2 Commits

Author	SHA1	Message	Date
Chris Mason	35d8ba6629	Btrfs: Worker thread optimizations ... This changes the worker thread pool to maintain a list of idle threads, avoiding a complex search for a good thread to wake up. Threads have two states: idle - we try to reuse the last thread used in hopes of improving the batching ratios busy - each time a new work item is added to a busy task, the task is rotated to the end of the line. Signed-off-by: Chris Mason <chris.mason@oracle.com>	2008-09-25 11:04:03 -04:00
Chris Mason	8b71284292	Btrfs: Add async worker threads for pre and post IO checksumming ... Btrfs has been using workqueues to spread the checksumming load across other CPUs in the system. But, workqueues only schedule work on the same CPU that queued the work, giving them a limited benefit for systems with higher CPU counts. This code adds a generic facility to schedule work with pools of kthreads, and changes the bio submission code to queue bios up. The queueing is important to make sure large numbers of procs on the system don't turn streaming workloads into random workloads by sending IO down concurrently. The end result of all of this is much higher performance (and CPU usage) when doing checksumming on large machines. Two worker pools are created, one for writes and one for endio processing. The two could deadlock if we tried to service both from a single pool. Signed-off-by: Chris Mason <chris.mason@oracle.com>	2008-09-25 11:04:03 -04:00