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Angelo Ruocco 1be6e8a964 block, bfq: check low_latency flag in bfq_bfqq_save_state()
A just-created bfq_queue will certainly be deemed as interactive on
the arrival of its first I/O request, if the low_latency flag is
set. Yet, if the queue is merged with another queue on the arrival of
its first I/O request, it will not have the chance to be flagged as
interactive. Nevertheless, if the queue is then split soon enough, it
has to be flagged as interactive after the split.

To handle this early-merge scenario correctly, BFQ saves the state of
the queue, on the merge, as if the latter had already been deemed
interactive. So, if the queue is split soon, it will get
weight-raised, because the previous state of the queue is resumed on
the split.

Unfortunately, in the act of saving the state of the newly-created
queue, BFQ doesn't check whether the low_latency flag is set, and this
causes early-merged queues to be then weight-raised, on queue splits,
even if low_latency is off. This commit addresses this problem by
adding the missing check.

Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05 09:26:08 -07:00
arch Revert "mm: replace p??_write with pte_access_permitted in fault + gup paths" 2017-12-15 18:53:22 -08:00
block block, bfq: check low_latency flag in bfq_bfqq_save_state() 2018-01-05 09:26:08 -07:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-12-11 16:32:45 -08:00
Documentation Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs 2017-12-15 12:46:48 -08:00
drivers pktcdvd: Fix a recently introduced NULL pointer dereference 2018-01-05 09:03:04 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Revert "exec: avoid RLIMIT_STACK races with prlimit()" 2017-12-17 14:26:25 -08:00
include block: introduce zoned block devices zone write locking 2018-01-05 09:22:17 -07:00
init main: kernel_start: move housekeeping_init() before workqueue_init_early() 2017-11-27 08:56:57 -08:00
ipc Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-12-17 13:48:50 -08:00
lib blk-mq: improve heavily contended tag case 2017-12-22 11:09:37 -07:00
mm Revert "mm: replace p??_write with pte_access_permitted in fault + gup paths" 2017-12-15 18:53:22 -08:00
net NFS client fixes for Linux 4.15-rc4 2017-12-16 13:12:53 -08:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2017-12-03 13:08:30 -05:00
scripts Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-12-15 11:44:59 -08:00
security KEYS: reject NULL restriction string when type is specified 2017-12-08 15:13:29 +00:00
sound sound fixes for 4.15-rc3 2017-12-06 10:49:14 -08:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-12-15 13:08:37 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: x86: fix APIC page invalidation 2017-12-06 16:10:34 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild misc updates for v4.15 2017-11-17 17:51:33 -08:00
.mailmap Add Jason Gunthorpe as co-maintainer of the RDMA stack 2017-11-17 09:36:18 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-12-15 13:08:37 -08:00
Makefile Linux 4.15-rc4 2017-12-17 18:59:59 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.