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* [XFS] Move AIL pushing into it's own threadDavid Chinner2008-02-071-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When many hundreds to thousands of threads all try to do simultaneous transactions and the log is in a tail-pushing situation (i.e. full), we can get multiple threads walking the AIL list and contending on the AIL lock. The AIL push is, in effect, a simple I/O dispatch algorithm complicated by the ordering constraints placed on it by the transaction subsystem. It really does not need multiple threads to push on it - even when only a single CPU is pushing the AIL, it can push the I/O out far faster that pretty much any disk subsystem can handle. So, to avoid contention problems stemming from multiple list walkers, move the list walk off into another thread and simply provide a "target" to push to. When a thread requires a push, it sets the target and wakes the push thread, then goes to sleep waiting for the required amount of space to become available in the log. This mechanism should also be a lot fairer under heavy load as the waiters will queue in arrival order, rather than queuing in "who completed a push first" order. Also, by moving the pushing to a separate thread we can do more effectively overload detection and prevention as we can keep context from loop iteration to loop iteration. That is, we can push only part of the list each loop and not have to loop back to the start of the list every time we run. This should also help by reducing the number of items we try to lock and/or push items that we cannot move. Note that this patch is not intended to solve the inefficiencies in the AIL structure and the associated issues with extremely large list contents. That needs to be addresses separately; parallel access would cause problems to any new structure as well, so I'm only aiming to isolate the structure from unbounded parallelism here. SGI-PV: 972759 SGI-Modid: xfs-linux-melb:xfs-kern:30371a Signed-off-by: David Chinner <dgc@sgi.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
* [XFS] Unwrap AIL_LOCKDonald Douwsma2008-02-071-3/+2
| | | | | | | | | SGI-PV: 970382 SGI-Modid: xfs-linux-melb:xfs-kern:29739a Signed-off-by: Donald Douwsma <donaldd@sgi.com> Signed-off-by: Eric Sandeen <sandeen@sandeen.net> Signed-off-by: Tim Shimmin <tes@sgi.com>
* [XFS] Add lock annotations to xfs_trans_update_ail andJosh Triplett2006-09-281-5/+7
| | | | | | | | | | | | | | | | | xfs_trans_delete_ail xfs_trans_update_ail and xfs_trans_delete_ail get called with the AIL lock held, and release it. Add lock annotations to these two functions so that sparse can check callers for lock pairing, and so that sparse will not complain about these functions since they intentionally use locks in this manner. SGI-PV: 954580 SGI-Modid: xfs-linux-melb:xfs-kern:26807a Signed-off-by: Josh Triplett <josh@freedesktop.org> Signed-off-by: Nathan Scott <nathans@sgi.com> Signed-off-by: Tim Shimmin <tes@sgi.com>
* [XFS] Update license/copyright notices to match the prefered SGINathan Scott2005-11-021-25/+11
| | | | | | | | | boilerplate. SGI-PV: 913862 SGI-Modid: xfs-linux:xfs-kern:23903a Signed-off-by: Nathan Scott <nathans@sgi.com>
* Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds2005-04-161-0/+73
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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