Delete alot of remaining code in kernel/time/clocksource.c that is replaced with this patch. Removed the deprecated "clock" kernel parameter. Shifts some of the code around so that the time of day override happens inside kernel/timer.c. The biggest timeofday changes are in update_wall_time() and change_clocksource(). I removed the unconditional call to change_clocksource(), and replaced it with a single atomic check. The atomic is asserted only when a clock change is needed. update_callback is no longer driven from update_wall_time(). The fast path is now a single atomic check. Signed-Off-By: Daniel Walker --- include/linux/clocksource.h | 3 kernel/time/clocksource.c | 216 ++++++-------------------------------------- kernel/timer.c | 167 +++++++++++++++++++++++++++++----- 3 files changed, 178 insertions(+), 208 deletions(-) Index: linux-2.6.18/include/linux/clocksource.h =================================================================== --- linux-2.6.18.orig/include/linux/clocksource.h +++ linux-2.6.18/include/linux/clocksource.h @@ -205,7 +205,8 @@ static inline void clocksource_calculate /* used to install a new clocksource */ -extern struct clocksource *clocksource_get_next(void); +extern int clocksource_sysfs_register(struct sysdev_attribute*); +extern void clocksource_sysfs_unregister(struct sysdev_attribute*); extern int clocksource_register(struct clocksource*); extern void clocksource_rating_change(struct clocksource*); extern struct clocksource * clocksource_get_clock(char*); Index: linux-2.6.18/kernel/time/clocksource.c =================================================================== --- linux-2.6.18.orig/kernel/time/clocksource.c +++ linux-2.6.18/kernel/time/clocksource.c @@ -5,6 +5,8 @@ * * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) * + * Copyright (C) 2006 MontaVista Daniel Walker (dwalker@mvista.com) + * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or @@ -21,7 +23,6 @@ * * TODO WishList: * o Allow clocksource drivers to be unregistered - * o get rid of clocksource_jiffies extern */ #include @@ -29,45 +30,15 @@ #include #include -/* XXX - Would like a better way for initializing curr_clocksource */ -extern struct clocksource clocksource_jiffies; - /*[Clocksource internal variables]--------- - * curr_clocksource: - * currently selected clocksource. Initialized to clocksource_jiffies. - * next_clocksource: - * pending next selected clocksource. * clocksource_list: * priority list with the registered clocksources * clocksource_lock: - * protects manipulations to curr_clocksource and next_clocksource - * and the clocksource_list - * override_name: - * Name of the user-specified clocksource. + * protects manipulations to the clocksource_list */ -static struct clocksource *curr_clocksource = &clocksource_jiffies; -static struct clocksource *next_clocksource; -static struct list_head clocksource_list = LIST_HEAD_INIT(clocksource_list); +static __read_mostly +struct list_head clocksource_list = LIST_HEAD_INIT(clocksource_list); static DEFINE_SPINLOCK(clocksource_lock); -static char override_name[32]; - -/** - * clocksource_get_next - Returns the selected clocksource - * - */ -struct clocksource *clocksource_get_next(void) -{ - unsigned long flags; - - spin_lock_irqsave(&clocksource_lock, flags); - if (next_clocksource) { - curr_clocksource = next_clocksource; - next_clocksource = NULL; - } - spin_unlock_irqrestore(&clocksource_lock, flags); - - return curr_clocksource; -} /** * __is_registered - Returns a clocksource if it's registered @@ -95,28 +66,6 @@ static struct clocksource * __is_registe } /** - * __get_clock - Finds a specific clocksource - * @name: name of the clocksource to return - * - * Private function. Must hold clocksource_lock when called. - * - * Returns the clocksource if registered, zero otherwise. - * If the @name is null the highest rated clock is returned. - */ -static