit: eb05539de71d4784705d3e502d951ac17fea05e3
-- 
2.38.1

[PATCH 1/3] selftests/powerpc: Move perror closer to its use

[Naveen N. Rao]

Right now, if perf_event_open() fails for the systemwide tests, error
report is printed too late, sometimes after subsequent system calls.
Move use of perror() to the main function, just after the syscall.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 .../selftests/powerpc/ptrace/perf-hwbreak.c   | 21 +++++--------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c b/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c
index ecde2c199f3b18..ea5e14ecbf309f 100644
--- a/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c
+++ b/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c
@@ -146,6 +146,7 @@ static int perf_systemwide_event_open(int *fd, __u32 type, __u64 addr, __u64 len
 	for (i = 0; i < nprocs; i++) {
 		fd[i] = perf_cpu_event_open(i, type, addr, len);
 		if (fd[i] < 0) {
+			perror("perf_systemwide_event_open");
 			close_fds(fd, i);
 			return fd[i];
 		}
@@ -543,15 +544,12 @@ static int test_syswide_multi_diff_addr(void)
 	int ret;
 
 	ret = perf_systemwide_event_open(fd1, HW_BREAKPOINT_RW, (__u64)&a, (__u64)sizeof(a));
-	if (ret) {
-		perror("perf_systemwide_event_open");
+	if (ret)
 		exit(EXIT_FAILURE);
-	}
 
 	ret = perf_systemwide_event_open(fd2, HW_BREAKPOINT_RW, (__u64)&b, (__u64)sizeof(b));
 	if (ret) {
 		close_fds(fd1, nprocs);
-		perror("perf_systemwide_event_open");
 		exit(EXIT_FAILURE);
 	}
 
@@ -590,15 +588,12 @@ static int test_syswide_multi_same_addr(void)
 	int ret;
 
 	ret = perf_systemwide_event_open(fd1, HW_BREAKPOINT_RW, (__u64)&a, (__u64)sizeof(a));
-	if (ret) {
-		perror("perf_systemwide_event_open");
+	if (ret)
 		exit(EXIT_FAILURE);
-	}
 
 	ret = perf_systemwide_event_open(fd2, HW_BREAKPOINT_RW, (__u64)&a, (__u64)sizeof(a));
 	if (ret) {
 		close_fds(fd1, nprocs);
-		perror("perf_systemwide_event_open");
 		exit(EXIT_FAILURE);
 	}
 
@@ -637,15 +632,12 @@ static int test_syswide_multi_diff_addr_ro_wo(void)
 	int ret;
 
 	ret = perf_systemwide_event_open(fd1, HW_BREAKPOINT_W, (__u64)&a, (__u64)sizeof(a));
-	if (ret) {
-		perror("perf_systemwide_event_open");
+	if (ret)
 		exit(EXIT_FAILURE);
-	}
 
 	ret = perf_systemwide_event_open(fd2, HW_BREAKPOINT_R, (__u64)&b, (__u64)sizeof(b));
 	if (ret) {
 		close_fds(fd1, nprocs);
-		perror("perf_systemwide_event_open");
 		exit(EXIT_FAILURE);
 	}
 
@@ -684,15 +676,12 @@ static int test_syswide_multi_same_addr_ro_wo(void)
 	int ret;
 
 	ret = perf_systemwide_event_open(fd1, HW_BREAKPOINT_W, (__u64)&a, (__u64)sizeof(a));
-	if (ret) {
-		perror("perf_systemwide_event_open");
+	if (ret)
 		exit(EXIT_FAILURE);
-	}
 
 	ret = perf_systemwide_event_open(fd2, HW_BREAKPOINT_R, (__u64)&a, (__u64)sizeof(a));
 	if (ret) {
 		close_fds(fd1, nprocs);
-		perror("perf_systemwide_event_open");
 		exit(EXIT_FAILURE);
 	}
 
-- 
2.38.1

[PATCH 2/3] selftests/powerpc: Bump up rlimit for perf-hwbreak test

[Naveen N. Rao]

The systemwide perf hardware breakpoint test tries to open a perf event
on each cpu. On large systems, we run out of file descriptors and fail
the test. Instead, have the test set the file descriptor limit to an
arbitraty high value.

Reported-by: Rohan Deshpande <rohan_d@linux.vnet.ibm.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 .../testing/selftests/powerpc/ptrace/perf-hwbreak.c  | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c b/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c
index ea5e14ecbf309f..866e5be48ee33a 100644
--- a/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c
+++ b/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c
@@ -26,6 +26,7 @@
 #include <sys/ioctl.h>
 #include <sys/wait.h>
 #include <sys/ptrace.h>
+#include <sys/resource.h>
 #include <sys/sysinfo.h>
 #include <asm/ptrace.h>
 #include <elf.h>
@@ -140,8 +141,19 @@ static void disable_fds(int *fd, int n)
 
 static int perf_systemwide_event_open(int *fd, __u32 type, __u64 addr, __u64 len)
 {
+	struct rlimit rlim;
 	int i = 0;
 
