linux/include/trace/events/writeback.h, branch v2.6.36

writeback: add new tracepoints

2010-08-07T16:53:56Z

Add 2 new trace points to the periodic write-back wake up case, just like we do in the 'bdi_queue_work()' function. Namely, introduce: 1. trace_writeback_wake_thread(bdi) 2. trace_writeback_wake_forker_thread(bdi) The first event is triggered every time we wake up a bdi thread to start periodic background write-out. The second event is triggered only when the bdi thread does not exist and should be created by the forker thread. This patch was suggested by Dave Chinner and Christoph Hellwig. Signed-off-by: Artem Bityutskiy Signed-off-by: Jens Axboe

writeback.h: needs linux/device.h

2010-08-07T16:26:35Z

include/trace/events/writeback.h uses dev_name(), so it needs to include linux/device.h. include/trace/events/writeback.h:12: error: implicit declaration of function 'dev_name' Signed-off-by: Randy Dunlap Signed-off-by: Jens Axboe

writeback: Add tracing to write_cache_pages

2010-08-07T16:24:26Z

Add a trace event to the ->writepage loop in write_cache_pages to give visibility into how the ->writepage call is changing variables within the writeback control structure. Of most interest is how wbc->nr_to_write changes from call to call, especially with filesystems that write multiple pages in ->writepage. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe

writeback: Add tracing to balance_dirty_pages

2010-08-07T16:24:25Z

Tracing high level background writeback events is good, but it doesn't give the entire picture. Add visibility into write throttling to catch IO dispatched by foreground throttling of processing dirtying lots of pages. Signed-off-by: Dave Chinner Signed-off-by: Jens Axboe

writeback: Initial tracing support

2010-08-07T16:24:23Z

Trace queue/sched/exec parts of the writeback loop. This provides insight into when and why flusher threads are scheduled to run. e.g a sync invocation leaves traces like: sync-[...]: writeback_queue: bdi 8:0: sb_dev 8:1 nr_pages=7712 sync_mode=0 kupdate=0 range_cyclic=0 background=0 flush-8:0-[...]: writeback_exec: bdi 8:0: sb_dev 8:1 nr_pages=7712 sync_mode=0 kupdate=0 range_cyclic=0 background=0 This also lays the foundation for adding more writeback tracing to provide deeper insight into the whole writeback path. The original tracing code is from Jens Axboe, though this version is a rewrite as a result of the code being traced changing significantly. Signed-off-by: Dave Chinner Signed-off-by: Jens Axboe