2005-11-04 07:43:35 +00:00
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#
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# Makefile for the kernel block layer
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#
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2014-05-19 14:16:41 +00:00
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obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-tag.o blk-sysfs.o \
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2010-09-03 09:56:16 +00:00
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blk-flush.o blk-settings.o blk-ioc.o blk-map.o \
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2008-09-14 12:55:09 +00:00
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blk-exec.o blk-merge.o blk-softirq.o blk-timeout.o \
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blk-mq: new multi-queue block IO queueing mechanism
Linux currently has two models for block devices:
- The classic request_fn based approach, where drivers use struct
request units for IO. The block layer provides various helper
functionalities to let drivers share code, things like tag
management, timeout handling, queueing, etc.
- The "stacked" approach, where a driver squeezes in between the
block layer and IO submitter. Since this bypasses the IO stack,
driver generally have to manage everything themselves.
With drivers being written for new high IOPS devices, the classic
request_fn based driver doesn't work well enough. The design dates
back to when both SMP and high IOPS was rare. It has problems with
scaling to bigger machines, and runs into scaling issues even on
smaller machines when you have IOPS in the hundreds of thousands
per device.
The stacked approach is then most often selected as the model
for the driver. But this means that everybody has to re-invent
everything, and along with that we get all the problems again
that the shared approach solved.
This commit introduces blk-mq, block multi queue support. The
design is centered around per-cpu queues for queueing IO, which
then funnel down into x number of hardware submission queues.
We might have a 1:1 mapping between the two, or it might be
an N:M mapping. That all depends on what the hardware supports.
blk-mq provides various helper functions, which include:
- Scalable support for request tagging. Most devices need to
be able to uniquely identify a request both in the driver and
to the hardware. The tagging uses per-cpu caches for freed
tags, to enable cache hot reuse.
- Timeout handling without tracking request on a per-device
basis. Basically the driver should be able to get a notification,
if a request happens to fail.
- Optional support for non 1:1 mappings between issue and
submission queues. blk-mq can redirect IO completions to the
desired location.
- Support for per-request payloads. Drivers almost always need
to associate a request structure with some driver private
command structure. Drivers can tell blk-mq this at init time,
and then any request handed to the driver will have the
required size of memory associated with it.
- Support for merging of IO, and plugging. The stacked model
gets neither of these. Even for high IOPS devices, merging
sequential IO reduces per-command overhead and thus
increases bandwidth.
For now, this is provided as a potential 3rd queueing model, with
the hope being that, as it matures, it can replace both the classic
and stacked model. That would get us back to having just 1 real
model for block devices, leaving the stacked approach to dm/md
devices (as it was originally intended).
Contributions in this patch from the following people:
Shaohua Li <shli@fusionio.com>
Alexander Gordeev <agordeev@redhat.com>
Christoph Hellwig <hch@infradead.org>
Mike Christie <michaelc@cs.wisc.edu>
Matias Bjorling <m@bjorling.me>
Jeff Moyer <jmoyer@redhat.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-10-24 08:20:05 +00:00
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blk-iopoll.o blk-lib.o blk-mq.o blk-mq-tag.o \
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blk-mq-sysfs.o blk-mq-cpu.o blk-mq-cpumap.o ioctl.o \
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2014-05-19 17:02:18 +00:00
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genhd.o scsi_ioctl.o partition-generic.o ioprio.o \
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partitions/
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2005-11-04 07:43:35 +00:00
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2014-05-20 02:01:52 +00:00
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obj-$(CONFIG_BOUNCE) += bounce.o
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2007-07-09 10:38:05 +00:00
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obj-$(CONFIG_BLK_DEV_BSG) += bsg.o
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2011-07-31 20:05:09 +00:00
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obj-$(CONFIG_BLK_DEV_BSGLIB) += bsg-lib.o
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2009-12-03 17:59:42 +00:00
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obj-$(CONFIG_BLK_CGROUP) += blk-cgroup.o
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2010-09-15 21:06:35 +00:00
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obj-$(CONFIG_BLK_DEV_THROTTLING) += blk-throttle.o
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2005-11-04 07:43:35 +00:00
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obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
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obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
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obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
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2018-02-27 17:09:03 +00:00
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obj-$(CONFIG_IOSCHED_FIFO) += fifo-iosched.o
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obj-$(CONFIG_IOSCHED_FIOPS) += fiops-iosched.o
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obj-$(CONFIG_IOSCHED_SIO) += sio-iosched.o
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obj-$(CONFIG_IOSCHED_SIOPLUS) += sioplus-iosched.o
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obj-$(CONFIG_IOSCHED_TRIPNDROID)+= tripndroid-iosched.o
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obj-$(CONFIG_IOSCHED_VR) += vr-iosched.o
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obj-$(CONFIG_IOSCHED_ZEN) += zen-iosched.o
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Add BFQ I/O Scheduler. Enable ROW I/Q Scheduler in Makefile.
