09 Jul, 2018
3 commits
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Current IO controllers for the block layer are less than ideal for our
use case. The io.max controller is great at hard limiting, but it is
not work conserving. This patch introduces io.latency. You provide a
latency target for your group and we monitor the io in short windows to
make sure we are not exceeding those latency targets. This makes use of
the rq-qos infrastructure and works much like the wbt stuff. There are
a few differences from wbt- It's bio based, so the latency covers the whole block layer in addition to
the actual io.
- We will throttle all IO types that comes in here if we need to.
- We use the mean latency over the 100ms window. This is because writes can
be particularly fast, which could give us a false sense of the impact of
other workloads on our protected workload.
- By default there's no throttling, we set the queue_depth to INT_MAX so that
we can have as many outstanding bio's as we're allowed to. Only at
throttle time do we pay attention to the actual queue depth.
- We backcharge cgroups for root cg issued IO and induce artificial
delays in order to deal with cases like metadata only or swap heavy
workloads.In testing this has worked out relatively well. Protected workloads
will throttle noisy workloads down to 1 io at time if they are doing
normal IO on their own, or induce up to a 1 second delay per syscall if
they are doing a lot of root issued IO (metadata/swap IO).Our testing has revolved mostly around our production web servers where
we have hhvm (the web server application) in a protected group and
everything else in another group. We see slightly higher requests per
second (RPS) on the test tier vs the control tier, and much more stable
RPS across all machines in the test tier vs the control tier.Another test we run is a slow memory allocator in the unprotected group.
Before this would eventually push us into swap and cause the whole box
to die and not recover at all. With these patches we see slight RPS
drops (usually 10-15%) before the memory consumer is properly killed and
things recover within seconds.Signed-off-by: Josef Bacik
Acked-by: Tejun Heo
Signed-off-by: Jens Axboe -
blkcg-qos is going to do essentially what wbt does, only on a cgroup
basis. Break out the common code that will be shared between blkcg-qos
and wbt into blk-rq-qos.* so they can both utilize the same
infrastructure.Signed-off-by: Josef Bacik
Signed-off-by: Jens Axboe -
Exclude zoned block device members from struct request_queue for
CONFIG_BLK_DEV_ZONED == n. Avoid breaking the build by only building
the code that uses these struct request_queue members if
CONFIG_BLK_DEV_ZONED != n.Signed-off-by: Bart Van Assche
Reviewed-by: Damien Le Moal
Cc: Matias Bjorling
Cc: Christoph Hellwig
Signed-off-by: Jens Axboe
02 Nov, 2017
1 commit
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
09 Aug, 2017
1 commit
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Like pci and virtio, we add a rdma helper for affinity
spreading. This achieves optimal mq affinity assignments
according to the underlying rdma device affinity maps.Reviewed-by: Jens Axboe
Reviewed-by: Christoph Hellwig
Reviewed-by: Max Gurtovoy
Signed-off-by: Sagi Grimberg
Signed-off-by: Doug Ledford
19 Apr, 2017
2 commits
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The BFQ I/O scheduler features an optimal fair-queuing
(proportional-share) scheduling algorithm, enriched with several
mechanisms to boost throughput and reduce latency for interactive and
real-time applications. This makes BFQ a large and complex piece of
code. This commit addresses this issue by splitting BFQ into three
main, independent components, and by moving each component into a
separate source file:
1. Main algorithm: handles the interaction with the kernel, and
decides which requests to dispatch; it uses the following two further
components to achieve its goals.
2. Scheduling engine (Hierarchical B-WF2Q+ scheduling algorithm):
computes the schedule, using weights and budgets provided by the above
component.
3. cgroups support: handles group operations (creation, destruction,
move, ...).Signed-off-by: Paolo Valente
Signed-off-by: Jens Axboe -
We tag as v0 the version of BFQ containing only BFQ's engine plus
hierarchical support. BFQ's engine is introduced by this commit, while
hierarchical support is added by next commit. We use the v0 tag to
distinguish this minimal version of BFQ from the versions containing
also the features and the improvements added by next commits. BFQ-v0
coincides with the version of BFQ submitted a few years ago [1], apart
from the introduction of preemption, described below.BFQ is a proportional-share I/O scheduler, whose general structure,
plus a lot of code, are borrowed from CFQ.- Each process doing I/O on a device is associated with a weight and a
(bfq_)queue.- BFQ grants exclusive access to the device, for a while, to one queue
(process) at a time, and implements this service model by
associating every queue with a budget, measured in number of
sectors.- After a queue is granted access to the device, the budget of the
queue is decremented, on each request dispatch, by the size of the
request.- The in-service queue is expired, i.e., its service is suspended,
only if one of the following events occurs: 1) the queue finishes
its budget, 2) the queue empties, 3) a "budget timeout" fires.- The budget timeout prevents processes doing random I/O from
holding the device for too long and dramatically reducing
throughput.- Actually, as in CFQ, a queue associated with a process issuing
sync requests may not be expired immediately when it empties. In
contrast, BFQ may idle the device for a short time interval,
giving the process the chance to go on being served if it issues
a new request in time. Device idling typically boosts the
throughput on rotational devices, if processes do synchronous
and sequential I/O. In addition, under BFQ, device idling is
also instrumental in guaranteeing the desired throughput
fraction to processes issuing sync requests (see [2] for
details).- With respect to idling for service guarantees, if several
processes are competing for the device at the same time, but
all processes (and groups, after the following commit) have
the same weight, then BFQ guarantees the expected throughput
distribution without ever idling the device. Throughput is
thus as high as possible in this common scenario.- Queues are scheduled according to a variant of WF2Q+, named
B-WF2Q+, and implemented using an augmented rb-tree to preserve an
O(log N) overall complexity. See [2] for more details. B-WF2Q+ is
also ready for hierarchical scheduling. However, for a cleaner
logical breakdown, the code that enables and completes
hierarchical support is provided in the next commit, which focuses
exactly on this feature.- B-WF2Q+ guarantees a tight deviation with respect to an ideal,
perfectly fair, and smooth service. In particular, B-WF2Q+
guarantees that each queue receives a fraction of the device
throughput proportional to its weight, even if the throughput
fluctuates, and regardless of: the device parameters, the current
workload and the budgets assigned to the queue.- The last, budget-independence, property (although probably
counterintuitive in the first place) is definitely beneficial, for
the following reasons:- First, with any proportional-share scheduler, the maximum
deviation with respect to an ideal service is proportional to
the maximum budget (slice) assigned to queues. As a consequence,
BFQ can keep this deviation tight not only because of the
accurate service of B-WF2Q+, but also because BFQ *does not*
need to assign a larger budget to a queue to let the queue
receive a higher fraction of the device throughput.- Second, BFQ is free to choose, for every process (queue), the
budget that best fits the needs of the process, or best
leverages the I/O pattern of the process. In particular, BFQ
updates queue budgets with a simple feedback-loop algorithm that
allows a high throughput to be achieved, while still providing
tight latency guarantees to time-sensitive applications. When
the in-service queue expires, this algorithm computes the next
budget of the queue so as to:- Let large budgets be eventually assigned to the queues
associated with I/O-bound applications performing sequential
I/O: in fact, the longer these applications are served once
got access to the device, the higher the throughput is.- Let small budgets be eventually assigned to the queues
associated with time-sensitive applications (which typically
perform sporadic and short I/O), because, the smaller the
budget assigned to a queue waiting for service is, the sooner
B-WF2Q+ will serve that queue (Subsec 3.3 in [2]).- Weights can be assigned to processes only indirectly, through I/O
priorities, and according to the relation:
weight = 10 * (IOPRIO_BE_NR - ioprio).
The next patch provides, instead, a cgroups interface through which
weights can be assigned explicitly.- If several processes are competing for the device at the same time,
but all processes and groups have the same weight, then BFQ
guarantees the expected throughput distribution without ever idling
the device. It uses preemption instead. Throughput is then much
higher in this common scenario.- 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.- If the strict_guarantees parameter is set (default: unset), then BFQ
- always performs idling when the in-service queue becomes empty;
- forces the device to serve one I/O request at a time, by
dispatching a new request only if there is no outstanding
request.
In the presence of differentiated weights or I/O-request sizes,
both the above conditions are needed to guarantee that every
queue receives its allotted share of the bandwidth (see
Documentation/block/bfq-iosched.txt for more details). Setting
strict_guarantees may evidently affect throughput.[1] https://lkml.org/lkml/2008/4/1/234
https://lkml.org/lkml/2008/11/11/148[2] P. Valente and M. Andreolini, "Improving Application
Responsiveness with the BFQ Disk I/O Scheduler", Proceedings of
the 5th Annual International Systems and Storage Conference
(SYSTOR '12), June 2012.
Slightly extended version:
http://algogroup.unimore.it/people/paolo/disk_sched/bfq-v1-suite-
results.pdfSigned-off-by: Fabio Checconi
Signed-off-by: Paolo Valente
Signed-off-by: Arianna Avanzini
Signed-off-by: Jens Axboe
15 Apr, 2017
1 commit
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The Kyber I/O scheduler is an I/O scheduler for fast devices designed to
scale to multiple queues. Users configure only two knobs, the target
read and synchronous write latencies, and the scheduler tunes itself to
achieve that latency goal.The implementation is based on "tokens", built on top of the scalable
bitmap library. Tokens serve as a mechanism for limiting requests. There
are two tiers of tokens: queueing tokens and dispatch tokens.A queueing token is required to allocate a request. In fact, these
tokens are actually the blk-mq internal scheduler tags, but the
scheduler manages the allocation directly in order to implement its
policy.Dispatch tokens are device-wide and split up into two scheduling
domains: reads vs. writes. Each hardware queue dispatches batches
round-robin between the scheduling domains as long as tokens are
available for that domain.These tokens can be used as the mechanism to enable various policies.
The policy Kyber uses is inspired by active queue management techniques
for network routing, similar to blk-wbt. The scheduler monitors
latencies and scales the number of dispatch tokens accordingly. Queueing
tokens are used to prevent starvation of synchronous requests by
asynchronous requests.Various extensions are possible, including better heuristics and ionice
support. The new scheduler isn't set as the default yet.Signed-off-by: Omar Sandoval
Signed-off-by: Jens Axboe
03 Mar, 2017
1 commit
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Pull vhost updates from Michael Tsirkin:
"virtio, vhost: optimizations, fixesLooks like a quiet cycle for vhost/virtio, just a couple of minor
tweaks. Most notable is automatic interrupt affinity for blk and scsi.
Hopefully other devices are not far behind"* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
virtio-console: avoid DMA from stack
vhost: introduce O(1) vq metadata cache
virtio_scsi: use virtio IRQ affinity
virtio_blk: use virtio IRQ affinity
blk-mq: provide a default queue mapping for virtio device
virtio: provide a method to get the IRQ affinity mask for a virtqueue
virtio: allow drivers to request IRQ affinity when creating VQs
virtio_pci: simplify MSI-X setup
virtio_pci: don't duplicate the msix_enable flag in struct pci_dev
virtio_pci: use shared interrupts for virtqueues
virtio_pci: remove struct virtio_pci_vq_info
vhost: try avoiding avail index access when getting descriptor
virtio_mmio: expose header to userspace
28 Feb, 2017
1 commit
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Similar to the PCI version, just calling into virtio instead.
Signed-off-by: Christoph Hellwig
Signed-off-by: Michael S. Tsirkin
18 Feb, 2017
1 commit
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Signed-off-by: Jens Axboe
07 Feb, 2017
1 commit
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This patch implements the necessary logic to bring an Opal
enabled drive out of a factory-enabled into a working
Opal state.This patch set also enables logic to save a password to
be replayed during a resume from suspend.Signed-off-by: Scott Bauer
Signed-off-by: Rafael Antognolli
Reviewed-by: Christoph Hellwig
Signed-off-by: Jens Axboe
01 Feb, 2017
1 commit
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We only need this code to support scsi, ide, cciss and virtio. And at
least for virtio it's a deprecated feature to start with.This should shrink the kernel size for embedded device that only use,
say eMMC a bit.Signed-off-by: Christoph Hellwig
Signed-off-by: Jens Axboe
28 Jan, 2017
1 commit
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This fixes a couple of problems:
1. In the !CONFIG_DEBUG_FS case, the stub definitions were bogus.
2. In the !CONFIG_BLOCK case, blk-mq-debugfs.c shouldn't be compiled at
all.Fix the stub definitions and add a CONFIG_BLK_DEBUG_FS Kconfig option.
Fixes: 07e4fead45e6 ("blk-mq: create debugfs directory tree")
Signed-off-by: Omar SandovalAugment Kconfig description.
