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7caa47151a
This patchset implements IO cost model based work-conserving
proportional controller.
While io.latency provides the capability to comprehensively prioritize
and protect IOs depending on the cgroups, its protection is binary -
the lowest latency target cgroup which is suffering is protected at
the cost of all others. In many use cases including stacking multiple
workload containers in a single system, it's necessary to distribute
IO capacity with better granularity.
One challenge of controlling IO resources is the lack of trivially
observable cost metric. The most common metrics - bandwidth and iops
- can be off by orders of magnitude depending on the device type and
IO pattern. However, the cost isn't a complete mystery. Given
several key attributes, we can make fairly reliable predictions on how
expensive a given stream of IOs would be, at least compared to other
IO patterns.
The function which determines the cost of a given IO is the IO cost
model for the device. This controller distributes IO capacity based
on the costs estimated by such model. The more accurate the cost
model the better but the controller adapts based on IO completion
latency and as long as the relative costs across differents IO
patterns are consistent and sensible, it'll adapt to the actual
performance of the device.
Currently, the only implemented cost model is a simple linear one with
a few sets of default parameters for different classes of device.
This covers most common devices reasonably well. All the
infrastructure to tune and add different cost models is already in
place and a later patch will also allow using bpf progs for cost
models.
Please see the top comment in blk-iocost.c and documentation for
more details.
v2: Rebased on top of RQ_ALLOC_TIME changes and folded in Rik's fix
for a divide-by-zero bug in current_hweight() triggered by zero
inuse_sum.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andy Newell <newella@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
211 lines
6.2 KiB
Text
211 lines
6.2 KiB
Text
# SPDX-License-Identifier: GPL-2.0
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#
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# Block layer core configuration
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#
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menuconfig BLOCK
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bool "Enable the block layer" if EXPERT
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default y
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select SBITMAP
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select SRCU
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help
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Provide block layer support for the kernel.
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Disable this option to remove the block layer support from the
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kernel. This may be useful for embedded devices.
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If this option is disabled:
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- block device files will become unusable
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- some filesystems (such as ext3) will become unavailable.
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Also, SCSI character devices and USB storage will be disabled since
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they make use of various block layer definitions and facilities.
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Say Y here unless you know you really don't want to mount disks and
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suchlike.
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if BLOCK
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config BLK_RQ_ALLOC_TIME
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bool
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config BLK_SCSI_REQUEST
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bool
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config BLK_DEV_BSG
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bool "Block layer SG support v4"
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default y
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select BLK_SCSI_REQUEST
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help
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Saying Y here will enable generic SG (SCSI generic) v4 support
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for any block device.
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Unlike SG v3 (aka block/scsi_ioctl.c drivers/scsi/sg.c), SG v4
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can handle complicated SCSI commands: tagged variable length cdbs
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with bidirectional data transfers and generic request/response
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protocols (e.g. Task Management Functions and SMP in Serial
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Attached SCSI).
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This option is required by recent UDEV versions to properly
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access device serial numbers, etc.
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If unsure, say Y.
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config BLK_DEV_BSGLIB
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bool "Block layer SG support v4 helper lib"
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select BLK_DEV_BSG
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select BLK_SCSI_REQUEST
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help
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Subsystems will normally enable this if needed. Users will not
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normally need to manually enable this.
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If unsure, say N.
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config BLK_DEV_INTEGRITY
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bool "Block layer data integrity support"
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select CRC_T10DIF if BLK_DEV_INTEGRITY
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---help---
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Some storage devices allow extra information to be
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stored/retrieved to help protect the data. The block layer
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data integrity option provides hooks which can be used by
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filesystems to ensure better data integrity.
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Say yes here if you have a storage device that provides the
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T10/SCSI Data Integrity Field or the T13/ATA External Path
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Protection. If in doubt, say N.
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config BLK_DEV_ZONED
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bool "Zoned block device support"
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select MQ_IOSCHED_DEADLINE
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---help---
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Block layer zoned block device support. This option enables
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support for ZAC/ZBC host-managed and host-aware zoned block devices.
