/* $NetBSD: fincore.c,v 1.2 2024/11/03 10:43:27 rillig Exp $ */
/*-
* Copyright (c) 2011 YAMAMOTO Takashi,
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* a utility to query which file pages are cached
*
* inspired by:
*
http://net.doit.wisc.edu/~plonka/fincore/
*
http://www.usenix.org/events/lisa07/tech/plonka.html
*/
#include <sys/cdefs.h>
#if defined(__NetBSD__)
#ifndef lint
__RCSID("$NetBSD: fincore.c,v 1.2 2024/11/03 10:43:27 rillig Exp $");
#endif /* not lint */
#endif /* defined(__NetBSD__) */
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <err.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#if !defined(__arraycount)
#define __arraycount(a) (sizeof(a)/sizeof(*a))
#endif /* !defined(__arraycount) */
size_t page_size;
bool do_summary;
bool be_quiet;
/*
* fincore: query which pages of the file are in-core.
*
* this function is intended to be compatible with:
*
http://lwn.net/Articles/371538/
*
http://libprefetch.cs.ucla.edu/
*
* while this can be implemented in kernel much more efficiently, i'm not
* sure if making this a syscall in 2011 is a good idea. this API does not
* seem scalable for sparsely cached huge files. the expected scalability
* has been changed since the time when mincore was invented.
*
* some references:
*
http://wiki.postgresql.org/images/a/a2/Pgfincore_pgday10.pdf
*/
static int
fincore(int fd, off_t startoff, off_t endoff, unsigned char *vec)
{
off_t off;
size_t chunk_size;
for (off = startoff; off < endoff;
off += chunk_size, vec += chunk_size / page_size) {
void *vp;
chunk_size = MIN((off_t)(1024 * page_size), endoff - off);
vp = mmap(NULL, chunk_size, PROT_NONE, MAP_FILE|MAP_SHARED,
fd, off);
if (vp == MAP_FAILED) {
return -1;
}
if (mincore(vp, chunk_size,
#if !defined(__linux__)
(char *)
#endif /* !defined(__linux__) */
vec)) {
munmap(vp, chunk_size);
return -1;
}
if (munmap(vp, chunk_size)) {
return -1;
}
}
return 0;
}
static void
do_file(const char *name)
{
unsigned char vec[4096];
struct stat st;
uintmax_t n; /* number of pages in-core */
off_t off;
size_t chunk_size;
int fd;
bool header_done = false;
fd = open(name, O_RDONLY);
if (fd == -1) {
err(EXIT_FAILURE, "open %s", name);
}
if (fstat(fd, &st)) {
err(EXIT_FAILURE, "fstat %s", name);
}
n = 0;
for (off = 0; off < st.st_size; off += chunk_size) {
unsigned int i;
chunk_size = MIN(__arraycount(vec) * page_size,
roundup(st.st_size - off, page_size));
if (fincore(fd, off, off + chunk_size, vec)) {
printf("\n");
err(EXIT_FAILURE, "fincore %s", name);
}
for (i = 0; i < chunk_size / page_size; i++) {
if (vec[i] == 0) {
continue;
}
if (!do_summary) {
if (!header_done) {
printf("%s:", name);
header_done = true;
}
printf(" %ju",
(uintmax_t)(off / page_size + i));
}
n++;
}
}
close(fd);
if (do_summary && (n != 0 || !be_quiet)) {
const uintmax_t total = howmany(st.st_size, page_size);
const double pct = (total != 0) ? ((double)n / total * 100) : 0;
if (!header_done) {
printf("%s:", name);
header_done = true;
}
printf(" %ju / %ju in-core pages (%0.2f%%)", n, total, pct);
}
if (header_done) {
printf("\n");
} else if (!be_quiet) {
printf("%s: \n", name);
}
}
int
/*ARGSUSED*/
main(int argc, char *argv[])
{
long l;
int ch;
while ((ch = getopt(argc, argv, "sq")) != -1) {
switch (ch) {
case 's':
do_summary = true;
break;
case 'q':
be_quiet = true;
break;
default:
exit(EXIT_FAILURE);
}
}
l = sysconf(_SC_PAGESIZE);
if (l == -1) {
/*
* sysconf doesn't always set errno. bad API.
*/
errx(EXIT_FAILURE, "_SC_PAGESIZE");
}
page_size = (size_t)l;
argc -= optind;
argv += optind;
while (argc > 0) {
do_file(argv[0]);
argc--;
argv++;
}
return EXIT_SUCCESS;
}
