File size: 2,295 Bytes
00d4f8c | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 | // Count how many pages of a file are resident in the page cache (mincore(2)).
// This is how we check "did the pager really bypass the page cache?": if the
// expert weights were served from cache, the model file would show up as resident.
//
// usage: pagecache_resident <file> [file...]
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
int main(int argc, char ** argv) {
if (argc < 2) { fprintf(stderr, "usage: %s [--evict] <file> [file...]\n", argv[0]); return 1; }
int argi = 1;
int evict = 0;
if (strcmp(argv[1], "--evict") == 0) { evict = 1; argi = 2; }
const long page = sysconf(_SC_PAGESIZE);
unsigned long long tot_r = 0, tot_s = 0;
for (int i = argi; i < argc; i++) {
const char * path = argv[i];
int fd = open(path, O_RDONLY);
if (fd < 0) { perror(path); return 1; }
struct stat st;
fstat(fd, &st);
if (evict) {
// per-file eviction of clean page-cache pages (no root needed)
posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
}
const size_t size = (size_t) st.st_size;
char * addr = (char *) mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
if (addr == MAP_FAILED) { perror("mmap"); return 1; }
const size_t npages = (size + page - 1) / page;
unsigned char * vec = (unsigned char *) malloc(npages);
if (mincore(addr, size, vec) != 0) { perror("mincore"); return 1; }
unsigned long long res = 0;
for (size_t p = 0; p < npages; p++) {
res += (vec[p] & 1);
}
free(vec);
munmap(addr, size);
close(fd);
const char * base = strrchr(path, '/');
base = base ? base + 1 : path;
printf("%-48s resident %8.3f GiB / %8.3f GiB (%5.1f %%)\n",
base, res * (double) page / 1073741824.0, size / 1073741824.0,
100.0 * (double) res * (double) page / (double) size);
tot_r += res * (unsigned long long) page;
tot_s += size;
}
if (argc > argi + 1) {
printf("%-48s resident %8.3f GiB / %8.3f GiB\n", "TOTAL",
tot_r / 1073741824.0, tot_s / 1073741824.0);
}
return 0;
}
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