/* * netsniff-ng - the packet sniffing beast * Copyright 2009, 2010 Daniel Borkmann. * Copyright 2010 Marek Polacek. * Subject to the GPL, version 2. */ #include #include "iosched.h" #include "die.h" #define IOPRIO_CLASS_SHIFT 13 enum { ioprio_class_none, ioprio_class_rt, ioprio_class_be, ioprio_class_idle, }; enum { ioprio_who_process = 1, ioprio_who_pgrp, ioprio_who_user, }; static const char *const to_prio[] = { "none", "realtime", "best-effort", "idle", }; static inline int ioprio_set(int which, int who, int ioprio) { return syscall(SYS_ioprio_set, which, who, ioprio); } static inline int ioprio_get(int which, int who) { return syscall(SYS_ioprio_get, which, who); } static void ioprio_setpid(pid_t pid, int ioprio, int ioclass) { int ret = ioprio_set(ioprio_who_process, pid, ioprio | ioclass << IOPRIO_CLASS_SHIFT); if (ret < 0) panic("Failed to set io prio for pid: %s\n", strerror(errno)); } void ioprio_print(void) { int ioprio = ioprio_get(ioprio_who_process, getpid()); if (ioprio < 0) panic("Failed to fetch io prio for pid!\n"); else { int ioclass = ioprio >> IOPRIO_CLASS_SHIFT; if (ioclass != ioprio_class_idle) { ioprio &= 0xff; printf("%s: prio %d\n", to_prio[ioclass], ioprio); } else printf("%s\n", to_prio[ioclass]); } } void set_ioprio_rt(void) { ioprio_setpid(getpid(), 4, ioprio_class_rt); } void set_ioprio_be(void) { ioprio_setpid(getpid(), 4, ioprio_class_be); } r> net-next plumbingsTobias Klauser
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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-06-27 23:47:15 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-06-27 23:47:15 +0200
commit5ab666e09541e64ce2fd73411c3b5b9e4ad334b1 (patch)
treea27fca471605ace51d24ee8a50619c9523e37250 /Documentation/hwmon/tmp401
parent4c2e07c6a29e0129e975727b9f57eede813eea85 (diff)
intel_pstate: Do not clear utilization update hooks on policy changes
intel_pstate_set_policy() is invoked by the cpufreq core during driver initialization, on changes of policy attributes (minimim and maximum frequency, for example) via sysfs and via CPU notifications from the platform firmware. On some platforms the latter may occur relatively often. Commit bb6ab52f2bef (intel_pstate: Do not set utilization update hook too early) made intel_pstate_set_policy() clear the CPU's utilization update hook before updating the policy attributes for it (and set the hook again after doind that), but that involves invoking synchronize_sched() and adds overhead to the CPU notifications mentioned above and to the sched-RCU handling in general. That extra overhead is arguably not necessary, because updating policy attributes when the CPU's utilization update hook is active should not lead to any adverse effects, so drop the clearing of the hook from intel_pstate_set_policy() and make it check if the hook has been set already when attempting to set it. Fixes: bb6ab52f2bef (intel_pstate: Do not set utilization update hook too early) Reported-by: Jisheng Zhang <jszhang@marvell.com> Tested-by: Jisheng Zhang <jszhang@marvell.com> Tested-by: Doug Smythies <dsmythies@telus.net> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/hwmon/tmp401')