Signed-off-by: Jens Axboe
27 Jan, 2017
1 commit
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In preparation for putting blk-mq debugging information in debugfs,
create a directory tree mirroring the one in sysfs:# tree -d /sys/kernel/debug/block
/sys/kernel/debug/block
|-- nvme0n1
| `-- mq
| |-- 0
| | `-- cpu0
| |-- 1
| | `-- cpu1
| |-- 2
| | `-- cpu2
| `-- 3
| `-- cpu3
`-- vda
`-- mq
`-- 0
|-- cpu0
|-- cpu1
|-- cpu2
`-- cpu3Also add the scaffolding for the actual files that will go in here,
either under the hardware queue or software queue directories.Reviewed-by: Hannes Reinecke
Signed-off-by: Omar Sandoval
Signed-off-by: Jens Axboe
18 Jan, 2017
2 commits
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This is basically identical to deadline-iosched, except it registers
as a MQ capable scheduler. This is still a single queue design.Signed-off-by: Jens Axboe
Reviewed-by: Bart Van Assche
Reviewed-by: Omar Sandoval -
This adds a set of hooks that intercepts the blk-mq path of
allocating/inserting/issuing/completing requests, allowing
us to develop a scheduler within that framework.We reuse the existing elevator scheduler API on the registration
side, but augment that with the scheduler flagging support for
the blk-mq interfce, and with a separate set of ops hooks for MQ
devices.We split driver and scheduler tags, so we can run the scheduling
independently of device queue depth.Signed-off-by: Jens Axboe
Reviewed-by: Bart Van Assche
Reviewed-by: Omar Sandoval
11 Nov, 2016
2 commits
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We can hook this up to the block layer, to help throttle buffered
writes.wbt registers a few trace points that can be used to track what is
happening in the system:wbt_lat: 259:0: latency 2446318
wbt_stat: 259:0: rmean=2446318, rmin=2446318, rmax=2446318, rsamples=1,
wmean=518866, wmin=15522, wmax=5330353, wsamples=57
wbt_step: 259:0: step down: step=1, window=72727272, background=8, normal=16, max=32This shows a sync issue event (wbt_lat) that exceeded it's time. wbt_stat
dumps the current read/write stats for that window, and wbt_step shows a
step down event where we now scale back writes. Each trace includes the
device, 259:0 in this case.Signed-off-by: Jens Axboe
-
For legacy block, we simply track them in the request queue. For
blk-mq, we track them on a per-sw queue basis, which we can then
sum up through the hardware queues and finally to a per device
state.The stats are tracked in, roughly, 0.1s interval windows.
Add sysfs files to display the stats.
The feature is off by default, to avoid any extra overhead. In-kernel
users of it can turn it on by setting QUEUE_FLAG_STATS in the queue
flags. We currently don't turn it on if someone just reads any of
the stats files, that is something we could add as well.Signed-off-by: Jens Axboe
19 Oct, 2016
1 commit
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Implement zoned block device zone information reporting and reset.
Zone information are reported as struct blk_zone. This implementation
does not differentiate between host-aware and host-managed device
models and is valid for both. Two functions are provided:
blkdev_report_zones for discovering the zone configuration of a
zoned block device, and blkdev_reset_zones for resetting the write
pointer of sequential zones. The helper function blk_queue_zone_size
and bdev_zone_size are also provided for, as the name suggest,
obtaining the zone size (in 512B sectors) of the zones of the device.Signed-off-by: Hannes Reinecke
[Damien: * Removed the zone cache
* Implement report zones operation based on earlier proposal
by Shaun Tancheff ]
Signed-off-by: Damien Le Moal
Reviewed-by: Christoph Hellwig
Reviewed-by: Martin K. Petersen
Reviewed-by: Shaun Tancheff
Tested-by: Shaun Tancheff
Signed-off-by: Jens Axboe
10 Oct, 2016
1 commit
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Pull blk-mq CPU hotplug update from Jens Axboe:
"This is the conversion of blk-mq to the new hotplug state machine"* 'for-4.9/block-smp' of git://git.kernel.dk/linux-block:
blk-mq: fixup "Convert to new hotplug state machine"
blk-mq: Convert to new hotplug state machine
blk-mq/cpu-notif: Convert to new hotplug state machine
22 Sep, 2016
1 commit
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Replace the block-mq notifier list management with the multi instance
