Re: [LKP] [bpf] fd978bf7fd: will-it-scale.per_process_ops -4.0% regression

Daniel Borkmann
2018-11-02T08:37:09Z

Hi Rong,

On 11/02/2018 03:14 AM, kernel test robot wrote:
> Greeting,
>
> FYI, we noticed a -4.0% regression of will-it-scale.per_process_ops due to commit:
>
>
> commit: fd978bf7fd312581a7ca454a991f0ffb34c4204b ("bpf: Add reference tracking to verifier")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
> in testcase: will-it-scale
> on test machine: 80 threads Skylake with 64G memory
> with following parameters:
>
> nr_task: 100%
> mode: process
> test: mmap1
> cpufreq_governor: performance

Hmm, so the test cases you are running are these ones:

https://github.com/antonblanchard/will-it-scale/blob/master/tests/mmap1.c
https://github.com/antonblanchard/will-it-scale/blob/master/tests/mmap2.c

The commit from Joe referenced above only adds a feature to the (eBPF) verifier. Looking
through will-it-scale test suite, looks like there's neither cBPF nor eBPF in use and if
it would have been the former (e.g. via seccomp BPF), then also this has no effect on it
since this doesn't load through bpf(2); meaning if so then something must use eBPF here,
but then it's also unclear right now how this would even remotely affect mmap() test
performance by -4%. Hm, are you certain it's not a false bisection? If so, what else is
loading eBPF on your machine in parallel when you run the tests?

