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Modify the Block I/O cgroup subsystem to be able to be built as a module.
As the CFQ disk scheduler optionally depends on blk-cgroup, config options
in block/Kconfig, block/Kconfig.iosched, and block/blk-cgroup.h are
enhanced to support the new module dependency.
Signed-off-by: Ben Blum <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Paul Menage <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Cc: Lai Jiangshan <[email protected]>
Cc: Vivek Goyal <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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On 64 bit builds when CONFIG_BLK_CGROUP=n (the default) this removes 8
bytes of padding from structure io_context and drops its size from 72 to
64 bytes, so needing one fewer cachelines and allowing more objects per
slab in it's kmem_cache.
Signed-off-by: Richard Kennedy <[email protected]>
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patch against 2.6.33
compiled & test on x86_64 AMDX2
regards
Richard
Signed-off-by: Jens Axboe <[email protected]>
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It isn't used anymore, since AS was deleted.
Signed-off-by: Jens Axboe <[email protected]>
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With CLONE_IO, parent's io_context->nr_tasks is incremented, but never
decremented whenever copy_process() fails afterwards, which prevents
exit_io_context() from calling IO schedulers exit functions.
Give a task_struct to exit_io_context(), and call exit_io_context() instead of
put_io_context() in copy_process() cleanup path.
Signed-off-by: Louis Rilling <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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o This is basic implementation of blkio controller cgroup interface. This is
the common interface visible to user space and should be used by different
IO control policies as we implement those.
Signed-off-by: Vivek Goyal <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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async cfq_queue's are already shared between processes within the same
priority, and forthcoming patches will change the mapping of cic to sync
cfq_queue from 1:1 to 1:N. So, calculate the seekiness of a process
based on the cfq_queue instead of the cfq_io_context.
Signed-off-by: Jeff Moyer <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Commit d9c7d394a8ebacb60097b192939ae9f15235225e
("block: prevent possible io_context->refcount overflow") mistakenly
changed atomic_inc(&ioc->nr_tasks) to atomic_long_inc(&ioc->refcount).
Signed-off-by: Li Zefan <[email protected]>
Acked-by: Nikanth Karthikesan <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Currently io_context has an atomic_t(32-bit) as refcount. In the case of
cfq, for each device against whcih a task does I/O, a reference to the
io_context would be taken. And when there are multiple process sharing
io_contexts(CLONE_IO) would also have a reference to the same io_context.
Theoretically the possible maximum number of processes sharing the same
io_context + the number of disks/cfq_data referring to the same io_context
can overflow the 32-bit counter on a very high-end machine.
Even though it is an improbable case, let us make it atomic_long_t.
Signed-off-by: Nikanth Karthikesan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Signed-off-by: Jens Axboe <[email protected]>
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Thanks to Nikanth Karthikesan <[email protected]> for reporting this.
Signed-off-by: Jens Axboe <[email protected]>
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SLAB_DESTROY_BY_RCU is not a direct substitute for normal call_rcu()
freeing, since it'll page freeing but NOT object freeing. So change
cfq to do the freeing on its own.
Signed-off-by: Fabio Checconi <[email protected]>
Acked-by: Paul E. McKenney <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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It's cumbersome to browse a radix tree from start to finish, especially
since we modify keys when a process exits. So add a hlist for the single
purpose of browsing over all known cfq_io_contexts, used for exit,
io prio change, etc.
This fixes http://bugzilla.kernel.org/show_bug.cgi?id=9948
Signed-off-by: Jens Axboe <[email protected]>
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The io context sharing introduced a per-ioc spinlock, that would protect
the cfq io context lookup. That is a regression from the original, since
we never needed any locking there because the ioc/cic were process private.
The cic lookup is changed from an rbtree construct to a radix tree, which
we can then use RCU to make the reader side lockless. That is the performance
critical path, modifying the radix tree is only done on process creation
(when that process first does IO, actually) and on process exit (if that
process has done IO).
As it so happens, radix trees are also much faster for this type of
lookup where the key is a pointer. It's a very sparse tree.
Signed-off-by: Jens Axboe <[email protected]>
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Detach task state from ioc, instead keep track of how many processes
are accessing the ioc.
Signed-off-by: Jens Axboe <[email protected]>
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This is where it belongs and then it doesn't take up space for a
process that doesn't do IO.
Signed-off-by: Jens Axboe <[email protected]>
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