[patch] size optimization for mkswap.c, #2
Bernhard Fischer
rep.nop at aon.at
Sat Mar 18 12:11:58 UTC 2006
On Thu, Mar 16, 2006 at 02:29:49PM +0100, Bernhard Fischer wrote:
>Hi,
>
>Attached two patches do
>1) shrink mkswap a little bit
>2) make v0 support optional.
>
> text data bss dec hex filename
> 2093 8 28 2129 851 util-linux/mkswap.o.oorig
> 2044 8 28 2080 820 util-linux/mkswap.o.shrink
> 1698 4 28 1730 6c2 util-linux/mkswap.o.no-V0
(the above was with gcc-4.1, the one below is with 4.0.3, so the
original size differs a bit.)
Updated patch (thanks, Tito for thinking about getularg!)
2137 8 28 2173 87d util-linux/mkswap.o.orig
1890 8 28 1926 786 util-linux/mkswap.o.v0+v1
1560 4 28 1592 638 util-linux/mkswap.o.v1
I'll wait until after the mythical 1.1.1 :)
cheers,
Bernhard
-------------- next part --------------
Index: util-linux/mkswap.c
===================================================================
--- util-linux/mkswap.c (revision 14552)
+++ util-linux/mkswap.c (working copy)
@@ -59,9 +59,17 @@
static long PAGES = 0;
static int check = 0;
static int badpages = 0;
+#if ENABLE_FEATURE_MKSWAP_V0
static int version = -1;
-
#define MAKE_VERSION(p,q,r) (65536*(p) + 256*(q) + (r))
+#else
+#define version 1
+/* and make sure that we optimize away anything which would deal with checking
+ * the kernel revision as we have v1 support only anyway.
+ */
+#define MAKE_VERSION(p,q,r) 1
+#define get_kernel_revision() 1
+#endif
/*
* The definition of the union swap_header uses the constant PAGE_SIZE.
@@ -74,7 +82,7 @@
static struct swap_header_v1 {
char bootbits[1024]; /* Space for disklabel etc. */
- unsigned int version;
+ unsigned int swap_version;
unsigned int last_page;
unsigned int nr_badpages;
unsigned int padding[125];
@@ -172,23 +180,11 @@
return (r & m) != 0;
}
-
static void page_ok(int page)
{
- if (version == 0)
+ if (ENABLE_FEATURE_MKSWAP_V0) {
bit_set(signature_page, page);
-}
-
-static inline void page_bad(int page)
-{
- if (version == 0)
- bit_test_and_clear(signature_page, page);
- else {
- if (badpages == MAX_BADPAGES)
- bb_error_msg_and_die("too many bad pages");
- p->badpages[badpages] = page;
}
- badpages++;
}
static void check_blocks(void)
@@ -200,7 +196,7 @@
buffer = xmalloc(pagesize);
current_page = 0;
while (current_page < PAGES) {
- if (!check) {
+ if (!check && version == 0) {
page_ok(current_page++);
continue;
}
@@ -208,15 +204,23 @@
current_page * pagesize)
bb_error_msg_and_die("seek failed in check_blocks");
if ((do_seek = (pagesize != read(DEV, buffer, pagesize)))) {
- page_bad(current_page++);
+ current_page++;
+ if (version == 0)
+ bit_test_and_clear(signature_page, current_page);
+ else {
+ if (badpages == MAX_BADPAGES)
+ bb_error_msg_and_die("too many bad pages");
+ p->badpages[badpages] = current_page;
+ }
+ badpages++;
continue;
}
page_ok(current_page++);
}
- if (badpages == 1)
- printf("one bad page\n");
- else if (badpages > 1)
- printf("%d bad pages\n", badpages);
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(buffer);
+ if (badpages > 0)
+ printf("%d bad page%s\n", badpages, (badpages==1)?"":"s");
}
static long valid_offset(int fd, int offset)
@@ -249,17 +253,15 @@
}
/* return size in pages, to avoid integer overflow */
-static long get_size(const char *file)
+static inline long get_size(const char *file)
{
int fd;
long size;
- if ((fd = open(file, O_RDONLY)) < 0)
+ if ((fd = open(file, O_RDONLY)) < 0) /* TODO: bb_xopen3 */
bb_perror_msg_and_die("%s", file);
if (ioctl(fd, BLKGETSIZE, &size) >= 0) {
- int sectors_per_page = pagesize / 512;
-
- size /= sectors_per_page;
+ size /= pagesize / 512;
} else {
size = find_size(fd) / pagesize;
}
@@ -274,66 +276,53 @@
int sz;
int maxpages;
int goodpages;
- int offset;
+#ifdef __sparc__
int force = 0;
+#endif
init_signature_page(); /* get pagesize */
- while (argc-- > 1) {
- argv++;
- if (argv[0][0] != '-') {
