logcat 设置缓存区 设置buff

logcat 的buff 有2种分配方式，一种是在kernel的，一种是logd， MM用的是在logd的这种的

system/core/liblog/Android.mk

ifneq ($(TARGET_USES_LOGD),false)
liblog_sources := logd_write.c log_event_write.c
else
liblog_sources := logd_write_kern.c
endif

修改logcat的buff有可以从开发者选项中设置，
也可以从logcat -G 10M 设置


root@xx:/ # logcat -g
main: ring buffer is 4Mb (839Kb consumed), max entry is 5120b, max payload is 4076b
system: ring buffer is 4Mb (2Mb consumed), max entry is 5120b, max payload is 4076b
crash: ring buffer is 4Mb (0b consumed), max entry is 5120b, max payload is 4076b
root@xx:/ # logcat -G 11M
root@xx:/ # logcat -g                                                      
main: ring buffer is 11Mb (854Kb consumed), max entry is 5120b, max payload is 4076b
system: ring buffer is 11Mb (2Mb consumed), max entry is 5120b, max payload is 4076b
crash: ring buffer is 11Mb (0b consumed), max entry is 5120b, max payload is 4076b
root@xx:/ #