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Mete Durlu 367c50f784 s390/vtime: fix average steal time calculation
Current average steal timer calculation produces volatile and inflated
values. The only user of this value is KVM so far and it uses that to
decide whether or not to yield the vCPU which is seeing steal time.
KVM compares average steal timer to a threshold and if the threshold
is past then it does not allow CPU polling and yields it to host, else
it keeps the CPU by polling.
Since KVM's steal time threshold is very low by default (%10) it most
likely is not effected much by the bloated average steal timer values
because the operating region is pretty small. However there might be
new users in the future who might rely on this number. Fix average
steal timer calculation by changing the formula from:

	avg_steal_timer = avg_steal_timer / 2 + steal_timer;

to the following:

	avg_steal_timer = (avg_steal_timer + steal_timer) / 2;

This ensures that avg_steal_timer is actually a naive average of steal
timer values. It now closely follows steal timer values but of course
in a smoother manner.

Fixes: 152e9b8676 ("s390/vtime: steal time exponential moving average")
Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
History 2024-03-13 09:23:44 +01:00
arch s390/vtime: fix average steal time calculation 2024-03-13 09:23:44 +01:00
block Revert "dm: use queue_limits_set" 2024-03-11 17:11:28 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto crypto: lskcipher - Copy IV in lskcipher glue code always 2024-02-24 08:37:24 +08:00
Documentation slab changes for 6.9 2024-03-12 20:14:54 -07:00
drivers mm, slab: remove last vestiges of SLAB_MEM_SPREAD 2024-03-12 20:32:19 -07:00
fs mm, slab: remove last vestiges of SLAB_MEM_SPREAD 2024-03-12 20:32:19 -07:00
include printk changes for 6.9 2024-03-12 20:54:50 -07:00
init Networking changes for 6.9. 2024-03-12 17:44:08 -07:00
io_uring for-6.9/io_uring-20240310 2024-03-11 11:35:31 -07:00
ipc shm: Slim down dependencies 2023-12-20 19:26:31 -05:00
kernel printk changes for 6.9 2024-03-12 20:54:50 -07:00
lib printk changes for 6.9 2024-03-12 20:54:50 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm slab changes for 6.9 2024-03-12 20:14:54 -07:00
net mm, slab: remove last vestiges of SLAB_MEM_SPREAD 2024-03-12 20:32:19 -07:00
rust Networking changes for 6.9. 2024-03-12 17:44:08 -07:00
samples Networking changes for 6.9. 2024-03-12 17:44:08 -07:00
scripts Networking changes for 6.9. 2024-03-12 17:44:08 -07:00
security lsm/stable-6.9 PR 20240312 2024-03-12 20:03:34 -07:00
sound ASoC: Fixes for v6.8 2024-03-08 08:53:36 +01:00
tools slab changes for 6.9 2024-03-12 20:14:54 -07:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM: Make KVM_MEM_GUEST_MEMFD mutually exclusive with KVM_MEM_READONLY 2024-02-22 17:07:06 -08:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.mailmap Networking changes for 6.9. 2024-03-12 17:44:08 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS vfs-6.9.ntfs 2024-03-11 09:55:17 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking changes for 6.9. 2024-03-12 17:44:08 -07:00
Makefile Rust changes for v6.9 2024-03-11 12:31:28 -07:00
README README: Fix spelling/capitalization 2024-02-12 16:42:13 -07:00

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.