Thanks,
Daniel

> test-description: Will It Scale takes a testcase and runs it from 1 through to n parallel copies to see if the testcase will scale. It builds both a process and threads based test in order to see any differences between the two.
> test-url: https://github.com/antonblanchard/will-it-scale
>
> In addition to that, the commit also has significant impact on the following tests:
>
> +------------------+---------------------------------------------------------------+
> | testcase: change | will-it-scale: will-it-scale.per_process_ops -3.8% regression |
> | test machine | 80 threads Skylake with 64G memory |
> | test parameters | cpufreq_governor=performance |
> | | mode=process |
> | | nr_task=100% |
> | | test=mmap2 |
> +------------------+---------------------------------------------------------------+
>
>
> Details are as below:
> -------------------------------------------------------------------------------------------------->
>
>
> To reproduce:
>
> git clone https://github.com/intel/lkp-tests.git
> cd lkp-tests
> bin/lkp install job.yaml # job file is attached in this email
> bin/lkp run job.yaml
>
> =========================================================================================
> compiler/cpufreq_governor/kconfig/mode/nr_task/rootfs/tbox_group/test/testcase:
> gcc-7/performance/x86_64-rhel-7.2/process/100%/debian-x86_64-2018-04-03.cgz/lkp-skl-2sp2/mmap1/will-it-scale
>
> commit:
> 84dbf35073 ("bpf: Macrofy stack state copy")
> fd978bf7fd ("bpf: Add reference tracking to verifier")
>
> 84dbf3507349696b fd978bf7fd312581a7ca454a99
> ---------------- --------------------------
> %stddev %change %stddev
> \ | \
> 16811 -4.0% 16140 will-it-scale.per_process_ops
> 1344946 -4.0% 1291230 will-it-scale.workload
> 107.75 ± 38% +252.4% 379.75 ± 93% cpuidle.POLL.usage
> 121.70 ± 18% +18.9% 144.70 ± 4% sched_debug.cfs_rq:/.exec_clock.stddev
> 4933 +2.0% 5031 proc-vmstat.nr_inactive_anon
> 4933 +2.0% 5031 proc-vmstat.nr_zone_inactive_anon
> 9874 +9.0% 10765 ± 7% slabinfo.proc_inode_cache.active_objs
> 9874 +9.0% 10765 ± 7% slabinfo.proc_inode_cache.num_objs
> 12248 ± 50% +52.2% 18640 ± 2% numa-meminfo.node0.Inactive
> 33943 ± 8% +16.2% 39453 ± 6% numa-meminfo.node0.SReclaimable
> 91549 ± 9% -9.9% 82530 ± 7% numa-meminfo.node1.Slab
> 18091 ± 15% +29.2% 23382 ± 17% numa-vmstat.node0
> 3027 ± 52% +52.6% 4620 ± 3% numa-vmstat.node0.nr_inactive_anon
> 8485 ± 8% +16.2% 9862 ± 6% numa-vmstat.node0.nr_slab_reclaimable
> 3027 ± 52% +52.6% 4620 ± 3% numa-vmstat.node0.nr_zone_inactive_anon
> 1.4e+12 -2.5% 1.364e+12 perf-stat.branch-instructions
> 41.42 +0.7 42.15 perf-stat.cache-miss-rate%
> 2.166e+10 -2.1% 2.12e+10 perf-stat.cache-references
> 12.16 +2.7% 12.49 perf-stat.cpi
> 1.741e+12 -2.8% 1.692e+12 perf-stat.dTLB-loads
> 0.00 ± 3% +0.0 0.00 ± 9% perf-stat.dTLB-store-miss-rate%
> 5.713e+11 -3.9% 5.49e+11 perf-stat.dTLB-stores
> 6.103e+12 -2.6% 5.943e+12 perf-stat.instructions
> 0.08 -2.6% 0.08 perf-stat.ipc
> 1.954e+09 -1.8% 1.919e+09 perf-stat.node-load-misses
> 4538060 +1.4% 4602862 perf-stat.path-length
> 49.62 -0.5 49.14 perf-profile.calltrace.cycles-pp.do_munmap.vm_munmap.__x64_sys_munmap.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 47.64 -0.5 47.17 perf-profile.calltrace.cycles-pp._raw_spin_lock_irqsave.percpu_counter_add_batch.do_munmap.vm_munmap.__x64_sys_munmap
