unpack-objects: use the bulk-checkin infrastructure

The unpack-objects functionality is used by fetch, push, and fast-import
to turn the transfered data into object database entries when there are
fewer objects than the 'unpacklimit' setting.

By enabling an odb-transaction when unpacking objects, we can take advantage
of batched fsyncs.

Here are some performance numbers to justify batch mode for
unpack-objects, collected on a WSL2 Ubuntu VM.

Fsync Mode | Time for 90 objects (ms)
-------------------------------------
       Off | 170
  On,fsync | 760
  On,batch | 230

Note that the default unpackLimit is 100 objects, so there's a 3x
benefit in the worst case. The non-batch mode fsync scales linearly
with the number of objects, so there are significant benefits even with
smaller numbers of objects.

Signed-off-by: Neeraj Singh <neerajsi@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Neeraj Singh 2022-04-04 22:20:13 -07:00 committed by Junio C Hamano
parent 23a3a303ab
commit 425d290ce5

View file

@ -1,5 +1,6 @@
#include "builtin.h"
#include "cache.h"
#include "bulk-checkin.h"
#include "config.h"
#include "object-store.h"
#include "object.h"
@ -503,10 +504,12 @@ static void unpack_all(void)
if (!quiet)
progress = start_progress(_("Unpacking objects"), nr_objects);
CALLOC_ARRAY(obj_list, nr_objects);
begin_odb_transaction();
for (i = 0; i < nr_objects; i++) {
unpack_one(i);
display_progress(progress, i + 1);
}
end_odb_transaction();
stop_progress(&progress);
if (delta_list)