From: David Howells The attached patch adds a module for testing and benchmarking mutexes, semaphores and R/W semaphores. Using it is simple: insmod synchro-test.ko It will exit with error ENOANO after running the tests and printing the results to the kernel console log. The available arguments are: (*) mx=N Start up to N mutex thrashing threads, where N is at most 20. All will try and thrash the same mutex. (*) sm=N Start up to N counting semaphore thrashing threads, where N is at most 20. All will try and thrash the same semaphore. (*) ism=M Initialise the counting semaphore with M, where M is any positive integer greater than zero. The default is 4. (*) rd=N (*) wr=O (*) dg=P Start up to N reader thrashing threads, O writer thrashing threads and P downgrader thrashing threads, where N, O and P are at most 20 apiece. All will try and thrash the same read/write semaphore. (*) elapse=N Run the tests for N seconds. The default is 5. (*) load=N Each thread delays for N uS whilst holding the lock. The dfault is 0. (*) interval=N Each thread delays for N uS whilst not holding the lock. The default is 0. (*) do_sched=1 Each thread will call schedule if required after each iteration. (*) v=1 Print more verbose information, including a thread iteration distribution list. The module should be enabled by turning on CONFIG_DEBUG_SYNCHRO_TEST to "m". Signed-Off-By: David Howells Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton --- Documentation/synchro-test.txt | 59 +++ kernel/Makefile | 1 kernel/synchro-test.c | 527 +++++++++++++++++++++++++++++++ lib/Kconfig.debug | 14 4 files changed, 601 insertions(+) diff -puN /dev/null Documentation/synchro-test.txt --- /dev/null Thu Apr 11 07:25:15 2002 +++ 25-akpm/Documentation/synchro-test.txt Fri Jan 6 17:04:58 2006 @@ -0,0 +1,59 @@ +The synchro-test.ko module can be used for testing and benchmarking mutexes, +semaphores and R/W semaphores. + +The module is compiled by setting CONFIG_DEBUG_SYNCHRO_TEST to "m" when +configuring the kernel. + +Using it is simple: + + insmod synchro-test.ko + +It will exit with error ENOANO after running the tests and printing the +results to the kernel console log. + +The available arguments are: + + (*) mx=N + + Start up to N mutex thrashing threads, where N is at most 20. All will + try and thrash the same mutex. + + (*) sm=N + + Start up to N counting semaphore thrashing threads, where N is at most + 20. All will try and thrash the same semaphore. + + (*) ism=M + + Initialise the counting semaphore with M, where M is any positive + integer greater than zero. The default is 4. + + (*) rd=N + (*) wr=O + (*) dg=P + + Start up to N reader thrashing threads, O writer thrashing threads and + P downgrader thrashing threads, where N, O and P are at most 20 + apiece. All will try and thrash the same read/write semaphore. + + (*) elapse=N + + Run the tests for N seconds. The default is 5. + + (*) load=N + + Each thread delays for N uS whilst holding the lock. The default is 0. + + (*) interval=N + + Each thread delays for N uS whilst not holding the lock. The default + is 0. + + (*) do_sched=1 + + Each thread will call schedule if required after each iteration. + + (*) v=1 + + Print more verbose information, including a thread iteration + distribution list. diff -puN kernel/Makefile~mutex-subsystem-synchro-test-module kernel/Makefile --- 25/kernel/Makefile~mutex-subsystem-synchro-test-module Fri Jan 6 17:04:58 2006 +++ 25-akpm/kernel/Makefile Fri Jan 6 17:04:58 2006 @@ -33,6 +33,7 @@ obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_SECCOMP) += seccomp.o obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o +obj-$(CONFIG_DEBUG_SYNCHRO_TEST) += synchro-test.o ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y) # According to Alan Modra , the -fno-omit-frame-pointer is diff -puN /dev/null kernel/synchro-test.c --- /dev/null Thu Apr 11 07:25:15 2002 +++ 25-akpm/kernel/synchro-test.c Fri Jan 6 17:04:58 2006 @@ -0,0 +1,527 @@ +/* synchro-test.c: run some threads to test the synchronisation primitives + * + * Copyright (C) 2005, 2006 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.