inline struct clocksource * __get_clock(char * name) -{ - - if (unlikely(list_empty(&clocksource_list))) - return &clocksource_jiffies; - - if (!name) - return list_entry(clocksource_list.next, - struct clocksource, list); - - return __is_registered(name); -} - -/** * clocksource_get_clock - Finds a specific clocksource * @name: name of the clocksource to return * @@ -128,29 +77,17 @@ struct clocksource * clocksource_get_clo unsigned long flags; spin_lock_irqsave(&clocksource_lock, flags); - ret = __get_clock(name); + if (unlikely(list_empty(&clocksource_list))) + ret = &clocksource_jiffies; + else if (!name) + ret = list_entry(clocksource_list.next, + struct clocksource, list); + else + ret = __is_registered(name); spin_unlock_irqrestore(&clocksource_lock, flags); return ret; } - -/** - * select_clocksource - Finds the best registered clocksource. - * - * Private function. Must hold clocksource_lock when called. - * - * Looks through the list of registered clocksources, returning - * the one with the highest rating value. If there is a clocksource - * name that matches the override string, it returns that clocksource. - */ -static struct clocksource *select_clocksource(void) -{ - if (!*override_name) - return list_entry(clocksource_list.next, - struct clocksource, list); - - return __get_clock(override_name); -} /* * __sorted_list_add - Sorted clocksource add * @c: clocksource to add @@ -200,8 +137,6 @@ int clocksource_register(struct clocksou } else { INIT_LIST_HEAD(&c->list); __sorted_list_add(c); - /* scan the registered clocksources, and pick the best one */ - next_clocksource = select_clocksource(); } spin_unlock_irqrestore(&clocksource_lock, flags); return ret; @@ -230,70 +165,12 @@ void clocksource_rating_change(struct cl list_del_init(&c->list); __sorted_list_add(c); - next_clocksource = select_clocksource(); + /* XXX: Add block notifier to signal new rating */ spin_unlock_irqrestore(&clocksource_lock, flags); } EXPORT_SYMBOL(clocksource_rating_change); /** - * sysfs_show_current_clocksources - sysfs interface for current clocksource - * @dev: unused - * @buf: char buffer to be filled with clocksource list - * - * Provides sysfs interface for listing current clocksource. - */ -static ssize_t -sysfs_show_current_clocksources(struct sys_device *dev, char *buf) -{ - char *curr = buf; - - spin_lock_irq(&clocksource_lock); - curr += sprintf(curr, "%s ", curr_clocksource->name); - spin_unlock_irq(&clocksource_lock); - - curr += sprintf(curr, "\n"); - - return curr - buf; -} - -/** - * sysfs_override_clocksource - interface for manually overriding clocksource - * @dev: unused - * @buf: name of override clocksource - * @count: length of buffer - * - * Takes input from sysfs interface for manually overriding the default - * clocksource selction. - */ -static ssize_t sysfs_override_clocksource(struct sys_device *dev, - const char *buf, size_t count) -{ - size_t ret = count; - /* strings from sysfs write are not 0 terminated! */ - if (count >= sizeof(override_name)) - return -EINVAL; - - /* strip of \n: */ - if (buf[count-1] == '\n') - count--; - if (count < 1) - return -EINVAL; - - spin_lock_irq(&clocksource_lock); - - /* copy the name given: */ - memcpy(override_name, buf, count); - override_name[count] = 0; - - /* try to select it: */ - next_clocksource = select_clocksource(); - - spin_unlock_irq(&clocksource_lock); - - return ret; -} - -/** * sysfs_show_available_clocksources - sysfs interface for listing clocksource * @dev: unused * @buf: char buffer to be filled with clocksource list @@ -322,11 +199,8 @@ sysfs_show_available_clocksources(struct } /* - * Sysfs setup bits: + * Generic sysfs setup bits: */ -static SYSDEV_ATTR(current_clocksource, 0600, sysfs_show_current_clocksources, - sysfs_override_clocksource); - static SYSDEV_ATTR(available_clocksource, 0600, sysfs_show_available_clocksources, NULL); @@ -339,6 +213,21 @@ static struct sys_device device_clocksou .cls = &clocksource_sysclass, }; +/** + * clocksource_sysfs_register - interface to register a sysfs + * hook under the clocksource sys_device. + * @attr: sysdev_attribute created with the SYSDEV_ATTR macro. + * + * This functions should be used to create a sysfs file under + * the clocksource directory which will be used to show the current + * clock used by the code calling clocksource_sysfs_register(), and + * set a specific overide when written to. + */ +int clocksource_sysfs_register(struct sysdev_attribute * attr) +{ + return sysdev_create_file(&device_clocksource, attr); +} + static int __init init_clocksource_sysfs(void) { int error = sysdev_class_register(&clocksource_sysclass); @@ -348,52 +237,7 @@ static int __init init_clocksource_sysfs if (!error) error = sysdev_create_file( &device_clocksource, - &attr_current_clocksource); - if (!error) - error = sysdev_create_file( - &device_clocksource, &attr_available_clocksource); return error; } - -device_initcall(init_clocksource_sysfs); - -/** - * boot_override_clocksource - boot clock override - * @str: override name - * - * Takes a clocksource= boot argument and uses it - * as the clocksource override name. - */ -static int __init boot_override_clocksource(char* str) -{ - unsigned long flags; - spin_lock_irqsave(&clocksource_lock, flags); - if (str) - strlcpy(override_name, str, sizeof(override_name)); - spin_unlock_irqrestore(&clocksource_lock, flags); - return 1; -} - -__setup("clocksource=", boot_override_clocksource); - -/** - * boot_override_clock - Compatibility layer for deprecated boot option - * @str: override name - * - * DEPRECATED! Takes a clock= boot argument and uses it - * as the clocksource override name - */ -static int __init boot_override_clock(char* str) -{ - if (!strcmp(str, "pmtmr")) { - printk("Warning: clock=pmtmr is deprecated. " - "Use clocksource=acpi_pm.\n"); - return boot_override_clocksource("acpi_pm"); - } - printk("Warning! clock= boot option is deprecated. " - "Use clocksource=xyz\n"); - return boot_override_clocksource(str); -} - -__setup("clock=", boot_override_clock); +postcore_initcall(init_clocksource_sysfs); Index: linux-2.6.18/kernel/timer.c =================================================================== --- linux-2.6.18.orig/kernel/timer.c +++ linux-2.6.18/kernel/timer.c @@ -17,6 +17,8 @@ * 2000-10-05 Implemented scalable SMP per-CPU timer handling. * Copyright (C) 2000, 2001, 2002 Ingo Molnar * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar + * 2006-08-03 Added usage of the generic clocksource API + * Copyright (C) 2006 MontaVista, Daniel Walker */ #include @@ -578,9 +580,15 @@ EXPORT_SYMBOL(xtime); /* XXX - all of this timekeeping code should be later moved to time.c */ #include -static struct clocksource *clock; /* pointer to current clocksource */ +/* pointer to current clocksource */ +static struct clocksource *clock = &clocksource_jiffies; +static char clock_override_name[32]; + +/* Interrupt update singaling variables */ +static atomic_t clock_check = ATOMIC_INIT(0); #ifdef CONFIG_GENERIC_TIME + /** * __get_nsec_offset - Returns nanoseconds since last call to periodic_hook * @@ -700,29 +708,119 @@ EXPORT_SYMBOL(do_settimeofday); * * Accumulates current time interval and initializes new clocksource */ -static int change_clocksource(void) +static int change_clocksource(char * override) { - struct clocksource *new; - cycle_t now; u64 nsec; - new = clocksource_get_next(); - if (clock != new) { - now = clocksource_read(new); - nsec = __get_nsec_offset(); - timespec_add_ns(&xtime, nsec); - - clock = new; - clock->cycle_last = now; - printk(KERN_INFO "Time: %s clocksource has been installed.