From bb86e1d9c298940a11da0a3d47ed40f7b709194d Mon Sep 17 00:00:00 2001 From: Tianjie Xu Date: Wed, 13 Jan 2016 16:14:10 -0800 Subject: [PATCH] Adjust the size limit for splitting large files Modify the number of max blocks per transfer to reduce splitting of large files during patch generation. This will reduce the size of final incremental OTA updater package. In specific, the size limit for each file to transfer is set to 1/8 cachesize instead of a fix number. Bug: 26472126 Change-Id: Iffb135e378c4c7a91640f2fc4c40e9e93d1fe4bb --- tools/releasetools/blockimgdiff.py | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) diff --git a/tools/releasetools/blockimgdiff.py b/tools/releasetools/blockimgdiff.py index 1a5b93d32..cef0c6ff4 100644 --- a/tools/releasetools/blockimgdiff.py +++ b/tools/releasetools/blockimgdiff.py @@ -987,29 +987,36 @@ class BlockImageDiff(object): 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) -- 2.11.0