How do I increase the log size of dev/log/main?

Question

How do I increase the size of dev/log/main by a factor of 10? My understanding is the log has a fixed size (16K?) and rolls over when that limit is reached. I'd like to find out what the log size is currently set at and increase it by a lot.

I'm debugging an issue that occurs infrequently when the device hasn't been used for a long period of time (maybe an hour?). I've instrumented the code with log messages so I can understand what is happening when the bug occurs.

My problem is my instrumentation causes the log to roll over in about 2 minutes. I would like to increase the size of dev/log/main by a factor of 10 if possible.

Answer 1

To find out the actual size of the ring buffer, you can use

$ adb logcat -g

To adjust the size of the ring buffer, you might try

$ adb logcat -r <kbytes>

At least that's what some tutorials say. For more details, you might want to read "adb logcat" Command Options and Log Buffers.

P.S.: I guess those settings (manual adjusted ring buffer size) will not survive a reboot -- just to consider.

Answer 2

If you're looking to change the default size for a log buffer, to persist between reboots, you can recompile the kernel with updated buffer sizes.

The file containing log buffer definitions is:

<kernel>/drivers/staging/android/logger.c

The versions I'm looking at use a macro to define log buffers in that file:

DEFINE_LOGGER_DEVICE(variable, name, size)

There will likely be a number of loggers; "main" is usually the one you're looking for.