\n", - clock->name); - return 1; - } else if (clock->update_callback) { - return clock->update_callback(); + cycle_t now; + struct clocksource *new = clocksource_get_clock(override); + + now = clocksource_read(new); + nsec = __get_nsec_offset(); + timespec_add_ns(&xtime, nsec); + + clock = new; + clock->cycle_last = now; + printk(KERN_INFO "Time: %s clocksource has been installed.\n", + clock->name); + + return 1; +} + +/** + * sysfs_show_current_clocksources - sysfs interface for current clocksource + * @dev: unused + * @buf: char buffer to be filled with clocksource list + * + * Provides sysfs interface for listing the current clocksource. + * Locking handled inside sysfs. + */ +static ssize_t +sysfs_show_current_clocksources(struct sys_device *dev, char *buf) +{ + return sprintf(buf, "%s \n", clock->name); +} + +/** + * sysfs_override_clocksource - interface for manually overriding clocksource + * @dev: unused + * @buf: name of override clocksource + * @count: length of buffer + * + * Takes input from sysfs interface for manually overriding the default + * clocksource selction. Locking handled inside sysfs + */ +static ssize_t sysfs_override_clocksource(struct sys_device *dev, + const char *buf, size_t count) +{ + size_t ret = count; + + /* + * If there's already an update in progress then + * we can't proceed. + */ + if (atomic_read(&clock_check)) + return -EINVAL; + + /* strings from sysfs write are not 0 terminated! */ + if (count >= sizeof(clock_override_name)) + return -EINVAL; + + /* strip of \n: */ + if (buf[count-1] == '\n') + count--; + if (count < 1) + return -EINVAL; + + /* copy the name given: */ + memcpy(clock_override_name, buf, count); + clock_override_name[count] = 0; + + if (!clocksource_get_clock(clock_override_name)) { + clock_override_name[0] = 0; + return -EINVAL; } - return 0; + + atomic_inc(&clock_check); + + return ret; +} + +/* + * Sysfs atrribure structure. + */ +static SYSDEV_ATTR(timeofday_clocksource, 0600, sysfs_show_current_clocksources, + sysfs_override_clocksource); + +/** + * boot_override_clocksource - boot clock override + * @str: override name + * + * Takes a clocksource= boot argument and uses it + * as the clocksource override name. + */ +static int __init boot_override_clocksource(char* str) +{ + if (str) { + /* + * Make sure the clock exists. + */ + if (clocksource_get_clock(str)) + strlcpy(clock_override_name, str, + sizeof(clock_override_name)); + else { + printk("Time: requested clock \"%s\" doesn't exist\n", + str); + return 0; + } + + } + + return 1; } +__setup("timeofday_clocksource=", boot_override_clocksource); + #else -#define change_clocksource() do { 0; } while(0) +#define change_clocksource(x) do { } while(0) #endif /** @@ -754,7 +852,7 @@ void __init timekeeping_init(void) ntp_clear(); - clock = clocksource_get_next(); + clock = clocksource_get_best_clock(); clocksource_calculate_interval(clock, tick_nsec); clock->cycle_last = clocksource_read(clock); @@ -811,6 +909,17 @@ static int __init timekeeping_init_devic int error = sysdev_class_register(&timekeeping_sysclass); if (!error) error = sysdev_register(&device_timer); + +#ifdef CONFIG_GENERIC_TIME + clocksource_sysfs_register(&attr_timeofday_clocksource); + + /* + * All the clocks should be registered at this point, + * so it's safe to trigger a switch to a higher res + * clock. + */ + atomic_inc(&clock_check); +#endif return error; } @@ -952,10 +1061,26 @@ static void update_wall_time(void) clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift; /* check to see if there is a new clocksource to use */ - if (change_clocksource()) { + if (unlikely(atomic_read(&clock_check))) { + + /* + * Switch to the new override clock, or the highest + * rated clock. + */ + if (*clock_override_name) + change_clocksource(clock_override_name); + else + change_clocksource(NULL); + clock->error = 0; clock->xtime_nsec = 0; clocksource_calculate_interval(clock, tick_nsec); + + /* + * Remove the change signal + */ + atomic_dec(&clock_check); + } } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/