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 (at your option) any later version. + * + * The module should be run as something like: + * + * insmod synchro-test.ko rd=2 wr=2 + * insmod synchro-test.ko mx=1 + * insmod synchro-test.ko sm=2 ism=1 + * insmod synchro-test.ko sm=2 ism=2 + * + * See Documentation/synchro-test.txt for more information. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define MAX_THREADS 64 + +/* + * Turn on self-validation if we do a one-shot boot-time test: + */ +#ifndef MODULE +# define VALIDATE_OPERATORS +#endif + +static int nummx; +static int numsm, seminit = 4; +static int numrd, numwr, numdg; +static int elapse = 5, load, do_sched, interval; +static int verbose = 0; + +MODULE_AUTHOR("David Howells"); +MODULE_DESCRIPTION("Synchronisation primitive test demo"); +MODULE_LICENSE("GPL"); + +module_param_named(v, verbose, int, 0); +MODULE_PARM_DESC(verbose, "Verbosity"); + +module_param_named(mx, nummx, int, 0); +MODULE_PARM_DESC(nummx, "Number of mutex threads"); + +module_param_named(sm, numsm, int, 0); +MODULE_PARM_DESC(numsm, "Number of semaphore threads"); + +module_param_named(ism, seminit, int, 0); +MODULE_PARM_DESC(seminit, "Initial semaphore value"); + +module_param_named(rd, numrd, int, 0); +MODULE_PARM_DESC(numrd, "Number of reader threads"); + +module_param_named(wr, numwr, int, 0); +MODULE_PARM_DESC(numwr, "Number of writer threads"); + +module_param_named(dg, numdg, int, 0); +MODULE_PARM_DESC(numdg, "Number of downgrader threads"); + +module_param(elapse, int, 0); +MODULE_PARM_DESC(elapse, "Number of seconds to run for"); + +module_param(load, int, 0); +MODULE_PARM_DESC(load, "Length of load in uS"); + +module_param(interval, int, 0); +MODULE_PARM_DESC(interval, "Length of interval in uS before re-getting lock"); + +module_param(do_sched, int, 0); +MODULE_PARM_DESC(do_sched, "True if each thread should schedule regularly"); + +/* the semaphores under test */ +static struct mutex ____cacheline_aligned mutex; +static struct semaphore ____cacheline_aligned sem; +static struct rw_semaphore ____cacheline_aligned rwsem; + +static atomic_t ____cacheline_aligned do_stuff = ATOMIC_INIT(0); + +#ifdef VALIDATE_OPERATORS +static atomic_t ____cacheline_aligned mutexes = ATOMIC_INIT(0); +static atomic_t ____cacheline_aligned semaphores = ATOMIC_INIT(0); +static atomic_t ____cacheline_aligned readers = ATOMIC_INIT(0); +static atomic_t ____cacheline_aligned writers = ATOMIC_INIT(0); +#endif + +static unsigned int ____cacheline_aligned mutexes_taken [MAX_THREADS]; +static unsigned int ____cacheline_aligned semaphores_taken [MAX_THREADS]; +static unsigned int ____cacheline_aligned reads_taken [MAX_THREADS]; +static unsigned int ____cacheline_aligned writes_taken [MAX_THREADS]; +static unsigned int ____cacheline_aligned downgrades_taken [MAX_THREADS]; + +static struct completion ____cacheline_aligned mx_comp[MAX_THREADS]; +static struct completion ____cacheline_aligned sm_comp[MAX_THREADS]; +static struct completion ____cacheline_aligned rd_comp[MAX_THREADS]; +static struct completion ____cacheline_aligned wr_comp[MAX_THREADS]; +static struct completion ____cacheline_aligned dg_comp[MAX_THREADS]; + +static struct timer_list ____cacheline_aligned timer; + +#define ACCOUNT(var, N) var##_taken[N]++; + +#ifdef VALIDATE_OPERATORS +#define TRACK(var, dir) atomic_##dir(&(var)) + +#define CHECK(var, cond, val) \ +do { \ + int x = atomic_read(&(var)); \ + if (unlikely(!