Add the BFQ-v7r8 I/O scheduler to 3.18.0.
The general structure is borrowed from CFQ, as much of the code for
handling I/O contexts. Over time, several useful features have been
ported from CFQ as well (details in the changelog in README.BFQ). A
(bfq_)queue is associated to each task doing I/O on a device, and each
time a scheduling decision has to be made a queue is selected and served
until it expires.
- Slices are given in the service domain: tasks are assigned
budgets, measured in number of sectors. Once got the disk, a task
must however consume its assigned budget within a configurable
maximum time (by default, the maximum possible value of the
budgets is automatically computed to comply with this timeout).
This allows the desired latency vs "throughput boosting" tradeoff
to be set.
- Budgets are scheduled according to a variant of WF2Q+, implemented
using an augmented rb-tree to take eligibility into account while
preserving an O(log N) overall complexity.
- A low-latency tunable is provided; if enabled, both interactive
and soft real-time applications are guaranteed a very low latency.
- Latency guarantees are preserved also in the presence of NCQ.
- Also with flash-based devices, a high throughput is achieved
while still preserving latency guarantees.
- BFQ features Early Queue Merge (EQM), a sort of fusion of the
cooperating-queue-merging and the preemption mechanisms present
in CFQ. EQM is in fact a unified mechanism that tries to get a
sequential read pattern, and hence a high throughput, with any
set of processes performing interleaved I/O over a contiguous
sequence of sectors.
- BFQ supports full hierarchical scheduling, exporting a cgroups
interface. Since each node has a full scheduler, each group can
be assigned its own weight.
- If the cgroups interface is not used, only I/O priorities can be
assigned to processes, with ioprio values mapped to weights
with the relation weight = IOPRIO_BE_NR - ioprio.
- ioprio classes are served in strict priority order, i.e., lower
priority queues are not served as long as there are higher
priority queues. Among queues in the same class the bandwidth is
distributed in proportion to the weight of each queue. A very
thin extra bandwidth is however guaranteed to the Idle class, to
prevent it from starving.
Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Tkkg1994 <luca.grifo@outlook.com>
Signed-off-by: djb77 <dwayne.bakewell@gmail.com>
2018-07-19 12:10:48 +00:00
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obj-$(CONFIG_IOSCHED_ROW) += row-iosched.o
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obj-$(CONFIG_IOSCHED_BFQ) += bfq-iosched.o
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2018-02-28 16:43:20 +00:00
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obj-$(CONFIG_IOSCHED_MAPLE) += maple-iosched.o
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2006-03-23 19:00:26 +00:00
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2007-10-12 10:50:41 +00:00
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obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o
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2013-09-30 20:45:19 +00:00
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obj-$(CONFIG_BLK_CMDLINE_PARSER) += cmdline-parser.o
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2014-09-26 23:20:07 +00:00
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obj-$(CONFIG_BLK_DEV_INTEGRITY) += bio-integrity.o blk-integrity.o t10-pi.o
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