+	if (getrlimit(RLIMIT_NOFILE, &rlim)) {
+		perror("getrlimit");
+		return -1;
+	}
+	rlim.rlim_cur = 65536;
+	if (setrlimit(RLIMIT_NOFILE, &rlim)) {
+		perror("setrlimit");
+		return -1;
+	}
+
 	/* Assume online processors are 0 to nprocs for simplisity */
 	for (i = 0; i < nprocs; i++) {
 		fd[i] = perf_cpu_event_open(i, type, addr, len);
-- 
2.38.1

Re: [PATCH 2/3] selftests/powerpc: Bump up rlimit for perf-hwbreak test

[Rohan Deshpande]

Hi,

I have verified and tested this patch. No issues found. Changes look good.

Tested-by: Rohan Deshpande <rohan_d@linux.vnet.ibm.com>

[PATCH 3/3] selftests/powerpc: Account for offline cpus in perf-hwbreak test

[Naveen N. Rao]

For systemwide tests, use online cpu mask to only open events on online
cpus. This enables this test to work on systems in lower SMT modes.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 .../selftests/powerpc/ptrace/perf-hwbreak.c   | 45 ++++++++++++++++---
 1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c b/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c
index 866e5be48ee33a..f75739bbad28cd 100644
--- a/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c
+++ b/tools/testing/selftests/powerpc/ptrace/perf-hwbreak.c
@@ -17,8 +17,11 @@
  * Copyright (C) 2018 Michael Neuling, IBM Corporation.
  */
 
+#define _GNU_SOURCE
+
 #include <unistd.h>
 #include <assert.h>
+#include <sched.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <signal.h>
@@ -141,8 +144,10 @@ static void disable_fds(int *fd, int n)
 
 static int perf_systemwide_event_open(int *fd, __u32 type, __u64 addr, __u64 len)
 {
+	int i, ncpus, cpu, ret = 0;
 	struct rlimit rlim;
-	int i = 0;
+	cpu_set_t *mask;
+	size_t size;
 
 	if (getrlimit(RLIMIT_NOFILE, &rlim)) {
 		perror("getrlimit");
@@ -154,16 +159,44 @@ static int perf_systemwide_event_open(int *fd, __u32 type, __u64 addr, __u64 len
 		return -1;
 	}
 
-	/* Assume online processors are 0 to nprocs for simplisity */
-	for (i = 0; i < nprocs; i++) {
-		fd[i] = perf_cpu_event_open(i, type, addr, len);
+	ncpus = get_nprocs_conf();
+	size = CPU_ALLOC_SIZE(ncpus);
+	mask = CPU_ALLOC(ncpus);
+	if (!mask) {
+		perror("malloc");
+		return -1;
+	}
+
+	CPU_ZERO_S(size, mask);
+
+	if (sched_getaffinity(0, size, mask)) {
+		perror("sched_getaffinity");
+		ret = -1;
+		goto done;
+	}
+
+	for (i = 0, cpu = 0; i < nprocs && cpu < ncpus; cpu++) {
+		if (!CPU_ISSET_S(cpu, size, mask))
+			continue;
+		fd[i] = perf_cpu_event_open(cpu, type, addr, len);
 		if (fd[i] < 0) {
 			perror("perf_systemwide_event_open");
 			close_fds(fd, i);
-			return fd[i];
+			ret = fd[i];
+			goto done;
 		}
+		i++;
 	}
-	return 0;
+
+	if (i < nprocs) {
+		printf("Error: Number of online cpus reduced since start of test: %d < %d\n", i, nprocs);
+		close_fds(fd, i);
+		ret = -1;
+	}
+
+done:
+	CPU_FREE(mask);
+	return ret;
 }
 
 static inline bool breakpoint_test(int len)
-- 
2.38.1

Re: [PATCH 0/3] selftests/powerpc: ptrace/perf_hwbreak test fixes

[Michael Ellerman]

On Tue, 22 Nov 2022 12:10:51 +0530, Naveen N. Rao wrote:
> This series fixes two issues with the perf_hwbreak test:
> - Test fails on systems with large number of cpus due to hitting the
>   resource limit for maximum number of open file descriptors.
> - Test fails on systems running with lower SMT levels since it assumes
>   all cpus are online.
> 
> Fix those issues. The first patch is a small cleanup to aid subsequent
> fixes.
> 
> [...]

Applied to powerpc/next.

[1/3] selftests/powerpc: Move perror closer to its use
      https://git.kernel.org/powerpc/c/71ae6305ad41cfd1ac5aa91d356e71c7a537df2e
[2/3] selftests/powerpc: Bump up rlimit for perf-hwbreak test
      https://git.kernel.org/powerpc/c/616ad3f4aac287c48b66c92cb777395b4465ed4f
[3/3] selftests/powerpc: Account for offline cpus in perf-hwbreak test
      https://git.kernel.org/powerpc/c/260095926d3956071c6699a28824c3f0fa7cd97a

cheers