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Filename Latest commit message Latest commit date
Paolo Valente ac8b0cb415 block, bfq: do not plug I/O of in-service queue when harmful
If the in-service bfq_queue is sync and remains temporarily idle, then
I/O dispatching (from other queues) may be plugged. It may be dome for
two reasons: either to boost throughput, or to preserve the bandwidth
share of the in-service queue. In the first case, if the I/O of the
in-service queue, when it finally arrives, consists only of one small
I/O request, then it makes sense to plug even the I/O of the in-service
queue. In fact, serving such a small request immediately is likely to
lower throughput instead of boosting it, whereas waiting a little bit is
likely to let that request grow, thanks to request merging, and become
more profitable in terms of throughput (this is likely to happen exactly
because the I/O of the queue has been detected to boost throughput).

On the opposite end, if I/O dispatching is being plugged only to
preserve the bandwidth of the in-service queue, then it would be better
not to plug also the I/O of the in-service queue, because such a
plugging is likely to cause only loss of bandwidth for the queue.

Unfortunately, no distinction is made between the two cases, and the I/O
of the in-service queue is always plugged in case just a small I/O
request arrives. This commit draws this missing distinction and does not
perform harmful plugging.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-01-31 12:50:23 -07:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-01-27 12:02:00 -08:00
block block, bfq: do not plug I/O of in-service queue when harmful 2019-01-31 12:50:23 -07:00
certs
crypto crypto: sm3 - fix undefined shift by >= width of value 2019-01-10 21:37:32 +08:00
Documentation drm fixes. msm, sun4i, amdgpu, i915 gvt 2019-01-25 12:19:10 +13:00
drivers mtip32xx: ѕtop abusing the managed resource APIs 2019-01-31 12:50:12 -07:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs a set of small smb3 fixes, some fixing various crediting issues discovered during xfstest runs, five for stable 2019-01-26 15:38:22 -08:00
include Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-01-27 11:52:50 -08:00
init kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7 2019-01-14 10:37:09 +09:00
ipc
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-01-27 11:55:06 -08:00
lib XArray updates for 5.0-rc3 2019-01-22 17:08:30 +13:00
LICENSES
mm for-linus-20190125 2019-01-26 12:42:41 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-27 08:59:12 -08:00
samples samples/bpf: workaround clang asm goto compilation errors 2019-01-15 20:57:30 +01:00
scripts Bug fixes for gcc-plugins 2019-01-21 13:07:03 +13:00
security Merge branch 'fixes-v5.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-01-17 16:54:58 +12:00
sound sound fixes for 5.0-rc4 2019-01-25 05:55:26 +13:00
tools Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-01-27 12:02:00 -08:00
usr
virt KVM: validate userspace input in kvm_clear_dirty_log_protect() 2019-01-11 18:38:07 +01:00
.clang-format clang-format: Update .clang-format with the latest for_each macro list 2019-01-19 19:26:06 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-27 08:59:12 -08:00
Makefile Linux 5.0-rc4 2019-01-27 15:18:05 -08:00
README

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.