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* mm: per device dirty thresholdPeter Zijlstra2007-10-171-5/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Scale writeback cache per backing device, proportional to its writeout speed. By decoupling the BDI dirty thresholds a number of problems we currently have will go away, namely: - mutual interference starvation (for any number of BDIs); - deadlocks with stacked BDIs (loop, FUSE and local NFS mounts). It might be that all dirty pages are for a single BDI while other BDIs are idling. By giving each BDI a 'fair' share of the dirty limit, each one can have dirty pages outstanding and make progress. A global threshold also creates a deadlock for stacked BDIs; when A writes to B, and A generates enough dirty pages to get throttled, B will never start writeback until the dirty pages go away. Again, by giving each BDI its own 'independent' dirty limit, this problem is avoided. So the problem is to determine how to distribute the total dirty limit across the BDIs fairly and efficiently. A DBI that has a large dirty limit but does not have any dirty pages outstanding is a waste. What is done is to keep a floating proportion between the DBIs based on writeback completions. This way faster/more active devices get a larger share than slower/idle devices. [akpm@linux-foundation.org: fix warnings] [hugh@veritas.com: Fix occasional hang when a task couldn't get out of balance_dirty_pages] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: scalable bdi statistics countersPeter Zijlstra2007-10-171-0/+27
| | | | | | | | Provide scalable per backing_dev_info statistics counters. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* nfs: remove congestion_end()Peter Zijlstra2007-10-171-13/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | These patches aim to improve balance_dirty_pages() and directly address three issues: 1) inter device starvation 2) stacked device deadlocks 3) inter process starvation 1 and 2 are a direct result from removing the global dirty limit and using per device dirty limits. By giving each device its own dirty limit is will no longer starve another device, and the cyclic dependancy on the dirty limit is broken. In order to efficiently distribute the dirty limit across the independant devices a floating proportion is used, this will allocate a share of the total limit proportional to the device's recent activity. 3 is done by also scaling the dirty limit proportional to the current task's recent dirty rate. This patch: nfs: remove congestion_end(). It's redundant, clear_bdi_congested() already wakes the waiters. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* remove mm/backing-dev.c:congestion_wait_interruptible()Adrian Bunk2007-07-161-16/+0
| | | | | | | | | congestion_wait_interruptible() is no longer used. Signed-off-by: Adrian Bunk <bunk@stusta.de> Acked-by: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] nfs: fix congestion controlPeter Zijlstra2007-03-161-0/+16
| | | | | | | | | | | | | | | | | | | The current NFS client congestion logic is severly broken, it marks the backing device congested during each nfs_writepages() call but doesn't mirror this in nfs_writepage() which makes for deadlocks. Also it implements its own waitqueue. Replace this by a more regular congestion implementation that puts a cap on the number of active writeback pages and uses the bdi congestion waitqueue. Also always use an interruptible wait since it makes sense to be able to SIGKILL the process even for mounts without 'intr'. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] separate bdi congestion functions from queue congestion functionsAndrew Morton2006-10-201-0/+69
Separate out the concept of "queue congestion" from "backing-dev congestion". Congestion is a backing-dev concept, not a queue concept. The blk_* congestion functions are retained, as wrappers around the core backing-dev congestion functions. This proper layering is needed so that NFS can cleanly use the congestion functions, and so that CONFIG_BLOCK=n actually links. Cc: "Thomas Maier" <balagi@justmail.de> Cc: "Jens Axboe" <jens.axboe@oracle.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: David Howells <dhowells@redhat.com> Cc: Peter Osterlund <petero2@telia.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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