Break metadata into smaller chunks (number of chunks=10) for faster delta generation.
Here are some data for comparison.
Without any metadata processing:
Run Time:
real 2m22.331s
user 1m56.040s
sys 0m6.170s
Payload Size:
756162 bytes
With metadata processing (number of chunks=4):
Run Time:
real 13m48.292s
user 13m10.120s
sys 0m6.920s
Payload Size:
749713 bytes
With metadata processing (number of chunks=10):
Run Time:
real 3m46.242s
user 3m17.880s
sys 0m6.640s
Payload Size:
748464 bytes
BUG=chromium-os:10669
TEST=Unit tests and generated delta payloads between two images that do
not have their metadata preserved. Ran the delta generator with and
without metadata processing and also used different number of chunks for
comparison purposes.
Change-Id: I15ff831b95f43cbebbcca6ecc6a3fbc404b6f065
Review URL: http://codereview.chromium.org/6060012
diff --git a/metadata.cc b/metadata.cc
index 20c0a0d..7dfc787 100644
--- a/metadata.cc
+++ b/metadata.cc
@@ -220,7 +220,7 @@
// Due to bsdiff slowness, we're going to break each block group down
// into metadata chunks and feed them to bsdiff.
- __u32 num_chunks = 4;
+ __u32 num_chunks = 10;
__u32 blocks_per_chunk = num_metadata_blocks / num_chunks;
__u32 curr_block = bg_start_block;
for (__u32 chunk = 0; chunk < num_chunks; chunk++) {