nixos/nix
1
1
Fork 0
mirror of https://github.com/NixOS/nix.git synced 2025-12-07 01:21:00 +01:00
Code Activity

Merge pull request #5821 from edolstra/remove-affinity

Browse source 
Remove CPU locking
This commit is contained in:
Eelco Dolstra 2021-12-22 20:31:19 +01:00 • committed by GitHub
commit 7feb741e00
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
11 changed files with 5 additions and 100 deletions
Download patch file Download diff file Expand all files Collapse all files

70
src/libutil/affinity.cc
View file

@ -1,70 +0,0 @@
#include "types.hh"
#include "util.hh"
#include "affinity.hh"
#if __linux__
#include <sched.h>
#endif
namespace nix {
#if __linux__
static bool didSaveAffinity = false;
static cpu_set_t savedAffinity;
std::ostream& operator<<(std::ostream &os, const cpu_set_t &cset)
{
auto count = CPU_COUNT(&cset);
for (int i=0; i < count; ++i)
{
os << (CPU_ISSET(i,&cset) ? "1" : "0");
}
return os;
}
#endif
void setAffinityTo(int cpu)
{
#if __linux__
if (sched_getaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1) return;
didSaveAffinity = true;
debug(format("locking this thread to CPU %1%") % cpu);
cpu_set_t newAffinity;
CPU_ZERO(&newAffinity);
CPU_SET(cpu, &newAffinity);
if (sched_setaffinity(0, sizeof(cpu_set_t), &newAffinity) == -1)
printError("failed to lock thread to CPU %1%", cpu);
#endif
}
int lockToCurrentCPU()
{
#if __linux__
int cpu = sched_getcpu();
if (cpu != -1) setAffinityTo(cpu);
return cpu;
#else
return -1;
#endif
}
void restoreAffinity()
{
#if __linux__
if (!didSaveAffinity) return;
if (sched_setaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1)
{
std::ostringstream oss;
oss << savedAffinity;
printError("failed to restore CPU affinity %1%", oss.str());
}
#endif
}
}

9
src/libutil/affinity.hh
View file

@ -1,9 +0,0 @@
#pragma once
namespace nix {
void setAffinityTo(int cpu);
int lockToCurrentCPU();
void restoreAffinity();
}

3
src/libutil/thread-pool.cc
View file

@ -1,13 +1,10 @@
#include "thread-pool.hh"
#include "affinity.hh"
namespace nix {
ThreadPool::ThreadPool(size_t _maxThreads)
: maxThreads(_maxThreads)
{
restoreAffinity(); // FIXME
if (!maxThreads) {
maxThreads = std::thread::hardware_concurrency();
if (!maxThreads) maxThreads = 1;

4
src/libutil/util.cc
View file

@ -1,5 +1,4 @@
#include "util.hh"
#include "affinity.hh"
#include "sync.hh"
#include "finally.hh"
#include "serialise.hh"
@ -1004,7 +1003,6 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions & options)
if (options.dieWithParent && prctl(PR_SET_PDEATHSIG, SIGKILL) == -1)
throw SysError("setting death signal");
#endif
restoreAffinity();
fun();
} catch (std::exception & e) {
try {
@ -1675,8 +1673,6 @@ void restoreProcessContext(bool restoreMounts)
restoreMountNamespace();
}
restoreAffinity();
#if __linux__
if (savedStackSize) {
struct rlimit limit;

2
src/libutil/util.hh
View file

@ -300,7 +300,7 @@ void setStackSize(size_t stackSize);
/* Restore the original inherited Unix process context (such as signal
masks, stack size, CPU affinity). */
masks, stack size). */
void restoreProcessContext(bool restoreMounts = true);
/* Save the current mount namespace. Ignored if called more than