Merge "Adjust the size limit for splitting large files"
diff --git a/tools/releasetools/blockimgdiff.py b/tools/releasetools/blockimgdiff.py
index 1a5b93d..cef0c6f 100644
--- a/tools/releasetools/blockimgdiff.py
+++ b/tools/releasetools/blockimgdiff.py
@@ -987,29 +987,36 @@
too many blocks (greater than MAX_BLOCKS_PER_DIFF_TRANSFER), we split it
into smaller pieces by getting multiple Transfer()s.
- The downside is that after splitting, we can no longer use imgdiff but
- only bsdiff."""
-
- MAX_BLOCKS_PER_DIFF_TRANSFER = 1024
+ The downside is that after splitting, we may increase the package size
+ since the split pieces don't align well. According to our experiments,
+ 1/8 of the cache size as the per-piece limit appears to be optimal.
+ Compared to the fixed 1024-block limit, it reduces the overall package
+ size by 30% volantis, and 20% for angler and bullhead."""
# We care about diff transfers only.
if style != "diff" or not split:
Transfer(tgt_name, src_name, tgt_ranges, src_ranges, style, by_id)
return
+ pieces = 0
+ cache_size = common.OPTIONS.cache_size
+ split_threshold = 0.125
+ max_blocks_per_transfer = int(cache_size * split_threshold /
+ self.tgt.blocksize)
+
# Change nothing for small files.
- if (tgt_ranges.size() <= MAX_BLOCKS_PER_DIFF_TRANSFER and
- src_ranges.size() <= MAX_BLOCKS_PER_DIFF_TRANSFER):
+ if (tgt_ranges.size() <= max_blocks_per_transfer and
+ src_ranges.size() <= max_blocks_per_transfer):
Transfer(tgt_name, src_name, tgt_ranges, src_ranges, style, by_id)
return
- pieces = 0
- while (tgt_ranges.size() > MAX_BLOCKS_PER_DIFF_TRANSFER and
- src_ranges.size() > MAX_BLOCKS_PER_DIFF_TRANSFER):
+ while (tgt_ranges.size() > max_blocks_per_transfer and
+ src_ranges.size() > max_blocks_per_transfer):
tgt_split_name = "%s-%d" % (tgt_name, pieces)
src_split_name = "%s-%d" % (src_name, pieces)
- tgt_first = tgt_ranges.first(MAX_BLOCKS_PER_DIFF_TRANSFER)
- src_first = src_ranges.first(MAX_BLOCKS_PER_DIFF_TRANSFER)
+ tgt_first = tgt_ranges.first(max_blocks_per_transfer)
+ src_first = src_ranges.first(max_blocks_per_transfer)
+
Transfer(tgt_split_name, src_split_name, tgt_first, src_first, style,
by_id)
