This optional patch adds a fork/exit rate measurement facility using task watchers. It is intended to be a tool for measuring the impact of task watchers on fork and exit-heavy workloads. Signed-off-by: Matt Helsley --- kernel/Makefile | 1 kernel/twbench.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ lib/Kconfig.debug | 12 ++++++ 3 files changed, 116 insertions(+) Index: linux-2.6.18-mm1/kernel/twbench.c =================================================================== --- /dev/null +++ linux-2.6.18-mm1/kernel/twbench.c @@ -0,0 +1,103 @@ +#include +#include +#include + +#include +#include +#include + +#include +#include + +struct twb_counter { + atomic_t count; + u64 reset_time_ns; +}; + +static u64 read_reset_rate(void *p) +{ + u64 rate, ts_ns; + struct timespec ts; + struct twb_counter *ctr = p; + + /* begin pseudo-atomic region */ + preempt_disable(); + rate = atomic_xchg(((atomic_t*)&ctr->count), 0); + ktime_get_ts(&ts); + preempt_enable(); + /* end pseudo-atomic region */ + + ts_ns = timespec_to_ns(&ts); + rate *= NSEC_PER_SEC; + do_div(rate, (u32)(ts_ns - ctr->reset_time_ns)); + ctr->reset_time_ns = ts_ns; + return rate; +} + +/* Counter bits */ +static struct twb_counter num_clones; +static struct twb_counter num_exits; + +#ifndef MODULE +static int inc_clone(unsigned long val, struct task_struct *task) +{ + atomic_inc(&num_clones.count); + return 0; +} +task_watcher_func(clone, inc_clone); + +static int inc_exit(unsigned long val, struct task_struct *task) +{ + atomic_inc(&num_exits.count); + return 0; +} +task_watcher_func(exit, inc_exit); +#endif + +/* Debugfs bits */ +static struct dentry *twb_root, *twb_clone_file, *twb_exit_file; + +/* + * NOTE: Because open doesn't reset the count nor the reset time, + * userspace must discard the first values read before starting + * to monitor the rates. + */ +DEFINE_SIMPLE_ATTRIBUTE(rrr, read_reset_rate, NULL, "%llu\n"); + +static int __init twb_debugfs_init(void) +{ + twb_root = debugfs_create_dir("twbench", NULL); + if (!twb_root) + return -ENOMEM; + twb_clone_file = debugfs_create_file("clones", 0744, twb_root, + &num_clones, &rrr); + twb_exit_file = debugfs_create_file("exits", 0744, twb_root, + &num_exits, &rrr); + return 0; +} +#ifndef MODULE +__initcall(twb_debugfs_init); +#endif + +static void __exit twb_debugfs_exit(void) +{ + debugfs_remove(twb_clone_file); + debugfs_remove(twb_exit_file); + debugfs_remove(twb_root); +} + +static int __init twb_mod_init(void) +{ + int ret; + + ret = twb_debugfs_init(); + return ret; +} + +static void __exit twb_mod_exit(void) +{ + twb_debugfs_exit(); +} + +module_init(twb_mod_init); +module_exit(twb_mod_exit); Index: linux-2.6.18-mm1/lib/Kconfig.debug =================================================================== --- linux-2.6.18-mm1.orig/lib/Kconfig.debug +++ linux-2.6.18-mm1/lib/Kconfig.debug @@ -443,10 +443,22 @@ config RCU_TORTURE_TEST Say Y here if you want RCU torture tests to start automatically at boot time (you probably don't). Say M if you want the RCU torture tests to build as a module. Say N if you are unsure. +config TWBENCH + bool "Output fork/clone and exit rates" + depends on DEBUG_KERNEL && DEBUG_FS + default n + help + Print out the rate at which the system is fork/cloning new + processes to /twbench/clone + Print out the rate at which the system is exitting existing + processes to /twbench/exit + + If unsure, say N. + config LKDTM tristate "Linux Kernel Dump Test Tool Module" depends on KPROBES default n help Index: linux-2.6.18-mm1/kernel/Makefile =================================================================== --- linux-2.6.18-mm1.orig/kernel/Makefile +++ linux-2.6.18-mm1/kernel/Makefile @@ -45,10 +45,11 @@ obj-$(CONFIG_KPROBES) += kprobes.o obj-$(CONFIG_SYSFS) += ksysfs.o obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ obj-$(CONFIG_SECCOMP) += seccomp.o obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o +obj-$(CONFIG_TWBENCH) += twbench.o obj-$(CONFIG_DEBUG_SYNCHRO_TEST) += synchro-test.o obj-$(CONFIG_RELAY) += relay.o obj-$(CONFIG_UTS_NS) += utsname.o obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o -- - 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/