- if (device_name) {
- int blocks_per_page = pagesize / 1024;
+ bb_opt_complementally = "?"; /* call bb_show_usage internally */
+ sz = bb_getopt_ulflags(argc, argv, "+cfv:", &tmp);
+ if (sz & 1)
+ check = 1;
+#ifdef __sparc__
+ if (sz & 2)
+ force = 1;
+#endif
+#if ENABLE_FEATURE_MKSWAP_V0
+ if (sz & 4) {
+ version = bb_xgetlarg(tmp, 10, 0, 1);
+ } else {
+ if (get_kernel_revision() < MAKE_VERSION(2, 1, 117))
+ version = 0;
+ else
+ version = 1;
+ }
+#endif
- PAGES = strtol(argv[0], &tmp, 0) / blocks_per_page;
- if (*tmp)
- bb_show_usage();
- } else
- device_name = argv[0];
+ argv += optind;
+ argc -= optind;
+
+ goodpages = pagesize / 1024; /* cache division */
+ while (argc--) {
+ if (device_name) {
+ PAGES = bb_xgetlarg(argv[0], 0, 10, sz * goodpages) / goodpages;
+ argc = 0; /* ignore any surplus args.. */
} else {
- switch (argv[0][1]) {
- case 'c':
- check = 1;
- break;
- case 'f':
- force = 1;
- break;
- case 'v':
- version = atoi(argv[0] + 2);
- break;
- default:
- bb_show_usage();
- }
+ device_name = argv[0];
+ sz = get_size(device_name);
+ argv++;
}
}
+
if (!device_name) {
- bb_error_msg("error: Nowhere to set up swap on?");
- bb_show_usage();
+ bb_error_msg_and_die("error: Nowhere to set up swap on?");
}
- sz = get_size(device_name);
if (!PAGES) {
PAGES = sz;
- } else if (PAGES > sz && !force) {
- bb_error_msg("error: size %ld is larger than device size %d",
- PAGES * (pagesize / 1024), sz * (pagesize / 1024));
- return EXIT_FAILURE;
}
- if (version == -1) {
- if (get_kernel_revision() < MAKE_VERSION(2, 1, 117))
- version = 0;
- else
- version = 1;
- }
- if (version != 0 && version != 1) {
- bb_error_msg("error: unknown version %d", version);
- bb_show_usage();
- }
- if (PAGES < 10) {
- bb_error_msg("error: swap area needs to be at least %ldkB",
- (long) (10 * pagesize / 1024));
- bb_show_usage();
- }
#if 0
maxpages = ((version == 0) ? V0_MAX_PAGES : V1_MAX_PAGES);
#else
@@ -350,7 +339,7 @@
if (PAGES > maxpages) {
PAGES = maxpages;
bb_error_msg("warning: truncating swap area to %ldkB",
- PAGES * pagesize / 1024);
+ PAGES * goodpages);
}
DEV = open(device_name, O_RDWR);
@@ -389,7 +378,7 @@
if (version == 0 && !bit_test_and_clear(signature_page, 0))
bb_error_msg_and_die("fatal: first page unreadable");
if (version == 1) {
- p->version = version;
+ p->swap_version = version;
p->last_page = PAGES - 1;
p->nr_badpages = badpages;
}
@@ -401,11 +390,12 @@
version, (long) (goodpages * pagesize));
write_signature((version == 0) ? "SWAP-SPACE" : "SWAPSPACE2");
- offset = ((version == 0) ? 0 : 1024);
- if (lseek(DEV, offset, SEEK_SET) != offset)
+ sz = ((version == 0) ? 0 : 1024); /* offset */
+ if (lseek(DEV, sz, SEEK_SET) != sz)
bb_error_msg_and_die("unable to rewind swap-device");
- if (write(DEV, (char *) signature_page + offset, pagesize - offset)
- != pagesize - offset)
+ goodpages = pagesize - sz; /* cache substraction */
+ if (write(DEV, (char *) signature_page + sz, goodpages)
+ != goodpages)
bb_error_msg_and_die("unable to write signature page");
/*
@@ -414,5 +404,9 @@
*/
if (fsync(DEV))
bb_error_msg_and_die("fsync failed");
+ if (ENABLE_FEATURE_CLEAN_UP) {
+ close(DEV);
+ free(signature_page);
+ }
return EXIT_SUCCESS;
}
Index: util-linux/Config.in
===================================================================
--- util-linux/Config.in (revision 14552)
+++ util-linux/Config.in (working copy)
@@ -288,6 +288,16 @@
Once you have created swap space using 'mkswap' you need to enable
the swap space using the 'swapon' utility.
+config CONFIG_FEATURE_MKSWAP_V0
+ bool " version 0 support"
+ default n
+ depends on CONFIG_MKSWAP
+# depends on CONFIG_MKSWAP && CONFIG_DEPRECATED
+ help
+ Enable support for the old v0 style.
+ If your kernel is older than 2.1.117, then v0 support is the
+ only option.
+
config CONFIG_MORE
bool "more"
default n
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