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fsck: drop inode-sorting code

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Fsck tries to access loose objects in order of inode number,
with the hope that this would make cold cache access faster
on a spinning disk. This dates back to 7e8c174 (fsck-cache:
sort entries by inode number, 2005-05-02), which predates
the invention of packfiles.

These days, there's not much point in trying to optimize
cold cache for a large number of loose objects. You are much
better off to simply pack the objects, which will reduce the
disk footprint _and_ provide better locality of data access.

So while you can certainly construct pathological cases
where this code might help, it is not worth the trouble
anymore.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff King 2015-09-24 17:08:28 -04:00 committed by Junio C Hamano
parent eddda37144
commit 144e4cf709
1 changed files with 2 additions and 68 deletions
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70
builtin/fsck.c
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@ -39,14 +39,6 @@ static int show_dangling = 1;
#define ERROR_REACHABLE 02
#define ERROR_PACK 04
#ifdef NO_D_INO_IN_DIRENT
#define SORT_DIRENT 0
#define DIRENT_SORT_HINT(de) 0
#else
#define SORT_DIRENT 1
#define DIRENT_SORT_HINT(de) ((de)->d_ino)
#endif
static int fsck_config(const char *var, const char *value, void *cb)
{
if (strcmp(var, "fsck.skiplist") == 0) {
@ -373,64 +365,6 @@ static int fsck_obj_buffer(const unsigned char *sha1, enum object_type type,
return fsck_obj(obj);
}
/*
* This is the sorting chunk size: make it reasonably
* big so that we can sort well..
*/
#define MAX_SHA1_ENTRIES (1024)
struct sha1_entry {
unsigned long ino;
unsigned char sha1[20];
};
static struct {
unsigned long nr;
struct sha1_entry *entry[MAX_SHA1_ENTRIES];
} sha1_list;
static int ino_compare(const void *_a, const void *_b)
{
const struct sha1_entry *a = _a, *b = _b;
unsigned long ino1 = a->ino, ino2 = b->ino;
return ino1 < ino2 ? -1 : ino1 > ino2 ? 1 : 0;
}
static void fsck_sha1_list(void)
{
int i, nr = sha1_list.nr;
if (SORT_DIRENT)
qsort(sha1_list.entry, nr,
sizeof(struct sha1_entry *), ino_compare);
for (i = 0; i < nr; i++) {
struct sha1_entry *entry = sha1_list.entry[i];
unsigned char *sha1 = entry->sha1;
sha1_list.entry[i] = NULL;
if (fsck_sha1(sha1))
errors_found |= ERROR_OBJECT;
free(entry);
}
sha1_list.nr = 0;
}
static void add_sha1_list(unsigned char *sha1, unsigned long ino)
{
struct sha1_entry *entry = xmalloc(sizeof(*entry));
int nr;
entry->ino = ino;
hashcpy(entry->sha1, sha1);
nr = sha1_list.nr;
if (nr == MAX_SHA1_ENTRIES) {
fsck_sha1_list();
nr = 0;
}
sha1_list.entry[nr] = entry;
sha1_list.nr = ++nr;
}
static inline int is_loose_object_file(struct dirent *de,
char *name, unsigned char *sha1)
{
@ -459,7 +393,8 @@ static void fsck_dir(int i, char *path)
if (is_dot_or_dotdot(de->d_name))
continue;
if (is_loose_object_file(de, name, sha1)) {
add_sha1_list(sha1, DIRENT_SORT_HINT(de));
if (fsck_sha1(sha1))
errors_found |= ERROR_OBJECT;
continue;
}
if (starts_with(de->d_name, "tmp_obj_"))
@ -573,7 +508,6 @@ static void fsck_object_dir(const char *path)
display_progress(progress, i+1);
}
stop_progress(&progress);
fsck_sha1_list();
}
static int fsck_head_link(void)