facility in the cpu hotplug state machine.Signed-off-by: Thomas Gleixner
Cc: Peter Zijlstra
Cc: linux-block@vger.kernel.org
Cc: rt@linutronix.de
Cc: Christoph Hellwing
Signed-off-by: Jens Axboe
19 Sep, 2016
1 commit
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and building block/blk-mq-pci.o should depend on CONFIG_BLOCK
Fixes: 973c4e372c8f ("blk-mq: provide a default queue mapping for PCI device")
Signed-off-by: Stephen Rothwell
Reviewed-by: Christoph Hellwig
Signed-off-by: Jens Axboe
15 Sep, 2016
1 commit
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Signed-off-by: Christoph Hellwig
Reviewed-by: Keith Busch
Signed-off-by: Jens Axboe
24 Jan, 2016
1 commit
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Pull rdma updates from Doug Ledford:
"Initial roundup of 4.5 merge window patches- Remove usage of ib_query_device and instead store attributes in
ib_device struct- Move iopoll out of block and into lib, rename to irqpoll, and use
in several places in the rdma stack as our new completion queue
polling library mechanism. Update the other block drivers that
already used iopoll to use the new mechanism too.- Replace the per-entry GID table locks with a single GID table lock
- IPoIB multicast cleanup
- Cleanups to the IB MR facility
- Add support for 64bit extended IB counters
- Fix for netlink oops while parsing RDMA nl messages
- RoCEv2 support for the core IB code
- mlx4 RoCEv2 support
- mlx5 RoCEv2 support
- Cross Channel support for mlx5
- Timestamp support for mlx5
- Atomic support for mlx5
- Raw QP support for mlx5
- MAINTAINERS update for mlx4/mlx5
- Misc ocrdma, qib, nes, usNIC, cxgb3, cxgb4, mlx4, mlx5 updates
- Add support for remote invalidate to the iSER driver (pushed
through the RDMA tree due to dependencies, acknowledged by nab)- Update to NFSoRDMA (pushed through the RDMA tree due to
dependencies, acknowledged by Bruce)"* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma: (169 commits)
IB/mlx5: Unify CQ create flags check
IB/mlx5: Expose Raw Packet QP to user space consumers
{IB, net}/mlx5: Move the modify QP operation table to mlx5_ib
IB/mlx5: Support setting Ethernet priority for Raw Packet QPs
IB/mlx5: Add Raw Packet QP query functionality
IB/mlx5: Add create and destroy functionality for Raw Packet QP
IB/mlx5: Refactor mlx5_ib_qp to accommodate other QP types
IB/mlx5: Allocate a Transport Domain for each ucontext
net/mlx5_core: Warn on unsupported events of QP/RQ/SQ
net/mlx5_core: Add RQ and SQ event handling
net/mlx5_core: Export transport objects
IB/mlx5: Expose CQE version to user-space
IB/mlx5: Add CQE version 1 support to user QPs and SRQs
IB/mlx5: Fix data validation in mlx5_ib_alloc_ucontext
IB/sa: Fix netlink local service GFP crash
IB/srpt: Remove redundant wc array
IB/qib: Improve ipoib UD performance
IB/mlx4: Advertise RoCE v2 support
IB/mlx4: Create and use another QP1 for RoCEv2
IB/mlx4: Enable send of RoCE QP1 packets with IP/UDP headers
...
09 Jan, 2016
1 commit
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Take the core badblocks implementation from md, and make it generally
available. This follows the same style as kernel implementations of
linked lists, rb-trees etc, where you can have a structure that can be
embedded anywhere, and accessor functions to manipulate the data.The only changes in this copy of the code are ones to generalize
function/variable names from md-specific ones. Also add init and free
functions.Signed-off-by: Vishal Verma
Signed-off-by: Dan Williams
12 Dec, 2015
1 commit
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The new name is irq_poll as iopoll is already taken. Better suggestions
welcome.Signed-off-by: Christoph Hellwig
Reviewed-by: Bart Van Assche
27 Sep, 2014
1 commit
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The T10 Protection Information format is also used by some devices that
do not go through the SCSI layer (virtual block devices, NVMe). Relocate
the relevant functions to a block layer library that can be used without
involving SCSI.Signed-off-by: Martin K. Petersen
Reviewed-by: Christoph Hellwig
Signed-off-by: Jens Axboe
20 May, 2014
2 commits
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Continue moving some of the block files that are scattered around.
bounce.c contains only code for bouncing the contents of a bio.
