perf lock: Fix state machine to recognize lock sequence
Previous state machine of perf lock was really broken.
This patch improves it a little.
This patch prepares the list of state machine that represents
lock sequences for each threads.
These state machines can be one of these sequences:
1) acquire -> acquired -> release
2) acquire -> contended -> acquired -> release
3) acquire (w/ try) -> release
4) acquire (w/ read) -> release
The case of 4) is a little special.
Double acquire of read lock is allowed, so the state machine
counts read lock number, and permits double acquire and release.
But, things are not so simple. Something in my model is still wrong.
I counted the number of lock instances with bad sequence,
and ratio is like this (case of tracing whoami): bad:233, total:2279
version 2:
* threads are now identified with tid, not pid
* prepared SEQ_STATE_READ_ACQUIRED for read lock.
* bunch of struct lock_seq_stat is now linked list
* debug information enhanced (this have to be removed someday)
e.g.
| === output for debug===
|
| bad:233, total:2279
| bad rate:0.000000
| histogram of events caused bad sequence
| acquire: 165
| acquired: 0
| contended: 0
| release: 68
Signed-off-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <1271852634-9351-1-git-send-email-mitake@dcl.info.waseda.ac.jp>
[rename SEQ_STATE_UNINITED to SEQ_STATE_UNINITIALIZED]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
1 file changed