Skip to content

fix(linux): respect cgroup cpuset when pinning fuzzing threads #539

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
claudijd wants to merge 1 commit into
base: master
Choose a base branch
from
+41 −1
Open

fix(linux): respect cgroup cpuset when pinning fuzzing threads #539

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
42 changes: 41 additions & 1 deletion libhfcommon/util.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -92,12 +92,43 @@ bool util_PinThreadToCPUs(uint32_t threadno, uint32_t cpucnt) {
return true;
}

#if defined(_HF_ARCH_LINUX)
/*
* Query the CPUs this process can actually be scheduled on (respects
* cgroup cpuset restrictions), rather than assuming CPU IDs 0..num_cpus-1
* are free based on sysconf(_SC_NPROCESSORS_ONLN). Under a container/cgroup
* that limits CPU via quota/shares but not cpuset (a common configuration),
* sysconf() still reports the full host CPU count, so pinning by raw index
* causes every concurrent instance on that host to independently pick the
* same physical CPUs -- turning "N CPUs per instance" into cross-instance
* contention instead of parallelism, while the rest of the host's CPUs sit
* idle. Enumerating the real affinity mask and indexing into it is a no-op
* wherever the process is unconstrained (the common case, where the mask
* already lists CPUs 0..num_cpus-1), and correct wherever it's
* cpuset-restricted.
*/
cpu_set_t avail_set;
CPU_ZERO(&avail_set);
if (sched_getaffinity(0, sizeof(avail_set), &avail_set) != 0) {
PLOG_W("sched_getaffinity() failed");
return false;
}

uint32_t avail_cpus[CPU_SETSIZE];
uint32_t num_cpus = 0;
for (int i = 0; i < CPU_SETSIZE; i++) {
if (CPU_ISSET(i, &avail_set)) {
avail_cpus[num_cpus++] = (uint32_t)i;
}
}
#else /* defined(_HF_ARCH_LINUX) */
long r = sysconf(_SC_NPROCESSORS_ONLN);
if (r == -1) {
PLOG_W("sysconf(_SC_NPROCESSORS_ONLN) failed");
return false;
}
uint32_t num_cpus = (uint32_t)r;
#endif /* defined(_HF_ARCH_LINUX) */

if (cpucnt > num_cpus) {
LOG_W("Requested CPUs (%" PRIu32 ") > available CPUs (%" PRIu32 ") for thread #%" PRIu32,
Expand All @@ -107,9 +138,16 @@ bool util_PinThreadToCPUs(uint32_t threadno, uint32_t cpucnt) {

uint32_t start_cpu = (threadno * cpucnt) % num_cpus;
uint32_t end_cpu = (start_cpu + cpucnt - 1U) % num_cpus;
#if defined(_HF_ARCH_LINUX)
LOG_D("Setting CPU affinity for the current thread #%" PRIu32 " to %" PRIu32
" consecutive CPUs out of %" PRIu32 " actually schedulable, (cpu:%" PRIu32 "-cpu:%" PRIu32
")",
threadno, cpucnt, num_cpus, avail_cpus[start_cpu], avail_cpus[end_cpu]);
#else /* defined(_HF_ARCH_LINUX) */
LOG_D("Setting CPU affinity for the current thread #%" PRIu32 " to %" PRIu32
" consecutive CPUs, (start:%" PRIu32 "-end:%" PRIu32 ") total_cpus:%" PRIu32,
threadno, cpucnt, start_cpu, end_cpu, num_cpus);
#endif /* defined(_HF_ARCH_LINUX) */

#if defined(_HF_ARCH_LINUX) || defined(__FreeBSD__) || defined(_HF_ARCH_NETBSD) || \
defined(__DragonFly__)
Expand All @@ -126,7 +164,9 @@ bool util_PinThreadToCPUs(uint32_t threadno, uint32_t cpucnt) {
#endif /* defined(_HF_ARCH_NETBSD) */

for (uint32_t i = 0; i < cpucnt; i++) {
#if defined(_HF_ARCH_NETBSD)
#if defined(_HF_ARCH_LINUX)
CPU_SET(avail_cpus[(start_cpu + i) % num_cpus], &set);
#elif defined(_HF_ARCH_NETBSD)
cpuset_set((start_cpu + i) % num_cpus, set);
#else /* defined((_HF_ARCH_NETBSD) */
CPU_SET((start_cpu + i) % num_cpus, &set);
Expand Down