It's block proper code, not mm code.Suggested-by: Ming Lei
Signed-off-by: Jens Axboe -
Like commit f9c78b2b, move this block related file outside
of fs/ and into the core block directory, block/.Signed-off-by: Jens Axboe
19 May, 2014
1 commit
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They really belong in block/, especially now since it's not in
drivers/block/ anymore. Additionally, the get_maintainer script
gets it wrong when in fs/.Suggested-by: Christoph Hellwig
Acked-by: Al Viro
Signed-off-by: Jens Axboe
25 Oct, 2013
1 commit
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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
Alexander Gordeev
Christoph Hellwig
Mike Christie
Matias Bjorling
Jeff MoyerAcked-by: Christoph Hellwig
Signed-off-by: Jens Axboe
01 Oct, 2013
1 commit
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Recently commit bab55417b10c ("block: support embedded device command
line partition") introduced CONFIG_CMDLINE_PARSER. However, that name
is too generic and sounds like it enables/disables generic kernel boot
arg processing, when it really is block specific.Before this option becomes a part of a full/final release, add the BLK_
prefix to it so that it is clear in absence of any other context that it
is block specific.In addition, fix up the following less critical items:
- help text was not really at all helpful.
- index file for Documentation was not updated
- add the new arg to Documentation/kernel-parameters.txt
- clarify wording in source commentsSigned-off-by: Paul Gortmaker
Cc: Jens Axboe
Cc: Cai Zhiyong
Cc: Wei Yongjun
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Sep, 2013
1 commit
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Read block device partition table from command line. The partition used
for fixed block device (eMMC) embedded device. It is no MBR, save
storage space. Bootloader can be easily accessed by absolute address of
data on the block device. Users can easily change the partition.This code reference MTD partition, source "drivers/mtd/cmdlinepart.c"
About the partition verbose reference
"Documentation/block/cmdline-partition.txt"[akpm@linux-foundation.org: fix printk text]
[yongjun_wei@trendmicro.com.cn: fix error return code in parse_parts()]
Signed-off-by: Cai Zhiyong
Cc: Karel Zak
Cc: "Wanglin (Albert)"
Cc: Marius Groeger
Cc: David Woodhouse
Cc: Jens Axboe
Cc: Brian Norris
Cc: Artem Bityutskiy
Signed-off-by: Wei Yongjun
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
04 Jan, 2012
2 commits
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Signed-off-by: Al Viro
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Signed-off-by: Al Viro
01 Aug, 2011
1 commit
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This moves the FC classes bsg code to the block layer and
makes it a lib so that other classes like iscsi and SAS can use it.It is helpful because working with the request queue, bios,
creating scatterlists, etc are a pain that the LLD does not
have to worry about with normal IOs and should not have to
worry about for bsg requests.Signed-off-by: Mike Christie
Signed-off-by: Jens Axboe
23 Oct, 2010
1 commit
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* 'for-2.6.37/barrier' of git://git.kernel.dk/linux-2.6-block: (46 commits)
xen-blkfront: disable barrier/flush write support
Added blk-lib.c and blk-barrier.c was renamed to blk-flush.c
block: remove BLKDEV_IFL_WAIT
aic7xxx_old: removed unused 'req' variable
block: remove the BH_Eopnotsupp flag
block: remove the BLKDEV_IFL_BARRIER flag
block: remove the WRITE_BARRIER flag
swap: do not send discards as barriers
fat: do not send discards as barriers
ext4: do not send discards as barriers
jbd2: replace barriers with explicit flush / FUA usage
jbd2: Modify ASYNC_COMMIT code to not rely on queue draining on barrier
jbd: replace barriers with explicit flush / FUA usage
nilfs2: replace barriers with explicit flush / FUA usage
reiserfs: replace barriers with explicit flush / FUA usage
gfs2: replace barriers with explicit flush / FUA usage
btrfs: replace barriers with explicit flush / FUA usage
xfs: replace barriers with explicit flush / FUA usage
block: pass gfp_mask and flags to sb_issue_discard
dm: convey that all flushes are processed as empty
...
16 Sep, 2010
1 commit
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o Actual implementation of throttling policy in block layer. Currently it
implements READ and WRITE bytes per second throttling logic. IOPS throttling
comes in later patches.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe
10 Sep, 2010
1 commit
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Without ordering requirements, barrier and ordering are minomers.
Rename block/blk-barrier.c to block/blk-flush.c. Rename of symbols
will follow.Signed-off-by: Tejun Heo
Cc: Christoph Hellwig
Signed-off-by: Jens Axboe
