ChattyLogBuffer ignores the metadata (timestamp, pid, std::list<>
iterators, etc) of log entries when calculating the size used by a
given log buffer. For example, if 1MB is the specified size of the
'main' log buffer, logd will use between ~1.3MB and ~2MB of overall
memory for 'main' log buffer. LogStatistics does track the overall
memory used and labels it 'Overhead', however this 'Overhead' is only
informative and is not used for Pruning or Chatty calculations.
This is problematic, since it makes logd's memory usage inconsistent:
depending on the pattern of logging, there can be substantially more
memory used than the specified log buffer size. This is further
complicated by the fact that chatty messages are entirely metadata and
therefore not counted as contributing to the log buffer size.
This change would switch logd to always track the full size of log
buffers, but there are two problems with this approach:
1) Unless users double their buffer sizes, then they'd have
substantially fewer logs after the change
2) Chatty logic would change and it's difficult to evaluate.
Therefore this change only provides the framework to track the full
size of log buffers. This allows an apples to apples comparison of
ChattyLogBuffer and SerializedLogBuffer. With this option enabled,
logd reports the following values:
ChattyLogBuffer:
Total log size (logcat -g), 'Total' / 'Now' (logcat -S), and
'Overhead' (logcat -S) all report the full size of log entries
including metadata.
SerializedLogBuffer:
Total log size (logcat -g) and 'Overhead' (logcat -S) report the
compressed size of the log entries including metadata.
'Total' / 'Now' (logcat -S) reports the uncompressed size of the log
entries that are available including metadata.
Test: logging statistics are correct
Change-Id: If17682af8bb605f31387d7b210b69a301dd48f07
f74503dd46