linux/drivers/base/cpu.c, branch v4.14

Revert "PM / QoS: Fix device resume latency PM QoS"

2017-10-31T17:35:40Z

This reverts commit 0cc2b4e5a020 (PM / QoS: Fix device resume latency PM QoS) as it introduced regressions on multiple systems and the fix-up in commit 2a9a86d5c813 (PM / QoS: Fix default runtime_pm device resume latency) does not address all of them. The original problem that commit 0cc2b4e5a020 was attempting to fix will be addressed later. Fixes: 0cc2b4e5a020 (PM / QoS: Fix device resume latency PM QoS) Reported-by: Geert Uytterhoeven Signed-off-by: Rafael J. Wysocki

PM / QoS: Fix device resume latency PM QoS

2017-10-24T13:20:45Z

The special value of 0 for device resume latency PM QoS means "no restriction", but there are two problems with that. First, device resume latency PM QoS requests with 0 as the value are always put in front of requests with positive values in the priority lists used internally by the PM QoS framework, causing 0 to be chosen as an effective constraint value. However, that 0 is then interpreted as "no restriction" effectively overriding the other requests with specific restrictions which is incorrect. Second, the users of device resume latency PM QoS have no way to specify that *any* resume latency at all should be avoided, which is an artificial limitation in general. To address these issues, modify device resume latency PM QoS to use S32_MAX as the "no constraint" value and 0 as the "no latency at all" one and rework its users (the cpuidle menu governor, the genpd QoS governor and the runtime PM framework) to follow these changes. Also add a special "n/a" value to the corresponding user space I/F to allow user space to indicate that it cannot accept any resume latencies at all for the given device. Fixes: 85dc0b8a4019 (PM / QoS: Make it possible to expose PM QoS latency constraints) Link: https://bugzilla.kernel.org/show_bug.cgi?id=197323 Reported-by: Reinette Chatre Tested-by: Reinette Chatre Signed-off-by: Rafael J. Wysocki Acked-by: Alex Shi Cc: All applicable

treewide: make "nr_cpu_ids" unsigned

2017-09-09T01:26:48Z

First, number of CPUs can't be negative number. Second, different signnnedness leads to suboptimal code in the following cases: 1) kmalloc(nr_cpu_ids * sizeof(X)); "int" has to be sign extended to size_t. 2) while (loff_t *pos < nr_cpu_ids) MOVSXD is 1 byte longed than the same MOV. Other cases exist as well. Basically compiler is told that nr_cpu_ids can't be negative which can't be deduced if it is "int". Code savings on allyesconfig kernel: -3KB add/remove: 0/0 grow/shrink: 25/264 up/down: 261/-3631 (-3370) function old new delta coretemp_cpu_online 450 512 +62 rcu_init_one 1234 1272 +38 pci_device_probe 374 399 +25 ... pgdat_reclaimable_pages 628 556 -72 select_fallback_rq 446 369 -77 task_numa_find_cpu 1923 1807 -116 Link: http://lkml.kernel.org/r/20170819114959.GA30580@avx2 Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

CPU / PM: expose pm_qos_resume_latency for CPUs

2017-01-30T10:05:29Z

The cpu-dma PM QoS constraint impacts all the cpus in the system. There is no way to let the user to choose a PM QoS constraint per cpu. The following patch exposes to the userspace a per cpu based sysfs file in order to let the userspace to change the value of the PM QoS latency constraint. This change is inoperative in its form and the cpuidle governors have to take into account the per cpu latency constraint in addition to the global cpu-dma latency constraint in order to operate properly. BTW The pm_qos_resume_latency usage defined in Documentation/ABI/testing/sysfs-devices-power The /sys/devices/.../power/pm_qos_resume_latency_us attribute contains the PM QoS resume latency limit for the given device, which is the maximum allowed time it can take to resume the device, after it has been suspended at run time, from a resume request to the moment the device will be ready to process I/O, in microseconds. If it is equal to 0, however, this means that the PM QoS resume latency may be arbitrary. Signed-off-by: Alex Shi Signed-off-by: Rafael J. Wysocki

cpu: clean up register_cpu func

2016-08-31T13:19:55Z

This patch could reduce one branch in this function. Also make the code more readble. Signed-off-by: Alex Shi Acked-by: Daniel Lezcano To: linux-kernel@vger.kernel.org To: Greg Kroah-Hartman Cc: linux-pm@vger.kernel.org Cc: Ulf Hansson Cc: Daniel Lezcano Signed-off-by: Greg Kroah-Hartman

drivers/base/cpu.c: use __cpu_*_mask directly

2016-01-21T01:09:18Z

The only user of the lvalue-ness of the cpu_*_mask variables is in drivers/base/cpu.c, and that is mostly a work-around for the fact that not even const variables can be used in static initialization. Now that the underlying struct cpumasks are exposed we can take their address. Signed-off-by: Rasmus Villemoes Acked-by: Rusty Russell Acked-by: Greg Kroah-Hartman Cc: Michael Ellerman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

cpu: Remove bogus __ref annotation of cpu_subsys_online()

2015-08-05T22:18:26Z

In commit 0db0628d9012 ("kernel: delete __cpuinit usage from all core kernel files") cpu_up() lost its __cpuinit annotation, vanishing the need for cpu_subsys_online() to have a __ref annotation. Just drop it to be able to catch real section mismatches in the future. Signed-off-by: Mathias Krause Cc: Paul Gortmaker Signed-off-by: Greg Kroah-Hartman

show nohz_full cpus in sysfs

2015-05-20T07:15:09Z

Currently there is no way to query which CPUs are in nohz_full mode from userspace. Export the CPU list running in nohz_full mode in sysfs, specifically in the file /sys/devices/system/cpu/nohz_full This can be used by system management tools like libvirt, openstack, and others to ensure proper task placement. Signed-off-by: Rik van Riel Acked-by: Mike Galbraith Acked-by: Chris Metcalf Signed-off-by: Greg Kroah-Hartman

show isolated cpus in sysfs

2015-05-20T07:15:06Z

After system bootup, there is no totally reliable way to see which CPUs are isolated, because the kernel may modify the CPUs specified on the isolcpus= kernel command line option. Export the CPU list that actually got isolated in sysfs, specifically in the file /sys/devices/system/cpu/isolated This can be used by system management tools like libvirt, openstack, and others to ensure proper placement of tasks. Suggested-by: Li Zefan Signed-off-by: Rik van Riel Acked-by: Mike Galbraith Acked-by: Chris Metcalf Signed-off-by: Greg Kroah-Hartman

drivers/base: use %*pb[l] to print bitmaps including cpumasks and nodemasks

2015-02-14T05:21:38Z

printk and friends can now format bitmaps using '%*pb[l]'. cpumask and nodemask also provide cpumask_pr_args() and nodemask_pr_args() respectively which can be used to generate the two printf arguments necessary to format the specified cpu/nodemask. * Line termination only requires one extra space at the end of the buffer. Use PAGE_SIZE - 1 instead of PAGE_SIZE - 2 when formatting. Signed-off-by: Tejun Heo Acked-by: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds