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authorXin LI <delphij@FreeBSD.org>2020-07-04 18:37:04 +0000
committerXin LI <delphij@FreeBSD.org>2020-07-04 18:37:04 +0000
commit33c2d974d03d3c5fdbafd3c72611af84c4b78dc6 (patch)
treef980e621c6c370f288d8a63af6f5e637de9a6324 /sbin/newfs_msdos
parent6ef8f9d28a6960eb0a301e5d691879b808fa9941 (diff)
downloadsrc-33c2d974d03d3c5fdbafd3c72611af84c4b78dc6.tar.gz
src-33c2d974d03d3c5fdbafd3c72611af84c4b78dc6.zip
Gather writes to larger chunks (MAXPHYS) instead of issuing them in
sectors. On my SanDisk Cruzer Blade 16GB USB stick this made formatting much faster: x before + after +--------------------------------------------------------------------------+ |+ | |+ x | |+ x x| |A MA|| +--------------------------------------------------------------------------+ N Min Max Median Avg Stddev x 3 15.89 16.38 16 16.09 0.2570992 + 3 0.32 0.37 0.35 0.34666667 0.025166115 Difference at 95.0% confidence -15.7433 +/- 0.414029 -97.8455% +/- 0.25668% (Student's t, pooled s = 0.182665) Reviewed by: emaste MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D24508
Notes
Notes: svn path=/head/; revision=362936
Diffstat (limited to 'sbin/newfs_msdos')
-rw-r--r--sbin/newfs_msdos/mkfs_msdos.c76
1 files changed, 58 insertions, 18 deletions
diff --git a/sbin/newfs_msdos/mkfs_msdos.c b/sbin/newfs_msdos/mkfs_msdos.c
index 77e8b19d3338..3f4c0a14b50b 100644
--- a/sbin/newfs_msdos/mkfs_msdos.c
+++ b/sbin/newfs_msdos/mkfs_msdos.c
@@ -64,6 +64,7 @@ static const char rcsid[] =
#define DOSMAGIC 0xaa55 /* DOS magic number */
#define MINBPS 512 /* minimum bytes per sector */
+#define MAXBPS 4096 /* maximum bytes per sector */
#define MAXSPC 128 /* maximum sectors per cluster */
#define MAXNFT 16 /* maximum number of FATs */
#define DEFBLK 4096 /* default block size */
@@ -77,6 +78,25 @@ static const char rcsid[] =
#define MAXCLS16 0xfff4U /* maximum FAT16 clusters */
#define MAXCLS32 0xffffff4U /* maximum FAT32 clusters */
+#ifndef CTASSERT
+#define CTASSERT(x) _CTASSERT(x, __LINE__)
+#define _CTASSERT(x, y) __CTASSERT(x, y)
+#define __CTASSERT(x, y) typedef char __assert_ ## y [(x) ? 1 : -1]
+#endif
+
+/*
+ * For better performance, we want to write larger chunks instead of
+ * individual sectors (the size can only be 512, 1024, 2048 or 4096
+ * bytes). Assert that MAXPHYS can always hold an integer number of
+ * sectors by asserting that both are power of two numbers and the
+ * MAXPHYS is greater than MAXBPS.
+ */
+CTASSERT(powerof2(MAXPHYS));
+CTASSERT(powerof2(MAXBPS));
+CTASSERT(MAXPHYS > MAXBPS);
+
+const static ssize_t chunksize = MAXPHYS;
+
#define mincls(fat) ((fat) == 12 ? MINCLS12 : \
(fat) == 16 ? MINCLS16 : \
MINCLS32)
@@ -243,6 +263,7 @@ mkfs_msdos(const char *fname, const char *dtype, const struct msdos_options *op)
struct bsx *bsx;
struct de *de;
u_int8_t *img;
+ u_int8_t *physbuf, *physbuf_end;
const char *bname;
ssize_t n;
time_t now;
@@ -252,7 +273,7 @@ mkfs_msdos(const char *fname, const char *dtype, const struct msdos_options *op)
int fd, fd1, rv;
struct msdos_options o = *op;
- img = NULL;
+ physbuf = NULL;
rv = -1;
fd = fd1 = -1;
@@ -343,13 +364,11 @@ mkfs_msdos(const char *fname, const char *dtype, const struct msdos_options *op)
bpb.bpbSecPerClust = 64; /* otherwise 32k */
}
}
- if (!powerof2(bpb.bpbBytesPerSec)) {
- warnx("bytes/sector (%u) is not a power of 2", bpb.bpbBytesPerSec);
- goto done;
- }
- if (bpb.bpbBytesPerSec < MINBPS) {
- warnx("bytes/sector (%u) is too small; minimum is %u",
- bpb.bpbBytesPerSec, MINBPS);
+ if (bpb.bpbBytesPerSec < MINBPS ||
+ bpb.bpbBytesPerSec > MAXBPS ||
+ !powerof2(bpb.bpbBytesPerSec)) {
+ warnx("Invalid bytes/sector (%u): must be 512, 1024, 2048 or 4096",
+ bpb.bpbBytesPerSec);
goto done;
}
@@ -621,11 +640,14 @@ mkfs_msdos(const char *fname, const char *dtype, const struct msdos_options *op)
tm = localtime(&now);
}
-
- if (!(img = malloc(bpb.bpbBytesPerSec))) {
+ physbuf = malloc(chunksize);
+ if (physbuf == NULL) {
warn(NULL);
goto done;
}
+ physbuf_end = physbuf + chunksize;
+ img = physbuf;
+
dir = bpb.bpbResSectors + (bpb.bpbFATsecs ? bpb.bpbFATsecs :
bpb.bpbBigFATsecs) * bpb.bpbFATs;
memset(&si_sa, 0, sizeof(si_sa));
@@ -750,19 +772,37 @@ mkfs_msdos(const char *fname, const char *dtype, const struct msdos_options *op)
(u_int)tm->tm_mday;
mk2(de->deMDate, x);
}
- if ((n = write(fd, img, bpb.bpbBytesPerSec)) == -1) {
- warn("%s", fname);
- goto done;
- }
- if ((unsigned)n != bpb.bpbBytesPerSec) {
- warnx("%s: can't write sector %u", fname, lsn);
- goto done;
+ /*
+ * Issue a write of chunksize once we have collected
+ * enough sectors.
+ */
+ img += bpb.bpbBytesPerSec;
+ if (img >= physbuf_end) {
+ n = write(fd, physbuf, chunksize);
+ if (n != chunksize) {
+ warnx("%s: can't write sector %u", fname, lsn);
+ goto done;
+ }
+ img = physbuf;
}
}
+ /*
+ * Write remaining sectors, if the last write didn't end
+ * up filling a whole chunk.
+ */
+ if (img != physbuf) {
+ ssize_t tailsize = img - physbuf;
+
+ n = write(fd, physbuf, tailsize);
+ if (n != tailsize) {
+ warnx("%s: can't write sector %u", fname, lsn);
+ goto done;
+ }
+ }
}
rv = 0;
done:
- free(img);
+ free(physbuf);
if (fd != -1)
close(fd);
if (fd1 != -1)