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Say yes here if you have a ZAC or ZBC storage device.
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config BLK_DEV_THROTTLING
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bool "Block layer bio throttling support"
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depends on BLK_CGROUP=y
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---help---
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Block layer bio throttling support. It can be used to limit
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the IO rate to a device. IO rate policies are per cgroup and
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one needs to mount and use blkio cgroup controller for creating
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cgroups and specifying per device IO rate policies.
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See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
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config BLK_DEV_THROTTLING_LOW
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bool "Block throttling .low limit interface support (EXPERIMENTAL)"
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depends on BLK_DEV_THROTTLING
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---help---
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Add .low limit interface for block throttling. The low limit is a best
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effort limit to prioritize cgroups. Depending on the setting, the limit
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can be used to protect cgroups in terms of bandwidth/iops and better
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utilize disk resource.
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Note, this is an experimental interface and could be changed someday.
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config BLK_CMDLINE_PARSER
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bool "Block device command line partition parser"
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---help---
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Enabling this option allows you to specify the partition layout from
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the kernel boot args. This is typically of use for embedded devices
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which don't otherwise have any standardized method for listing the
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partitions on a block device.
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See Documentation/block/cmdline-partition.rst for more information.
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config BLK_WBT
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bool "Enable support for block device writeback throttling"
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---help---
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Enabling this option enables the block layer to throttle buffered
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background writeback from the VM, making it more smooth and having
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less impact on foreground operations. The throttling is done
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dynamically on an algorithm loosely based on CoDel, factoring in
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the realtime performance of the disk.
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config BLK_CGROUP_IOLATENCY
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bool "Enable support for latency based cgroup IO protection"
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depends on BLK_CGROUP=y
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---help---
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Enabling this option enables the .latency interface for IO throttling.
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The IO controller will attempt to maintain average IO latencies below
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the configured latency target, throttling anybody with a higher latency
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target than the victimized group.
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Note, this is an experimental interface and could be changed someday.
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config BLK_CGROUP_IOCOST
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bool "Enable support for cost model based cgroup IO controller"
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depends on BLK_CGROUP=y
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select BLK_RQ_ALLOC_TIME
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---help---
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Enabling this option enables the .weight interface for cost
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model based proportional IO control. The IO controller
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distributes IO capacity between different groups based on
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their share of the overall weight distribution.
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config BLK_WBT_MQ
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bool "Multiqueue writeback throttling"
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default y
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depends on BLK_WBT
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---help---
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Enable writeback throttling by default on multiqueue devices.
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Multiqueue currently doesn't have support for IO scheduling,
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enabling this option is recommended.
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config BLK_DEBUG_FS
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bool "Block layer debugging information in debugfs"
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default y
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depends on DEBUG_FS
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---help---
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Include block layer debugging information in debugfs. This information
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is mostly useful for kernel developers, but it doesn't incur any cost
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at runtime.
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Unless you are building a kernel for a tiny system, you should
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say Y here.
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config BLK_DEBUG_FS_ZONED
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bool
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default BLK_DEBUG_FS && BLK_DEV_ZONED
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config BLK_SED_OPAL
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bool "Logic for interfacing with Opal enabled SEDs"
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---help---
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Builds Logic for interfacing with Opal enabled controllers.
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Enabling this option enables users to setup/unlock/lock
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Locking ranges for SED devices using the Opal protocol.
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menu "Partition Types"
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source "block/partitions/Kconfig"
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endmenu
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endif # BLOCK
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config BLOCK_COMPAT
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bool
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depends on BLOCK && COMPAT
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default y
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config BLK_MQ_PCI
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bool
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depends on BLOCK && PCI
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default y
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config BLK_MQ_VIRTIO
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bool
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depends on BLOCK && VIRTIO
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default y
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config BLK_MQ_RDMA
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bool
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depends on BLOCK && INFINIBAND
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default y
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config BLK_PM
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def_bool BLOCK && PM
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source "block/Kconfig.iosched"
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