Messages in this thread | | | Subject | Re: Re: [PATCH v2] bit_spinlock: introduce smp_cond_load_relaxed | From | Gao Xiang <> | Date | Tue, 6 Nov 2018 01:11:44 +0800 |
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Hi all,
ping... is there someone interested in this patch?
It seems bit_spinlock performs much better by using smp_cond_load_relaxed than just do busy-loop in arm64...
Thanks, Gao Xiang
On 2018/10/30 13:52, Gao Xiang wrote: > Hi, > > On 2018/10/30 14:04, Gao Xiang wrote: >> It is better to use wrapped smp_cond_load_relaxed >> instead of open-coded busy waiting for bit_spinlock. >> >> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com> >> --- >> >> change log v2: >> - fix the incorrect expression !(VAL >> (bitnum & (BITS_PER_LONG-1))) >> - the test result is described in the following reply. >> >> Thanks, >> Gao Xiang > > > Simple test script: > #include <linux/kthread.h> > #include <linux/bit_spinlock.h> > #include <linux/module.h> > > unsigned long global_lock; > > int test_thread(void *data) > { > unsigned long thread_id = (unsigned long)data; > int i; > u64 start = ktime_get_ns(); > > for (i = 0; i < 500000; ++i) { > bit_spin_lock(0, &global_lock); > __asm__("yield"); > bit_spin_unlock(0, &global_lock); > } > pr_err("Thread id: %lu time: %llu\n", thread_id, ktime_get_ns() - start); > > do_exit(0); > } > > > static int __init bitspinlock_test_module_init(void) > { > int i; > > for (i = 0; i < 8; ++i) { > if (IS_ERR(kthread_run(test_thread, (void *)(unsigned long)i, "thread-%d", i))) > pr_err("fail to create thread %d\n", i); > } > > return 0; > } > > static void __exit bitspinlock_test_module_exit(void) > { > } > > module_init(bitspinlock_test_module_init); > module_exit(bitspinlock_test_module_exit); > MODULE_LICENSE("GPL"); > > > ...and tested in the following ARM server environment: > > Processor: HI1616 (https://en.wikichip.org/wiki/hisilicon/hi16xx/hi1616) > Board: HiSilicon D05 Development Board (http://open-estuary.org/d05/) > Memory: 512GB > Host OS: Ubuntu 18.04.1 LTS (Ubuntu 4.15.0-29.31-generic 4.15.18) > QEMU KVM OS: Linux 4.19 + buildroot > QEMU KVM cmdline: qemu-system-aarch64 -enable-kvm -cpu host -smp 4 -m 256M -kernel Image -M virt,kernel_irqchip=on -nographic -hda rootfs.ext2 -append 'root=/dev/vda console=ttyAMA0 earlycon=pl011,0x9000000' -serial mon:stdio -net none > > Without this patch: > Thread 0 Thread 1 Thread 2 Thread 3 Thread 4 Thread 5 Thread 6 Thread 7 > 1 1283709480 1271869280 454742480 1173673820 1145643640 1118846920 774616920 1144146140 > 2 643580180 625143860 576841700 322982340 649987880 585749000 529178880 373374780 > 3 672307220 847315000 880801860 1039502040 667086380 1033939940 1035381120 1046898300 > 4 568635580 440547020 737000380 910040880 804543740 712314280 868896880 867049000 > 5 749107320 726397720 776134480 611970100 756721040 753449440 711691300 609343300 > > With this patch: > Thread 0 Thread 1 Thread 2 Thread 3 Thread 4 Thread 5 Thread 6 Thread 7 > 1 170327620 196322160 169434180 74723860 178145600 178873460 143843260 70998780 > 2 166415220 129649200 166161240 175241520 155474460 112811860 157003140 150087420 > 3 511420780 117655640 598641860 596213720 462888760 430838600 554346300 428035120 > 4 174520240 156311800 120274280 87465380 172781400 136118620 163728340 63026360 > 5 153677940 202786860 183626500 140721300 150311360 161266840 168154340 107247460 > > Thanks, > Gao Xiang >
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