Hi Mathieu,
On Tue, 2009-03-17 at 11:41 -0400, Mathieu Desnoyers wrote:
> * Subrata Modak ([email protected]) wrote:
> > Hi Mathieu,
> >
> > On Tue, Mar 17, 2009 at 7:02 AM, Mathieu Desnoyers <
> > [email protected]> wrote:
> >
> > > Hi,
> > >
> > > I am trying to get access to some non-x86 hardware to run some atomic
> > > primitive benchmarks for a paper on LTTng I am preparing. That should be
> > > useful to argue about performance benefit of per-cpu atomic operations
> > > vs interrupt disabling. I would like to run the following benchmark
> > > module on CONFIG_SMP :
> > >
> > > - PowerPC
> > > - MIPS
> > > - ia64
> > > - alpha
> > >
> > > usage :
> > > make
> > > insmod test-cmpxchg-nolock.ko
> > > insmod: error inserting 'test-cmpxchg-nolock.ko': -1 Resource temporarily
> > > unavailable
> > > dmesg (see dmesg output)
> > >
> >
> > With your permission, can we include this test in LTP (
> > http://ltp.sourceforge.net/), in some appropriate place as a small benchmark
> > test ?
> >
>
> Hi Subrata,
>
> Sure, maybe you'll want to use a better interface than a module init
> that fails though. :)
Please Cc me when you come up with a better interface. Meanwhile, i will
find out a better way to integrate this with LTP and will notify you
when i do that. Thanks.
Regards--
Subrata
>
> Mathieu
>
> > Regards--
> > Subrata
> >
> >
> > > If some of you would be kind enough to run my test module provided below
> > > and provide the results of these tests on a recent kernel (2.6.26~2.6.29
> > > should be good) along with their cpuinfo, I would greatly appreciate.
> > >
> > > Here are the CAS results for various Intel-based architectures :
> > >
> > > Architecture | Speedup | CAS |
> > > Interrupts |
> > > | (cli + sti) / local cmpxchg | local | sync | Enable
> > > (sti) | Disable (cli)
> > >
> > > -------------------------------------------------------------------------------------------------
> > > Intel Pentium 4 | 5.24 | 25 | 81 | 70
> > > | 61 |
> > > AMD Athlon(tm)64 X2 | 4.57 | 7 | 17 | 17
> > > | 15 |
> > > Intel Core2 | 6.33 | 6 | 30 | 20
> > > | 18 |
> > > Intel Xeon E5405 | 5.25 | 8 | 24 | 20
> > > | 22 |
> > >
> > > The benefit expected on PowerPC, ia64 and alpha should principally come
> > > from removed memory barriers in the local primitives.
> > >
> > > Thanks,
> > >
> > > Mathieu
> > >
> > > P.S. please forgive the coding style and hackish interface. :)
> > >
> > >
> > > /* test-cmpxchg-nolock.c
> > > *
> > > * Compare local cmpxchg with irq disable / enable.
> > > */
> > >
> > >
> > > #include <linux/jiffies.h>
> > > #include <linux/compiler.h>
> > > #include <linux/init.h>
> > > #include <linux/module.h>
> > > #include <linux/math64.h>
> > > #include <asm/timex.h>
> > > #include <asm/system.h>
> > >
> > > #define NR_LOOPS 20000
> > >
> > > int test_val;
> > >
> > > static void do_testbaseline(void)
> > > {
> > > unsigned long flags;
> > > unsigned int i;
> > > cycles_t time1, time2, time;
> > > u32 rem;
> > >
> > > local_irq_save(flags);
> > > preempt_disable();
> > > time1 = get_cycles();
> > > for (i = 0; i < NR_LOOPS; i++) {
> > > asm volatile ("");
> > > }
> > > time2 = get_cycles();
> > > local_irq_restore(flags);
> > > preempt_enable();
> > > time = time2 - time1;
> > >
> > > printk(KERN_ALERT "test results: time for baseline\n");
> > > printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
> > > printk(KERN_ALERT "total time: %llu\n", time);
> > > time = div_u64_rem(time, NR_LOOPS, &rem);
> > > printk(KERN_ALERT "-> baseline takes %llu cycles\n", time);
> > > printk(KERN_ALERT "test end\n");
