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journal: sort data items of entries by offset 

This should slightly optimize disk access patterns on rotating disks for
simple readers.
This commit is contained in:
Lennart Poettering 2012-10-16 21:40:48 +02:00
parent b87705cdd2
commit 1f2da9ec51
1 changed files with 14 additions and 0 deletions
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14
src/journal/journal-file.c
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@ -1053,6 +1053,16 @@ void journal_file_post_change(JournalFile *f) {
log_error("Failed to truncate file to its own size: %m");
}
static int entry_item_cmp(const void *_a, const void *_b) {
const EntryItem *a = _a, *b = _b;
if (le64toh(a->object_offset) < le64toh(b->object_offset))
return -1;
if (le64toh(a->object_offset) > le64toh(b->object_offset))
return 1;
return 0;
}
int journal_file_append_entry(JournalFile *f, const dual_timestamp *ts, const struct iovec iovec[], unsigned n_iovec, uint64_t *seqnum, Object **ret, uint64_t *offset) {
unsigned i;
EntryItem *items;
@ -1097,6 +1107,10 @@ int journal_file_append_entry(JournalFile *f, const dual_timestamp *ts, const st
items[i].hash = o->data.hash;
}
/* Order by the position on disk, in order to improve seek
* times for rotating media. */
qsort(items, n_iovec, sizeof(EntryItem), entry_item_cmp);
r = journal_file_append_entry_internal(f, ts, xor_hash, items, n_iovec, seqnum, ret, offset);
journal_file_post_change(f);