Choose the copy buffer size used for reading files

to be archived dynamically:
  * At least 64k
  * At least as large as the -b setting
In particular, this should speed up things noticably when large -b
values are in use.  This is also the first cut at aligning the copy
buffer so we can take advantage of O_DIRECT someday.

SVN-Revision: 2504

diff --git a/tar/bsdtar.h b/tar/bsdtar.h
index 35bacd70a6d4b69924bd910cf18d8f15deb8017f..84dfc9500dbaad389ebb72f9ed96e9d8b68c140b 100644 (file)
--- a/tar/bsdtar.h
+++ b/tar/bsdtar.h
@@ -103,6 +103,7 @@ struct bsdtar {
        struct archive_dir      *archive_dir;   /* for write.c */
        struct name_cache       *gname_cache;   /* for write.c */
        char                    *buff;          /* for write.c */
+       size_t                   buff_size;     /* for write.c */
        struct lafe_matching    *matching;      /* for matching.c */
        struct security         *security;      /* for read.c */
        struct name_cache       *uname_cache;   /* for write.c */

diff --git a/tar/write.c b/tar/write.c
index aedb0c1646b2f25ce612b7510133eac190b9e52b..e65081a231290b855e7739e98891eef9b45d2276 100644 (file)
--- a/tar/write.c
+++ b/tar/write.c
@@ -98,9 +98,6 @@ __FBSDID("$FreeBSD: src/usr.bin/tar/write.c,v 1.79 2008/11/27 05:49:52 kientzle
 #include "line_reader.h"
 #include "tree.h"
 
-/* Size of buffer for holding file data prior to writing. */
-#define        FILEDATABUFLEN  65536
-
 /* Fixed size of uname/gname caches. */
 #define        name_cache_size 101
 
@@ -152,7 +149,7 @@ static void          write_entry(struct bsdtar *, struct archive *,
 static void             write_file(struct bsdtar *, struct archive *,
                             struct archive_entry *);
 static int              write_file_data(struct bsdtar *, struct archive *,
-                            struct archive_entry *, int fd);
+                            struct archive_entry *, int fd, size_t align);
 static void             write_hierarchy(struct bsdtar *, struct archive *,
                             const char *);
 
@@ -438,8 +435,15 @@ write_archive(struct archive *a, struct bsdtar *bsdtar)
        const char *arg;
        struct archive_entry *entry, *sparse_entry;
 
+       /* Choose a suitable copy buffer size */
+       bsdtar->buff_size = 64 * 1024;
+       while (bsdtar->buff_size < bsdtar->bytes_per_block)
+         bsdtar->buff_size *= 2;
+       /* Try to compensate for space we'll lose to alignment. */
+       bsdtar->buff_size += 16 * 1024;
+
        /* Allocate a buffer for file data. */
-       if ((bsdtar->buff = malloc(FILEDATABUFLEN)) == NULL)
+       if ((bsdtar->buff = malloc(bsdtar->buff_size)) == NULL)
                lafe_errc(1, 0, "cannot allocate memory");
 
        if ((bsdtar->resolver = archive_entry_linkresolver_new()) == NULL)
@@ -641,7 +645,7 @@ copy_file_data(struct bsdtar *bsdtar, struct archive *a,
        ssize_t bytes_written;
        int64_t progress = 0;
 
-       bytes_read = archive_read_data(ina, bsdtar->buff, FILEDATABUFLEN);
+       bytes_read = archive_read_data(ina, bsdtar->buff, bsdtar->buff_size);
        while (bytes_read > 0) {
                if (need_report())
                        report_write(bsdtar, a, entry, progress);
@@ -653,8 +657,7 @@ copy_file_data(struct bsdtar *bsdtar, struct archive *a,
                        return (-1);
                }
                progress += bytes_written;
-               bytes_read = archive_read_data(ina, bsdtar->buff,
-                   FILEDATABUFLEN);
+               bytes_read = archive_read_data(ina, bsdtar->buff, bsdtar->buff_size);
        }
 
        return (0);
@@ -1028,10 +1031,17 @@ write_entry(struct bsdtar *bsdtar, struct archive *a,
 {
        int fd = -1;
        int e;
+       size_t align = 4096;
 
        if (archive_entry_size(entry) > 0) {
                const char *pathname = archive_entry_sourcepath(entry);
+               /* TODO: Use O_DIRECT here and set 'align' to the
+                * actual filesystem block size.  As of July 2010, new
+                * directory-traversal code is going in that will make
+                * it much easier to track filesystem properties like
+                * this during the traversal. */
                fd = open(pathname, O_RDONLY | O_BINARY);
+               align = 4096;
                if (fd == -1) {
                        if (!bsdtar->verbose)
                                lafe_warnc(errno,
@@ -1062,7 +1072,7 @@ write_entry(struct bsdtar *bsdtar, struct archive *a,
         * that case, just skip the write.
         */
        if (e >= ARCHIVE_WARN && fd >= 0 && archive_entry_size(entry) > 0) {
-               if (write_file_data(bsdtar, a, entry, fd))
+               if (write_file_data(bsdtar, a, entry, fd, align))
                        exit(1);
        }
 
@@ -1106,19 +1116,26 @@ report_write(struct bsdtar *bsdtar, struct archive *a,
 /* Helper function to copy file to archive. */
 static int
 write_file_data(struct bsdtar *bsdtar, struct archive *a,
-    struct archive_entry *entry, int fd)
+    struct archive_entry *entry, int fd, size_t align)
 {
        ssize_t bytes_read;
        ssize_t bytes_written;
        int64_t progress = 0;
-
-       bytes_read = read(fd, bsdtar->buff, FILEDATABUFLEN);
+       size_t  buff_size;
+       char   *buff = bsdtar->buff;
+
+       /* Round 'buff' up to the next multiple of 'align' and reduce
+        * 'buff_size' accordingly. */
+       buff = (char *)((((uintptr_t)buff + align - 1) / align) * align);
+       buff_size = bsdtar->buff + bsdtar->buff_size - buff;
+       buff_size = (buff_size / align) * align;
+       
+       bytes_read = read(fd, buff, buff_size);
        while (bytes_read > 0) {
                if (need_report())
                        report_write(bsdtar, a, entry, progress);
 
-               bytes_written = archive_write_data(a, bsdtar->buff,
-                   bytes_read);
+               bytes_written = archive_write_data(a, buff, bytes_read);
                if (bytes_written < 0) {
                        /* Write failed; this is bad */
                        lafe_warnc(0, "%s", archive_error_string(a));
@@ -1132,7 +1149,7 @@ write_file_data(struct bsdtar *bsdtar, struct archive *a,
                        return (0);
                }
                progress += bytes_written;
-               bytes_read = read(fd, bsdtar->buff, FILEDATABUFLEN);
+               bytes_read = read(fd, buff, buff_size);
        }
        return 0;
 }