> > > }
> > >
> > > static void do_test_sync_cmpxchg(void)
> > > {
> > > int ret;
> > > unsigned long flags;
> > > unsigned int i;
> > > cycles_t time1, time2, time;
> > > u32 rem;
> > >
> > > local_irq_save(flags);
> > > preempt_disable();
> > > time1 = get_cycles();
> > > for (i = 0; i < NR_LOOPS; i++) {
> > > #ifdef CONFIG_X86_32
> > > ret = sync_cmpxchg(&test_val, 0, 0);
> > > #else
> > > ret = cmpxchg(&test_val, 0, 0);
> > > #endif
> > > }
> > > time2 = get_cycles();
> > > local_irq_restore(flags);
> > > preempt_enable();
> > > time = time2 - time1;
> > >
> > > printk(KERN_ALERT "test results: time for locked cmpxchg\n");
> > > printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
> > > printk(KERN_ALERT "total time: %llu\n", time);
> > > time = div_u64_rem(time, NR_LOOPS, &rem);
> > > printk(KERN_ALERT "-> locked cmpxchg takes %llu cycles\n", time);
> > > printk(KERN_ALERT "test end\n");
> > > }
> > >
> > > static void do_test_cmpxchg(void)
> > > {
> > > int ret;
> > > unsigned long flags;
> > > unsigned int i;
> > > cycles_t time1, time2, time;
> > > u32 rem;
> > >
> > > local_irq_save(flags);
> > > preempt_disable();
> > > time1 = get_cycles();
> > > for (i = 0; i < NR_LOOPS; i++) {
> > > ret = cmpxchg_local(&test_val, 0, 0);
> > > }
> > > time2 = get_cycles();
> > > local_irq_restore(flags);
> > > preempt_enable();
> > > time = time2 - time1;
> > >
> > > printk(KERN_ALERT "test results: time for non locked cmpxchg\n");
> > > printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
> > > printk(KERN_ALERT "total time: %llu\n", time);
> > > time = div_u64_rem(time, NR_LOOPS, &rem);
> > > printk(KERN_ALERT "-> non locked cmpxchg takes %llu cycles\n",
> > > time);
> > > printk(KERN_ALERT "test end\n");
> > > }
> > > static void do_test_sync_inc(void)
> > > {
> > > int ret;
> > > unsigned long flags;
> > > unsigned int i;
> > > cycles_t time1, time2, time;
> > > u32 rem;
> > > atomic_t val;
> > >
> > > local_irq_save(flags);
> > > preempt_disable();
> > > time1 = get_cycles();
> > > for (i = 0; i < NR_LOOPS; i++) {
> > > ret = atomic_add_return(10, &val);
> > > }
> > > time2 = get_cycles();
> > > local_irq_restore(flags);
> > > preempt_enable();
> > > time = time2 - time1;
> > >
> > > printk(KERN_ALERT "test results: time for locked add return\n");
> > > printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
> > > printk(KERN_ALERT "total time: %llu\n", time);
> > > time = div_u64_rem(time, NR_LOOPS, &rem);
> > > printk(KERN_ALERT "-> locked add return takes %llu cycles\n",
> > > time);
> > > printk(KERN_ALERT "test end\n");
> > > }
> > >
> > >
> > > static void do_test_inc(void)
> > > {
> > > int ret;
> > > unsigned long flags;
> > > unsigned int i;
> > > cycles_t time1, time2, time;
> > > u32 rem;
> > > local_t loc_val;
> > >
> > > local_irq_save(flags);
> > > preempt_disable();
> > > time1 = get_cycles();
> > > for (i = 0; i < NR_LOOPS; i++) {
> > > ret = local_add_return(10, &loc_val);
> > > }
> > > time2 = get_cycles();
> > > local_irq_restore(flags);
> > > preempt_enable();
> > > time = time2 - time1;
> > >
> > > printk(KERN_ALERT "test results: time for non locked add
> > > return\n");
> > > printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
> > > printk(KERN_ALERT "total time: %llu\n", time);
> > > time = div_u64_rem(time, NR_LOOPS, &rem);
> > > printk(KERN_ALERT "-> non locked add return takes %llu cycles\n",
> > > time);
> > > printk(KERN_ALERT "test end\n");
> > > }
> > >
> > >
> > >
> > > /*
> > > * This test will have a higher standard deviation due to incoming
> > > interrupts.
