From: Eduard Bloch <blade@xxxxxxxxxx>
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.
Signed-off-by: Eduard Bloch <blade@xxxxxxxxxx>
---
misc-utils/hardlink.1.adoc | 6 +++++
misc-utils/hardlink.c | 50 ++++++++++++++++++++++++++++++++------
2 files changed, 49 insertions(+), 7 deletions(-)
diff --git a/misc-utils/hardlink.1.adoc b/misc-utils/hardlink.1.adoc
index 1fab77d71..107cd6997 100644
--- a/misc-utils/hardlink.1.adoc
+++ b/misc-utils/hardlink.1.adoc
@@ -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.
diff --git a/misc-utils/hardlink.c b/misc-utils/hardlink.c
index 29c8509e3..aeb486ce5 100644
--- a/misc-utils/hardlink.c
+++ b/misc-utils/hardlink.c
@@ -91,6 +91,10 @@ enum log_level {
JLOG_VERBOSE2
};
+#ifndef DEF_SCAN_BUF_SIZE
+#define DEF_SCAN_BUF_SIZE 8192
+#endif
+
/**
* struct statistic - Statistics about the file
* @started: Whether we are post command-line processing
@@ -144,6 +148,7 @@ static struct options {
unsigned int keep_oldest:1;
unsigned int dry_run:1;
uintmax_t min_size;
+ size_t buf_size;
} opts = {
/* default setting */
.respect_mode = TRUE,
@@ -151,7 +156,8 @@ static struct options {
.respect_time = TRUE,
.respect_xattrs = FALSE,
.keep_oldest = FALSE,
- .min_size = 1
+ .min_size = 1,
+ .buf_size = DEF_SCAN_BUF_SIZE
};
/*
@@ -163,6 +169,12 @@ static struct options {
static void *files;
static void *files_by_ino;
+/*
+ * Temporary buffers for reading file contents
+ */
+char *buf_a = NULL;
+char *buf_b = NULL;
+
/*
* last_signal
*
@@ -523,8 +535,6 @@ 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 */
@@ -550,11 +560,11 @@ 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.buf_size, 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.buf_size, fb);
if (cb < sizeof(buf_b) && ferror(fb))
goto err;
@@ -889,7 +899,8 @@ static void __attribute__((__noreturn__)) usage(void)
" (lower precedence than minimize/maximize)\n"), out);
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, --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);
@@ -923,6 +934,20 @@ static void register_regex(struct regex_link **pregs, const char *regex)
link->next = *pregs; *pregs = link;
}
+static int init_buffers(size_t bufsize)
+{
+ buf_a = malloc(bufsize);
+ buf_b = malloc(bufsize);
+ // report non-zero if any failed
+ return (NULL == buf_a || NULL == buf_b);
+}
+
+static void deinit_buffers(void)
+{
+ free(buf_a);
+ free(buf_b);
+}
+
/**
* parse_options - Parse the command line options
* @argc: Number of options
@@ -930,7 +955,7 @@ static void register_regex(struct regex_link **pregs, const char *regex)
*/
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'},
@@ -947,6 +972,7 @@ 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}
@@ -1012,6 +1038,9 @@ 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.buf_size = strtosize_or_err(optarg, _("failed to parse size"));
+ break;
case 'h':
usage();
case 'V':
@@ -1068,6 +1097,10 @@ int main(int argc, char *argv[])
errx(EXIT_FAILURE, _("no directory or file specified"));
gettime_monotonic(&stats.start_time);
+
+ if (init_buffers(opts.buf_size) != 0)
+ err(EXIT_FAILURE, _("failed to allocate buffer memory"));
+
stats.started = TRUE;
for (; optind < argc; optind++) {
@@ -1076,5 +1109,8 @@ int main(int argc, char *argv[])
}
twalk(files, visitor);
+
+ deinit_buffers();
+
return 0;
}
--
2.33.0
