kernel_samsung_sm7125

jenna

Paolo Valente 80294c3bbf block, bfq: make lookup_next_entity push up vtime on expirations To provide a very smooth service, bfq starts to serve a bfq_queue only if the queue is 'eligible', i.e., if the same queue would have started to be served in the ideal, perfectly fair system that bfq simulates internally. This is obtained by associating each queue with a virtual start time, and by computing a special system virtual time quantity: a queue is eligible only if the system virtual time has reached the virtual start time of the queue. Finally, bfq guarantees that, when a new queue must be set in service, there is always at least one eligible entity for each active parent entity in the scheduler. To provide this guarantee, the function __bfq_lookup_next_entity pushes up, for each parent entity on which it is invoked, the system virtual time to the minimum among the virtual start times of the entities in the active tree for the parent entity (more precisely, the push up occurs if the system virtual time happens to be lower than all such virtual start times). There is however a circumstance in which __bfq_lookup_next_entity cannot push up the system virtual time for a parent entity, even if the system virtual time is lower than the virtual start times of all the child entities in the active tree. It happens if one of the child entities is in service. In fact, in such a case, there is already an eligible entity, the in-service one, even if it may not be not present in the active tree (because in-service entities may be removed from the active tree). Unfortunately, in the last re-design of the hierarchical-scheduling engine, the reset of the pointer to the in-service entity for a given parent entity--reset to be done as a consequence of the expiration of the in-service entity--always happens after the function __bfq_lookup_next_entity has been invoked. This causes the function to think that there is still an entity in service for the parent entity, and then that the system virtual time cannot be pushed up, even if actually such a no-more-in-service entity has already been properly reinserted into the active tree (or in some other tree if no more active). Yet, the system virtual time had to be pushed up, to be ready to correctly choose the next queue to serve. Because of the lack of this push up, bfq may wrongly set in service a queue that had been speculatively pre-computed as the possible next-in-service queue, but that would no more be the one to serve after the expiration and the reinsertion into the active trees of the previously in-service entities. This commit addresses this issue by making __bfq_lookup_next_entity properly push up the system virtual time if an expiration is occurring. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Tested-by: Lee Tibbert <lee.tibbert@gmail.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Jens Axboe <axboe@kernel.dk>		7 years ago
Documentation	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	7 years ago
arch	Linux 4.13-rc7	7 years ago
block	block, bfq: make lookup_next_entity push up vtime on expirations	7 years ago
certs	modsign: add markers to endif-statements in certs/Makefile	8 years ago
crypto	crypto: authencesn - Fix digest_null crash	8 years ago
drivers	nvme: don't blindly overwrite identifiers on disk revalidate	7 years ago
firmware	…
fs	Linux 4.13-rc7	7 years ago
include	string.h: add memcpy_and_pad()	7 years ago
init	random: do not ignore early device randomness	8 years ago
ipc	ipc: add missing container_of()s for randstruct	8 years ago
kernel	Linux 4.13-rc7	7 years ago
lib	kernel/watchdog: Prevent false positives with turbo modes	7 years ago
mm	Linux 4.13-rc7	7 years ago
net	Two nfsd bugfixes, neither 4.13 regressions, but both potentially	7 years ago
samples	samples/bpf: fix bpf tunnel cleanup	8 years ago
scripts	Kbuild fixes for v4.13	7 years ago
security	Now that IPC and other changes have landed, enable manual markings for	8 years ago
sound	ASoC: rt5677: Reintroduce I2C device IDs	7 years ago
tools	NTB bug fixes to address an incorrect ntb_mw_count reference in the NTB	7 years ago
usr	ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk.	8 years ago
virt	KVM/ARM Fixes for v4.13-rc4	8 years ago
.cocciconfig	…
.get_maintainer.ignore	…
.gitattributes	…
.gitignore	…
.mailmap	…
COPYING	…
CREDITS	…
Kbuild	…
Kconfig	…
MAINTAINERS	Linux 4.13-rc7	7 years ago
Makefile	Linux 4.13-rc7	7 years ago
README	…

README

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.