Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
selftests/seccomp: Pin benchmark to single CPU
The seccomp benchmark test (for validating the benefit of bitmaps) can
be sensitive to scheduling speed, so pin the process to a single CPU,
which appears to significantly improve reliability, and loosen the
"close enough" checking to allow up to 10% variance instead of 1%.
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402061002.3a8722fd-oliver.sang@intel.com
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
+36
-2
+36
-2
tools/testing/selftests/seccomp/seccomp_benchmark.c
+36
-2
tools/testing/selftests/seccomp/seccomp_benchmark.c
···
4
4
*/
5
5
#define _GNU_SOURCE
6
6
#include <assert.h>
7
+
#include <err.h>
7
8
#include <limits.h>
9
+
#include <sched.h>
8
10
#include <stdbool.h>
9
11
#include <stddef.h>
10
12
#include <stdio.h>
···
78
76
79
77
bool approx(int i_one, int i_two)
80
78
{
81
-
double one = i_one, one_bump = one * 0.01;
82
-
double two = i_two, two_bump = two * 0.01;
79
+
/*
80
+
* This continues to be a noisy test. Instead of a 1% comparison
81
+
* go with 10%.
82
+
*/
83
+
double one = i_one, one_bump = one * 0.1;
84
+
double two = i_two, two_bump = two * 0.1;
83
85
84
86
one_bump = one + MAX(one_bump, 2.0);
85
87
two_bump = two + MAX(two_bump, 2.0);
···
125
119
return good ? 0 : 1;
126
120
}
127
121
122
+
/* Pin to a single CPU so the benchmark won't bounce around the system. */
123
+
void affinity(void)
124
+
{
125
+
long cpu;
126
+
ulong ncores = sysconf(_SC_NPROCESSORS_CONF);
127
+
cpu_set_t *setp = CPU_ALLOC(ncores);
128
+
ulong setsz = CPU_ALLOC_SIZE(ncores);
129
+
130
+
/*
131
+
* Totally unscientific way to avoid CPUs that might be busier:
132
+
* choose the highest CPU instead of the lowest.
133
+
*/
134
+
for (cpu = ncores - 1; cpu >= 0; cpu--) {
135
+
CPU_ZERO_S(setsz, setp);
136
+
CPU_SET_S(cpu, setsz, setp);
137
+
if (sched_setaffinity(getpid(), setsz, setp) == -1)
138
+
continue;
139
+
printf("Pinned to CPU %lu of %lu\n", cpu + 1, ncores);
140
+
goto out;
141
+
}
142
+
fprintf(stderr, "Could not set CPU affinity -- calibration may not work well");
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+
144
+
out:
145
+
CPU_FREE(setp);
146
+
}
147
+
128
148
int main(int argc, char *argv[])
129
149
{
130
150
struct sock_filter bitmap_filter[] = {
···
184
152
/* Avoid using "sysctl" which may not be installed. */
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153
system("grep -H . /proc/sys/net/core/bpf_jit_enable");
186
154
system("grep -H . /proc/sys/net/core/bpf_jit_harden");
155
+
156
+
affinity();
187
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if (argc > 1)
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159
samples = strtoull(argv[1], NULL, 0);