(x cond (val)))) \ + printk("check [%s %s %d, == %d] failed in %s\n", \ + #var, #cond, (val), x, __func__); \ +} while (0) + +#else +#define TRACK(var, dir) do {} while(0) +#define CHECK(var, cond, val) do {} while(0) +#endif + +static inline void do_mutex_lock(unsigned int N) +{ + mutex_lock(&mutex); + + ACCOUNT(mutexes, N); + TRACK(mutexes, inc); + CHECK(mutexes, ==, 1); +} + +static inline void do_mutex_unlock(unsigned int N) +{ + CHECK(mutexes, ==, 1); + TRACK(mutexes, dec); + + mutex_unlock(&mutex); +} + +static inline void do_down(unsigned int N) +{ + CHECK(mutexes, <, seminit); + + down(&sem); + + ACCOUNT(semaphores, N); + TRACK(semaphores, inc); +} + +static inline void do_up(unsigned int N) +{ + CHECK(semaphores, >, 0); + TRACK(semaphores, dec); + + up(&sem); +} + +static inline void do_down_read(unsigned int N) +{ + down_read(&rwsem); + + ACCOUNT(reads, N); + TRACK(readers, inc); + CHECK(readers, >, 0); + CHECK(writers, ==, 0); +} + +static inline void do_up_read(unsigned int N) +{ + CHECK(readers, >, 0); + CHECK(writers, ==, 0); + TRACK(readers, dec); + + up_read(&rwsem); +} + +static inline void do_down_write(unsigned int N) +{ + down_write(&rwsem); + + ACCOUNT(writes, N); + TRACK(writers, inc); + CHECK(writers, ==, 1); + CHECK(readers, ==, 0); +} + +static inline void do_up_write(unsigned int N) +{ + CHECK(writers, ==, 1); + CHECK(readers, ==, 0); + TRACK(writers, dec); + + up_write(&rwsem); +} + +static inline void do_downgrade_write(unsigned int N) +{ + CHECK(writers, ==, 1); + CHECK(readers, ==, 0); + TRACK(writers, dec); + TRACK(readers, inc); + + downgrade_write(&rwsem); + + ACCOUNT(downgrades, N); +} + +static inline void sched(void) +{ + if (do_sched) + schedule(); +} + +int mutexer(void *arg) +{ + unsigned int N = (unsigned long) arg; + + daemonize("Mutex%u", N); + set_user_nice(current, 19); + + while (atomic_read(&do_stuff)) { + do_mutex_lock(N); + if (load) + udelay(load); + do_mutex_unlock(N); + sched(); + if (interval) + udelay(interval); + } + + if (verbose >= 2) + printk("%s: done\n", current->comm); + complete_and_exit(&mx_comp[N], 0); +} + +int semaphorer(void *arg) +{ + unsigned int N = (unsigned long) arg; + + daemonize("Sem%u", N); + set_user_nice(current, 19); + + while (atomic_read(&do_stuff)) { + do_down(N); + if (load) + udelay(load); + do_up(N); + sched(); + if (interval) + udelay(interval); + } + + if (verbose >= 2) + printk("%s: done\n", current->comm); + complete_and_exit(&sm_comp[N], 0); +} + +int reader(void *arg) +{ + unsigned int N = (unsigned long) arg; + + daemonize("Read%u", N); + set_user_nice(current, 19); + + while (atomic_read(&do_stuff)) { + do_down_read(N); +#ifdef LOAD_TEST + if (load) + udelay(load); +#endif + do_up_read(N); + sched(); + if (interval) + udelay(interval); + } + + if (verbose >= 2) + printk("%s: done\n", current->comm); + complete_and_exit(&rd_comp[N], 0); +} + +int writer(void *arg) +{ + unsigned int N = (unsigned long) arg; + + daemonize("Write%u", N); + set_user_nice(current, 19); + + while (atomic_read(&do_stuff)) { + do_down_write(N); +#ifdef LOAD_TEST + if (load) + udelay(load); +#endif + do_up_write(N); + sched(); + if (interval) + udelay(interval); + } + + if (verbose >= 2) + printk("%s: done\n", current->comm); + complete_and_exit(&wr_comp[N], 0); +} + +int downgrader(void *arg) +{ + unsigned int N = (unsigned long) arg; + + daemonize("Down%u", N); + set_user_nice(current, 19); + + while (atomic_read(&do_stuff)) { + do_down_write(N); +#ifdef LOAD_TEST + if (load) + udelay(load); +#endif + do_downgrade_write(N); +#ifdef LOAD_TEST + if (load) + udelay(load); +#endif + do_up_read(N); + sched(); + if (interval) + udelay(interval); + } + + if (verbose >= 2) + printk("%s: done\n", current->comm); + complete_and_exit(&dg_comp[N], 0); +} + +static void stop_test(unsigned long dummy) +{ + atomic_set(&do_stuff, 0); +} + +static unsigned int total(const char *what, unsigned int counts[], int num) +{ + unsigned int tot = 0, max = 0, min = UINT_MAX, zeros = 0, cnt; + int loop; + + for (loop = 0; loop < num; loop++) { + cnt = counts[loop]; + + if (cnt == 0) { + zeros++; + min = 0; + continue; + } + + tot += cnt; + if (tot > max) + max = tot; + if (tot < min) + min = tot; + } + + if (verbose && tot > 0) { + printk("%s:", what); + + for (loop = 0; loop < num; loop++) { + cnt = counts[loop]; + + if (cnt == 0) + printk(" zzz"); + else + printk(" %d%%", cnt * 100 / tot); + } + + printk("\n"); + } + + return tot; +} + +/*****************************************************************************/ +/* + * + */ +static int __init do_tests(void) +{ + unsigned long loop; + unsigned int mutex_total, sem_total, rd_total, wr_total, dg_total; + + if (nummx < 0 || nummx > MAX_THREADS || + numsm < 0 || numsm > MAX_THREADS || + numrd < 0 || numrd > MAX_THREADS || + numwr < 0 || numwr > MAX_THREADS || + numdg < 0 || numdg > MAX_THREADS || + seminit < 1 || + elapse < 1 || + load < 0 || load > 999 || + interval < 0 || interval > 999 + ) { + printk("Parameter out of range\n"); + return -ERANGE; + } + + if ((nummx | numsm | numrd | numwr | numdg) == 0) { + int num = num_online_cpus(); + + if (num > MAX_THREADS) + num = MAX_THREADS; + nummx = numsm = numrd = numwr = numdg = num; + + load = 1; + interval = 1; + do_sched = 1; + printk("No parameters - using defaults.\n"); + } + + if (verbose) + printk("\nStarting synchronisation primitive tests...\n"); + + mutex_init(&mutex); + sema_init(&sem, seminit); + init_rwsem(&rwsem); + atomic_set(&do_stuff, 1); + + /* kick off all the children */ + for (loop = 0; loop < MAX_THREADS; loop++) { + if (loop < nummx) { + init_completion(&mx_comp[loop]); + kernel_thread(mutexer, (void *) loop, 0); + } + + if (loop < numsm) { + init_completion(&sm_comp[loop]); + kernel_thread(semaphorer, (void *) loop, 0); + } + + if (loop < numrd) { + init_completion(&rd_comp[loop]); + kernel_thread(reader, (void *) loop, 0); + } + + if (loop < numwr) { + init_completion(&wr_comp[loop]); + kernel_thread(writer, (void *) loop, 0); + } + + if (loop < numdg) { + init_completion(&dg_comp[loop]); + kernel_thread(downgrader, (void *) loop, 0); + } + } + + /* set a stop timer */ + init_timer(&timer); + timer.function = stop_test; + timer.expires = jiffies + elapse * HZ; + add_timer(&timer); + + /* now wait until it's all done */ + for (loop = 0; loop < nummx; loop++) + wait_for_completion(&mx_comp[loop]); + + for (loop = 0; loop < numsm; loop++) + wait_for_completion(&sm_comp[loop]); + + for (loop = 0; loop < numrd; loop++) + wait_for_completion(&rd_comp[loop]); + + for (loop = 0; loop < numwr; loop++) + wait_for_completion(&wr_comp[loop]); + + for (loop = 0; loop < numdg; loop++) + wait_for_completion(&dg_comp[loop]); + + atomic_set(&do_stuff, 0); + del_timer(&timer); + + if (mutex_is_locked(&mutex)) + printk(KERN_ERR "Mutex is still locked!\n"); + + /* count up */ + mutex_total = total("MTX", mutexes_taken, nummx); + sem_total = total("SEM", semaphores_taken, numsm); + rd_total = total("RD ", reads_taken, numrd); + wr_total = total("WR ", writes_taken, numwr); + dg_total = total("DG ", downgrades_taken, numdg); + + /* print the results */ + if (verbose) { + printk("mutexes taken: %u\n", mutex_total); + printk("semaphores taken: %u\n", sem_total); + printk("reads taken: %u\n", rd_total); + printk("writes taken: %u\n", wr_total); + printk("downgrades taken: %u\n", dg_total); + } + else { + char buf[30]; + + sprintf(buf, "%d/%d", interval, load); + + printk("%3d %3d %3d %3d %3d %c %5s %9u %9u %9u %9u %9u\n", + nummx, numsm, numrd, numwr, numdg, + do_sched ? 's' : '-', + buf, + mutex_total, + sem_total, + rd_total, + wr_total, + dg_total); + } + + /* tell insmod to discard the module */ + if (verbose) + printk("Tests complete\n"); + return -ENOANO; + +} /* end do_tests() */ + +module_init(do_tests); diff -puN lib/Kconfig.debug~mutex-subsystem-synchro-test-module lib/Kconfig.debug --- 25/lib/Kconfig.debug~mutex-subsystem-synchro-test-module Fri Jan 6 17:04:58 2006 +++ 25-akpm/lib/Kconfig.debug Fri Jan 6 17:04:58 2006 @@ -208,3 +208,17 @@ config RCU_TORTURE_TEST 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 DEBUG_SYNCHRO_TEST + tristate "Synchronisation primitive testing module" + depends on DEBUG_KERNEL + default n + help + This option provides a kernel module that can thrash the sleepable + synchronisation primitives (mutexes and semaphores). + + You should say N or M here. Whilst the module can be built in, it's + not recommended as it requires module parameters supplying to get it + to do anything. + + See Documentation/synchro-test.txt. _