44e44a1b32
This patch introduces a simple heuristic to load applications quickly,
and to perform the I/O requested by interactive applications just as
quickly. To this purpose, both a newly-created queue and a queue
associated with an interactive application (we explain in a moment how
BFQ decides whether the associated application is interactive),
receive the following two special treatments:
1) The weight of the queue is raised.
2) The queue unconditionally enjoys device idling when it empties; in
fact, if the requests of a queue are sync, then performing device
idling for the queue is a necessary condition to guarantee that the
queue receives a fraction of the throughput proportional to its weight
(see [1] for details).
For brevity, we call just weight-raising the combination of these
two preferential treatments. For a newly-created queue,
weight-raising starts immediately and lasts for a time interval that:
1) depends on the device speed and type (rotational or
non-rotational), and 2) is equal to the time needed to load (start up)
a large-size application on that device, with cold caches and with no
additional workload.
Finally, as for guaranteeing a fast execution to interactive,
I/O-related tasks (such as opening a file), consider that any
interactive application blocks and waits for user input both after
starting up and after executing some task. After a while, the user may
trigger new operations, after which the application stops again, and
so on. Accordingly, the low-latency heuristic weight-raises again a
queue in case it becomes backlogged after being idle for a
sufficiently long (configurable) time. The weight-raising then lasts
for the same time as for a just-created queue.
According to our experiments, the combination of this low-latency
heuristic and of the improvements described in the previous patch
allows BFQ to guarantee a high application responsiveness.
[1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O
Scheduler", Proceedings of the First Workshop on Mobile System
Technologies (MST-2015), May 2015.
http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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| .. | ||
| ABI | ||
| DocBook | ||
| EDID | ||
| PCI | ||
| RCU | ||
| accounting | ||
| acpi | ||
| admin-guide | ||
| aoe | ||
| arm | ||
| arm64 | ||
| auxdisplay | ||
| backlight | ||
| blackfin | ||
| block | ||
| blockdev | ||
| bus-devices | ||
| cdrom | ||
| cgroup-v1 | ||
| cma | ||
| connector | ||
| console | ||
| core-api | ||
| cpu-freq | ||
| cpuidle | ||
| cris | ||
| crypto | ||
| dev-tools | ||
| device-mapper | ||
| devicetree | ||
| dmaengine | ||
| doc-guide | ||
| driver-api | ||
| driver-model | ||
| early-userspace | ||
| extcon | ||
| fault-injection | ||
| fb | ||
| features | ||
| filesystems | ||
| firmware_class | ||
| fmc | ||
| fpga | ||
| frv | ||
| gpio | ||
| gpu | ||
| hid | ||
| hwmon | ||
| i2c | ||
| ia64 | ||
| ide | ||
| iio | ||
| infiniband | ||
| input | ||
| ioctl | ||
| isdn | ||
| kbuild | ||
| kdump | ||
| laptops | ||
| leds | ||
| lightnvm | ||
| livepatch | ||
| locking | ||
| m68k | ||
| md | ||
| media | ||
| memory-devices | ||
| metag | ||
| mic | ||
| mips | ||
| misc-devices | ||
| mmc | ||
| mn10300 | ||
| mtd | ||
| namespaces | ||
| netlabel | ||
| networking | ||
| nfc | ||
| nios2 | ||
| nvdimm | ||
| nvmem | ||
| parisc | ||
| pcmcia | ||
| perf | ||
| phy | ||
| platform | ||
| power | ||
| powerpc | ||
| pps | ||
| prctl | ||
| process | ||
| pti | ||
| ptp | ||
| rapidio | ||
| s390 | ||
| scheduler | ||
| scsi | ||
| security | ||
| serial | ||
| sh | ||
| sound | ||
| sparc | ||
| sphinx | ||
| sphinx-static | ||
| spi | ||
| sysctl | ||
| target | ||
| thermal | ||
| timers | ||
| trace | ||
| translations | ||
| usb | ||
| virtual | ||
| vm | ||
| w1 | ||
| watchdog | ||
| wimax | ||
| x86 | ||
| xtensa | ||
| .gitignore | ||
| 00-INDEX | ||
| Changes | ||
| CodingStyle | ||
| DMA-API-HOWTO.txt | ||
| DMA-API.txt | ||
| DMA-ISA-LPC.txt | ||
| DMA-attributes.txt | ||
| IPMI.txt | ||
| IRQ-affinity.txt | ||
| IRQ-domain.txt | ||
| IRQ.txt | ||
| Intel-IOMMU.txt | ||
| Makefile | ||
| Makefile.sphinx | ||
| SAK.txt | ||
| SM501.txt | ||
| SubmittingPatches | ||
| bcache.txt | ||
| bt8xxgpio.txt | ||
| btmrvl.txt | ||
| bus-virt-phys-mapping.txt | ||
| cachetlb.txt | ||
| cgroup-v2.txt | ||
| circular-buffers.txt | ||
| clk.txt | ||
| conf.py | ||
| cpu-load.txt | ||
| cputopology.txt | ||
| crc32.txt | ||
| dcdbas.txt | ||
| debugging-modules.txt | ||
| debugging-via-ohci1394.txt | ||
| dell_rbu.txt | ||
| digsig.txt | ||
| docutils.conf | ||
| dontdiff | ||
| efi-stub.txt | ||
| eisa.txt | ||
| flexible-arrays.txt | ||
| futex-requeue-pi.txt | ||
| gcc-plugins.txt | ||
| highuid.txt | ||
| hw_random.txt | ||
| hwspinlock.txt | ||
| index.rst | ||
| intel_txt.txt | ||
| io-mapping.txt | ||
| io_ordering.txt | ||
| iostats.txt | ||
| irqflags-tracing.txt | ||
| isa.txt | ||
| isapnp.txt | ||
| kernel-doc-nano-HOWTO.txt | ||
| kernel-per-CPU-kthreads.txt | ||
| kobject.txt | ||
| kprobes.txt | ||
| kref.txt | ||
| kselftest.txt | ||
| ldm.txt | ||
| lockup-watchdogs.txt | ||
| logo.gif | ||
| logo.txt | ||
| lzo.txt | ||
| mailbox.txt | ||
| memory-barriers.txt | ||
| memory-hotplug.txt | ||
| men-chameleon-bus.txt | ||
| nommu-mmap.txt | ||
| ntb.txt | ||
| numastat.txt | ||
| padata.txt | ||
| parport-lowlevel.txt | ||
| percpu-rw-semaphore.txt | ||
| phy.txt | ||
| pi-futex.txt | ||
| pinctrl.txt | ||
| pnp.txt | ||
| preempt-locking.txt | ||
| printk-formats.txt | ||
| pwm.txt | ||
| rbtree.txt | ||
| remoteproc.txt | ||
| rfkill.txt | ||
| robust-futex-ABI.txt | ||
| robust-futexes.txt | ||
| rpmsg.txt | ||
| rtc.txt | ||
| sgi-ioc4.txt | ||
| siphash.txt | ||
| smsc_ece1099.txt | ||
| static-keys.txt | ||
| svga.txt | ||
| sync_file.txt | ||
| this_cpu_ops.txt | ||
| unaligned-memory-access.txt | ||
| unshare.txt | ||
| vfio-mediated-device.txt | ||
| vfio.txt | ||
| video-output.txt | ||
| xillybus.txt | ||
| xz.txt | ||
| zorro.txt | ||
