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
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btrfs	Btrfs: Add async worker threads for pre and post IO checksumming	2008-09-25 11:04:03 -04:00