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Qais Yousef d77530a1d4 sched/uclamp: Set max_spare_cap_cpu even if max_spare_cap is 0 
[ Upstream commit 6b00a40147 ]

When uclamp_max is being used, the util of the task could be higher than
the spare capacity of the CPU, but due to uclamp_max value we force-fit
it there.

The way the condition for checking for max_spare_cap in
find_energy_efficient_cpu() was constructed; it ignored any CPU that has
its spare_cap less than or _equal_ to max_spare_cap. Since we initialize
max_spare_cap to 0; this lead to never setting max_spare_cap_cpu and
hence ending up never performing compute_energy() for this cluster and
missing an opportunity for a better energy efficient placement to honour
uclamp_max setting.

	max_spare_cap = 0;
	cpu_cap = capacity_of(cpu) - cpu_util(p);  // 0 if cpu_util(p) is high

	...

	util_fits_cpu(...);		// will return true if uclamp_max forces it to fit

	...

	// this logic will fail to update max_spare_cap_cpu if cpu_cap is 0
	if (cpu_cap > max_spare_cap) {
		max_spare_cap = cpu_cap;
		max_spare_cap_cpu = cpu;
	}

prev_spare_cap suffers from a similar problem.

Fix the logic by converting the variables into long and treating -1
value as 'not populated' instead of 0 which is a viable and correct
spare capacity value. We need to be careful signed comparison is used
when comparing with cpu_cap in one of the conditions.

Fixes: 1d42509e47 ("sched/fair: Make EAS wakeup placement consider uclamp restrictions")
Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230916232955.2099394-2-qyousef@layalina.io
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-11-20 11:51:49 +01:00
arch iov_iter, x86: Be consistent about the __user tag on copy_mc_to_user() 2023-11-20 11:51:49 +01:00
block blk-throttle: check for overflow in calculate_bytes_allowed 2023-11-02 09:35:29 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: lrw,xts - Replace strlcpy with strscpy 2023-09-23 11:11:01 +02:00
Documentation dt-bindings: mmc: sdhci-msm: correct minimum number of clocks 2023-10-25 12:03:13 +02:00
drivers hwmon: (nct6775) Fix incorrect variable reuse in fan_div calculation 2023-11-20 11:51:49 +01:00
fs ceph_wait_on_conflict_unlink(): grab reference before dropping ->d_lock 2023-11-08 14:11:02 +01:00
include PCI: Prevent xHCI driver from claiming AMD VanGogh USB3 DRD device 2023-11-08 14:11:03 +01:00
init sched/psi: Select KERNFS as needed 2023-09-13 09:42:28 +02:00
io_uring io_uring: kiocb_done() should *not* trust ->ki_pos if ->{read,write}_iter() failed 2023-11-08 14:11:02 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel sched/uclamp: Set max_spare_cap_cpu even if max_spare_cap is 0 2023-11-20 11:51:49 +01:00
lib maple_tree: add GFP_KERNEL to allocations in mas_expected_entries() 2023-11-02 09:35:24 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mmap: fix error paths with dup_anon_vma() 2023-11-08 14:11:03 +01:00
net netfilter: nf_tables: audit log object reset once per table 2023-11-08 14:11:01 +01:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples fprobe: Pass entry_data to handlers 2023-10-25 12:03:12 +02:00
scripts kallsyms: Reduce the memory occupied by kallsyms_seqs_of_names[] 2023-10-25 12:03:16 +02:00
security KEYS: trusted: Remove redundant static calls usage 2023-10-19 23:08:50 +02:00
sound ASoC: SOF: sof-pci-dev: Fix community key quirk detection 2023-11-08 14:11:05 +01:00
tools perf evlist: Avoid frequency mode for the dummy event 2023-11-08 14:11:02 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.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 MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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 devlink: move code to a dedicated directory 2023-08-30 16:11:00 +02:00
Makefile Linux 6.1.62 2023-11-08 14:11:05 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.