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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>#include <stdio.h>#include <stdlib.h>#include <sys/prctl.h>#include <sys/wait.h>#include <unistd.h>
#include "../tests.h"
static int loops = 100;static char buf;int context_switch_loop_work = 1234;
#define write_block(fd) \ do { \ if (write(fd, &buf, 1) <= 0) \ return 1; \ } while (0)
#define read_block(fd) \ do { \ if (read(fd, &buf, 1) <= 0) \ return 1; \ } while (0)
/* Not static to avoid LTO clobbering the function name */int context_switch_loop_proc1(int in_fd, int out_fd);int context_switch_loop_proc1(int in_fd, int out_fd){ for (int i = 0; i < loops; i++) { read_block(in_fd); context_switch_loop_work += i * 3; write_block(out_fd); } return 0;}
int context_switch_loop_proc2(int in_fd, int out_fd);int context_switch_loop_proc2(int in_fd, int out_fd){ for (int i = 0; i < loops; i++) { write_block(out_fd); context_switch_loop_work += i * 7; read_block(in_fd); } return 0;}
/* * Launches two processes that take turns to execute a multiplication N times */static int context_switch_loop(int argc, const char **argv){ int a_to_b[2], b_to_a[2]; pid_t proc1_pid; int status; int ret;
if (argc > 0) { loops = atoi(argv[0]); if (loops < 0) { fprintf(stderr, "Invalid number of loops: %s\n", argv[0]); return 1; } }
if (pipe(a_to_b) || pipe(b_to_a)) { perror("Pipe error"); return 1; }
proc1_pid = fork(); if (proc1_pid < 0) { perror("Fork error"); return 1; }
if (!proc1_pid) { close(a_to_b[0]); close(b_to_a[1]); prctl(PR_SET_NAME, "proc1", 0, 0, 0); ret = context_switch_loop_proc1(b_to_a[0], a_to_b[1]); close(a_to_b[1]); close(b_to_a[0]); exit(ret); }
close(a_to_b[1]); close(b_to_a[0]); prctl(PR_SET_NAME, "proc2", 0, 0, 0); ret = context_switch_loop_proc2(a_to_b[0], b_to_a[1]); close(a_to_b[0]); close(b_to_a[1]);
if (ret) { kill(proc1_pid, SIGKILL); return ret; }
if (waitpid(proc1_pid, &status, 0) != proc1_pid || !WIFEXITED(status) || WEXITSTATUS(status)) return 1;
return 0;}
DEFINE_WORKLOAD(context_switch_loop);