> > > */
> > > static void do_test_enable_int(void)
> > > {
> > > unsigned long flags;
> > > unsigned int i;
> > > cycles_t time1, time2, time;
> > > u32 rem;
> > >
> > > local_irq_save(flags);
> > > preempt_disable();
> > > time1 = get_cycles();
> > > for (i = 0; i < NR_LOOPS; i++) {
> > > local_irq_restore(flags);
> > > }
> > > time2 = get_cycles();
> > > local_irq_restore(flags);
> > > preempt_enable();
> > > time = time2 - time1;
> > >
> > > printk(KERN_ALERT "test results: time for enabling interrupts
> > > (STI)\n");
> > > printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
> > > printk(KERN_ALERT "total time: %llu\n", time);
> > > time = div_u64_rem(time, NR_LOOPS, &rem);
> > > printk(KERN_ALERT "-> enabling interrupts (STI) takes %llu
> > > cycles\n",
> > > time);
> > > printk(KERN_ALERT "test end\n");
> > > }
> > >
> > > static void do_test_disable_int(void)
> > > {
> > > unsigned long flags, flags2;
> > > unsigned int i;
> > > cycles_t time1, time2, time;
> > > u32 rem;
> > >
> > > local_irq_save(flags);
> > > preempt_disable();
> > > time1 = get_cycles();
> > > for ( i = 0; i < NR_LOOPS; i++) {
> > > local_irq_save(flags2);
> > > }
> > > time2 = get_cycles();
> > > local_irq_restore(flags);
> > > preempt_enable();
> > > time = time2 - time1;
> > >
> > > printk(KERN_ALERT "test results: time for disabling interrupts
> > > (CLI)\n");
> > > printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
> > > printk(KERN_ALERT "total time: %llu\n", time);
> > > time = div_u64_rem(time, NR_LOOPS, &rem);
> > > printk(KERN_ALERT "-> disabling interrupts (CLI) takes %llu
> > > cycles\n",
> > > time);
> > > printk(KERN_ALERT "test end\n");
> > > }
> > >
> > > static void do_test_int(void)
> > > {
> > > unsigned long flags;
> > > unsigned int i;
> > > cycles_t time1, time2, time;
> > > u32 rem;
> > >
> > > local_irq_save(flags);
> > > preempt_disable();
> > > time1 = get_cycles();
> > > for (i = 0; i < NR_LOOPS; i++) {
> > > local_irq_restore(flags);
> > > local_irq_save(flags);
> > > }
> > > time2 = get_cycles();
> > > local_irq_restore(flags);
> > > preempt_enable();
> > > time = time2 - time1;
> > >
> > > printk(KERN_ALERT "test results: time for disabling/enabling
> > > interrupts (STI/CLI)\n");
> > > printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
> > > printk(KERN_ALERT "total time: %llu\n", time);
> > > time = div_u64_rem(time, NR_LOOPS, &rem);
> > > printk(KERN_ALERT "-> enabling/disabling interrupts (STI/CLI) takes
> > > %llu cycles\n",
> > > time);
> > > printk(KERN_ALERT "test end\n");
> > > }
> > >
> > >
> > >
> > > static int ltt_test_init(void)
> > > {
> > > printk(KERN_ALERT "test init\n");
> > >
> > > do_testbaseline();
> > > do_test_sync_cmpxchg();
> > > do_test_cmpxchg();
> > > do_test_sync_inc();
> > > do_test_inc();
> > > do_test_enable_int();
> > > do_test_disable_int();
> > > do_test_int();
> > > return -EAGAIN; /* Fail will directly unload the module */
> > > }
> > >
> > > static void ltt_test_exit(void)
> > > {
> > > printk(KERN_ALERT "test exit\n");
> > > }
> > >
> > > module_init(ltt_test_init)
> > > module_exit(ltt_test_exit)
> > >
> > > MODULE_LICENSE("GPL");
> > > MODULE_AUTHOR("Mathieu Desnoyers");
> > > MODULE_DESCRIPTION("Cmpxchg vs int Test");
> > >
> > >
> > >
> > > * Makefile
> > >
> > > ifneq ($(KERNELRELEASE),)
> > > obj-m += test-cmpxchg-nolock.o
> > > else
> > > KERNELDIR ?= /lib/modules/$(shell uname -r)/build
> > > PWD := $(shell pwd)
> > > KERNELRELEASE = $(shell cat
> > > $(KERNELDIR)/$(KBUILD_OUTPUT)/include/linux/version.h | sed -n
> > > 's/.*UTS_RELEASE.*\"\(.*\)\".*/\1/p')
> > > ifneq ($(INSTALL_MOD_PATH),)
> > > DEPMOD_OPT := -b $(INSTALL_MOD_PATH)
> > > endif
> > >
> > > default:
> > > $(MAKE) -C $(KERNELDIR) M=$(PWD) modules
> > >
> > > modules_install:
> > > $(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install
> > > if [ -f $(KERNELDIR)/$(KBUILD_OUTPUT)/System.map ] ; then
> > > /sbin/depmod -ae -F $(KERNELDIR)/$(KBUILD_OUTPUT)/System.map $(DEPMOD_OPT)
> > > $(KERNELRELEASE) ; fi
> > >
> > >
> > > clean:
> > > $(MAKE) -C $(KERNELDIR) M=$(PWD) clean
> > > endif
> > >
> > >
> > > --
> > > Mathieu Desnoyers
> > > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE
> > > 9A68
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > > the body of a message to [email protected]
> > > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > > Please read the FAQ at http://www.tux.org/lkml/
> > >
> >
> >
> >
> > --
> > Regards & Thanks--
> > Subrata
>
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