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Let user choose larger buffers for IO reading 

Simultaneous reading of multiple files through a small one-page buffer
is slow with classic HDDs. Let the user improve it by chosing buffers of
several mebibytes if needed.

[kzak@redhat.com: - tiny changes to coding style
                  - mark buffers static
                  - use xalloc.h]

Signed-off-by: Eduard Bloch <blade@debian.org>
Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Eduard Bloch 2021-09-27 09:07:23 +02:00 committed by Karel Zak
parent 0647bbe519
commit 722762b617
2 changed files with 45 additions and 6 deletions
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6
misc-utils/hardlink.1.adoc
View File

@ -71,6 +71,12 @@ A regular expression to include files. If the option *--exclude* has been given,
*-s*, *--minimum-size* _size_::
The minimum size to consider. By default this is 1, so empty files will not be linked. The _size_ argument may be followed by the multiplicative suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has the same meaning as "KiB").
*-S*, *--buffer-size* _size_::
The size of read buffer used when comparing file contents (default: 8KiB). This
costs some additional memory but potentially reduces the amount of seek
operations and therefore improve performance, especially with mechanic disk
drives. Optional factor suffixes are supported, like with the *-s* option. This is mostly efficient with other filters (i.e. with *-f* or *-X*) and can be less efficient with *-top* options.
== ARGUMENTS
*hardlink* takes one or more directories which will be searched for files to be linked.

45
misc-utils/hardlink.c
View File

@ -91,6 +91,10 @@ enum log_level {
JLOG_VERBOSE2
};
#ifndef DEF_SCAN_BUFSIZ
# define DEF_SCAN_BUFSIZ 8192
#endif
/**
* struct statistic - Statistics about the file
* @started: Whether we are post command-line processing
@ -149,6 +153,7 @@ static struct options {
unsigned int keep_oldest:1;
unsigned int dry_run:1;
uintmax_t min_size;
size_t bufsiz;
} opts = {
/* default setting */
.respect_mode = TRUE,
@ -156,7 +161,8 @@ static struct options {
.respect_time = TRUE,
.respect_xattrs = FALSE,
.keep_oldest = FALSE,
.min_size = 1
.min_size = 1,
.bufsiz = DEF_SCAN_BUFSIZ
};
/*
@ -168,6 +174,12 @@ static struct options {
static void *files;
static void *files_by_ino;
/*
* Temporary buffers for reading file contents
*/
static char *buf_a = NULL;
static char *buf_b = NULL;
/*
* last_signal
*
@ -552,8 +564,6 @@ static int file_contents_equal(const struct file *a, const struct file *b)
{
FILE *fa = NULL;
FILE *fb = NULL;
char buf_a[8192];
char buf_b[8192];
int cmp = 0; /* zero => equal */
off_t off = 0; /* current offset */
@ -579,11 +589,11 @@ static int file_contents_equal(const struct file *a, const struct file *b)
size_t ca;
size_t cb;
ca = fread(buf_a, 1, sizeof(buf_a), fa);
ca = fread(buf_a, 1, opts.bufsiz, fa);
if (ca < sizeof(buf_a) && ferror(fa))
goto err;
cb = fread(buf_b, 1, sizeof(buf_b), fb);
cb = fread(buf_b, 1, opts.bufsiz, fb);
if (cb < sizeof(buf_b) && ferror(fb))
goto err;
@ -919,6 +929,7 @@ static void __attribute__((__noreturn__)) usage(void)
fputs(_(" -x, --exclude <regex> regular expression to exclude files\n"), out);
fputs(_(" -i, --include <regex> regular expression to include files/dirs\n"), out);
fputs(_(" -s, --minimum-size <size> minimum size for files.\n"), out);
fputs(_(" -S, --buffer-size <size> buffer size for file reading (speedup, using more RAM)\n"), out);
fputs(_(" -c, --content compare only file contents, same as -pot\n"), out);
fputs(USAGE_SEPARATOR, out);
@ -929,6 +940,18 @@ static void __attribute__((__noreturn__)) usage(void)
}
static void init_buffers(size_t bufsiz)
{
buf_a = xmalloc(bufsiz);
buf_b = xmalloc(bufsiz);
}
static void deinit_buffers(void)
{
free(buf_a);
free(buf_b);
}
/**
* parse_options - Parse the command line options
* @argc: Number of options
@ -936,7 +959,7 @@ static void __attribute__((__noreturn__)) usage(void)
*/
static int parse_options(int argc, char *argv[])
{
static const char optstr[] = "VhvnfpotXcmMOx:i:s:q";
static const char optstr[] = "VhvnfpotXcmMOx:i:s:S:q";
static const struct option long_options[] = {
{"version", no_argument, NULL, 'V'},
{"help", no_argument, NULL, 'h'},
@ -953,6 +976,7 @@ static int parse_options(int argc, char *argv[])
{"exclude", required_argument, NULL, 'x'},
{"include", required_argument, NULL, 'i'},
{"minimum-size", required_argument, NULL, 's'},
{"buffer-size", required_argument, NULL, 'S'},
{"content", no_argument, NULL, 'c'},
{"quiet", no_argument, NULL, 'q'},
{NULL, 0, NULL, 0}
@ -1018,6 +1042,9 @@ static int parse_options(int argc, char *argv[])
case 's':
opts.min_size = strtosize_or_err(optarg, _("failed to parse size"));
break;
case 'S':
opts.bufsiz = strtosize_or_err(optarg, _("failed to parse size"));
break;
case 'h':
usage();
case 'V':
@ -1074,6 +1101,9 @@ int main(int argc, char *argv[])
errx(EXIT_FAILURE, _("no directory or file specified"));
gettime_monotonic(&stats.start_time);
init_buffers(opts.bufsiz);
stats.started = TRUE;
for (; optind < argc; optind++) {
@ -1082,5 +1112,8 @@ int main(int argc, char *argv[])
}
twalk(files, visitor);
deinit_buffers();
return 0;
}