atrace: don't use sendfile.
sendfile appears to have horrendous performance when used with the
ftrace output file, being up to 100x slower than the naive read/write
loop.
Switch to doing that instead, speeding up atrace from:
$ atrace --async_start sched freq; sleep 1; time atrace --async_stop > dummy
c apturing trace... 0m08.93s real 0m00.08s user 0m07.98s system
to:
$ atrace --async_start sched freq; sleep 1; time atrace --async_stop > dummy
capturing trace... 0m00.78s real 0m00.07s user 0m00.21s system
Bug: http://b/37164190
Test: atrace --async_start sched freq; sleep 1; time atrace --async_stop > dummy
Change-Id: I22fe1871e263867f9ac54c8f5b474df824b4bc69
1 file changed