> 47.49 -0.5 47.02 perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock_irqsave.percpu_counter_add_batch.do_munmap.vm_munmap
> 49.99 -0.5 49.53 perf-profile.calltrace.cycles-pp.__x64_sys_munmap.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 49.96 -0.5 49.51 perf-profile.calltrace.cycles-pp.vm_munmap.__x64_sys_munmap.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 48.02 -0.4 47.58 perf-profile.calltrace.cycles-pp.percpu_counter_add_batch.do_munmap.vm_munmap.__x64_sys_munmap.do_syscall_64
> 1.41 -0.0 1.37 perf-profile.calltrace.cycles-pp.unmap_region.do_munmap.vm_munmap.__x64_sys_munmap.do_syscall_64
> 47.73 +0.4 48.11 perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock_irqsave.percpu_counter_add_batch.__vm_enough_memory.mmap_region
> 47.85 +0.4 48.25 perf-profile.calltrace.cycles-pp._raw_spin_lock_irqsave.percpu_counter_add_batch.__vm_enough_memory.mmap_region.do_mmap
> 48.28 +0.4 48.68 perf-profile.calltrace.cycles-pp.__vm_enough_memory.mmap_region.do_mmap.vm_mmap_pgoff.ksys_mmap_pgoff
> 48.23 +0.4 48.63 perf-profile.calltrace.cycles-pp.percpu_counter_add_batch.__vm_enough_memory.mmap_region.do_mmap.vm_mmap_pgoff
> 48.96 +0.4 49.41 perf-profile.calltrace.cycles-pp.mmap_region.do_mmap.vm_mmap_pgoff.ksys_mmap_pgoff.do_syscall_64
> 49.11 +0.5 49.56 perf-profile.calltrace.cycles-pp.do_mmap.vm_mmap_pgoff.ksys_mmap_pgoff.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 49.24 +0.5 49.70 perf-profile.calltrace.cycles-pp.vm_mmap_pgoff.ksys_mmap_pgoff.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 49.25 +0.5 49.72 perf-profile.calltrace.cycles-pp.ksys_mmap_pgoff.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 49.62 -0.5 49.15 perf-profile.children.cycles-pp.do_munmap
> 49.99 -0.5 49.53 perf-profile.children.cycles-pp.__x64_sys_munmap
> 49.97 -0.5 49.51 perf-profile.children.cycles-pp.vm_munmap
> 0.51 ± 2% -0.0 0.46 perf-profile.children.cycles-pp.___might_sleep
> 1.16 -0.0 1.11 perf-profile.children.cycles-pp.unmap_vmas
> 1.15 -0.0 1.10 perf-profile.children.cycles-pp.unmap_page_range
> 1.41 -0.0 1.37 perf-profile.children.cycles-pp.unmap_region
> 0.32 ± 2% +0.0 0.34 ± 2% perf-profile.children.cycles-pp.up_write
> 0.32 ± 2% +0.0 0.34 perf-profile.children.cycles-pp.vm_area_alloc
> 0.29 +0.0 0.32 perf-profile.children.cycles-pp.kmem_cache_alloc
> 48.28 +0.4 48.68 perf-profile.children.cycles-pp.__vm_enough_memory
> 48.96 +0.4 49.41 perf-profile.children.cycles-pp.mmap_region
> 49.11 +0.5 49.56 perf-profile.children.cycles-pp.do_mmap
> 49.25 +0.5 49.71 perf-profile.children.cycles-pp.vm_mmap_pgoff
> 49.25 +0.5 49.72 perf-profile.children.cycles-pp.ksys_mmap_pgoff
> 0.47 ± 3% -0.0 0.43 perf-profile.self.cycles-pp.___might_sleep
> 0.32 ± 3% +0.0 0.34 ± 2% perf-profile.self.cycles-pp.up_write
> 0.27 +0.0 0.30 perf-profile.self.cycles-pp.kmem_cache_alloc
> 0.49 +0.0 0.53 perf-profile.self.cycles-pp.percpu_counter_add_batch
>
>
>
> will-it-scale.per_process_ops
>
> 18000 +-+-----------------------------------------------------------------+
> | |
> 17500 +-+ +.+ |
> |+.+++ : +.++++.+++ ++++.++++.++ |
> | :++. + : : : : |
> 17000 +-+ + + ++.++: : ++.+++ : ++.+ ++. +. |
> | + +.+ + + +++ +|
> 16500 +-+ |
> | O OOOO OOOO O O |
> 16000 +-+ O O O O O |
> | |
> O O OOO O |
> 15500 +O+OOO O |
> | |
> 15000 +-+-----------------------------------------------------------------+
>
>
> will-it-scale.workload
>
> 1.42e+06 +-+--------------------------------------------------------------+
> 1.4e+06 +-+ ++ |
> |++.++ : ++. +++.+ |
> 1.38e+06 +-+ : +.+++ ++ ++++.++ : |
> 1.36e+06 +-+ +.+++++. : : : :+ |
> | ++++ ++.+++++.+ + ++.+++++.++|
> 1.34e+06 +-+ |
> 1.32e+06 +-+ |
> 1.3e+06 +-+ O |
> | OO OO OO OOOOO OOO |
> 1.28e+06 +-+ O |
> 1.26e+06 +-+ O |
> O O O OO |
> 1.24e+06 +OO OO O |
> 1.22e+06 +-+--------------------------------------------------------------+
>
>
> [*] bisect-good sample
> [O] bisect-bad sample
>
> ***************************************************************************************************
> lkp-skl-2sp2: 80 threads Skylake with 64G memory
> =========================================================================================
> compiler/cpufreq_governor/kconfig/mode/nr_task/rootfs/tbox_group/test/testcase:
> gcc-7/performance/x86_64-rhel-7.2/process/100%/debian-x86_64-2018-04-03.cgz/lkp-skl-2sp2/mmap2/will-it-scale
>
> commit:
> 84dbf35073 ("bpf: Macrofy stack state copy")
> fd978bf7fd ("bpf: Add reference tracking to verifier")
>
> 84dbf3507349696b fd978bf7fd312581a7ca454a99
> ---------------- --------------------------
> %stddev %change %stddev
> \ | \
> 16832 -3.8% 16186 will-it-scale.per_process_ops
> 1346634 -3.8% 1294984 will-it-scale.workload
> 390809 ± 21% +51.6% 592424 ± 27% cpuidle.C1.time
> 6897 +2.7% 7085 proc-vmstat.nr_mapped
> 936.00 ± 7% +15.6% 1082 ± 5% slabinfo.Acpi-ParseExt.active_objs
> 936.00 ± 7% +15.6% 1082 ± 5% slabinfo.Acpi-ParseExt.num_objs
> 968.00 ± 9% +27.5% 1233 ± 16% slabinfo.pool_workqueue.active_objs
> 968.00 ± 9% +29.7% 1255 ± 16% slabinfo.pool_workqueue.num_objs
> 8430 -14.1% 7244 ± 2% numa-meminfo.node0.KernelStack
> 4283 ± 14% -22.4% 3325 ± 10% numa-meminfo.node0.PageTables
> 73929 ± 3% -10.6% 66061 ± 6% numa-meminfo.node0.SUnreclaim
> 5569 ± 2% +21.0% 6738 ± 3% numa-meminfo.node1.KernelStack
> 55085 ± 5% +17.5% 64739 ± 5% numa-meminfo.node1.SUnreclaim
> 81155 ± 6% +16.2% 94292 ± 7% numa-meminfo.node1.Slab
> 230.00 -100.0% 0.00 numa-vmstat.node0.nr_active_file
> 100.25 ± 3% -88.8% 11.25 ±173% numa-vmstat.node0.nr_inactive_file
> 8431 -14.1% 7245 ± 2% numa-vmstat.node0.nr_kernel_stack
> 1071 ± 14% -22.4% 831.25 ± 10% numa-vmstat.node0.nr_page_table_pages
> 18482 ± 3% -10.6% 16515 ± 6% numa-vmstat.node0.nr_slab_unreclaimable
> 230.00 -100.0% 0.00 numa-vmstat.node0.nr_zone_active_file
> 100.25 ± 3% -88.8% 11.25 ±173% numa-vmstat.node0.nr_zone_inactive_file
> 5569 ± 2% +21.0% 6738 ± 3% numa-vmstat.node1.nr_kernel_stack
> 2778 ± 3% +28.4% 3567 ± 16% numa-vmstat.node1.nr_mapped
> 13771 ± 5% +17.5% 16184 ± 5% numa-vmstat.node1.nr_slab_unreclaimable
> 1.506e+12 -2.5% 1.468e+12 perf-stat.branch-instructions
> 41.41 +0.8 42.20 perf-stat.cache-miss-rate%
> 2.165e+10 -1.7% 2.129e+10 perf-stat.cache-references
> 11.25 +2.8% 11.57 perf-stat.cpi
> 1.891e+12 -2.8% 1.838e+12 perf-stat.dTLB-loads
> 6.543e+11 -3.7% 6.3e+11 perf-stat.dTLB-stores
> 6.591e+12 -2.6% 6.419e+12 perf-stat.instructions
> 0.09 -2.7% 0.09 perf-stat.ipc
> 1.967e+09 -1.3% 1.941e+09 perf-stat.node-load-misses
> 4894750 +1.3% 4956596 perf-stat.path-length
> 40.37 ± 12% -16.2% 33.81 ± 7% sched_debug.cfs_rq:/.load_avg.stddev
> 0.05 ± 2% +18.7% 0.06 ± 3% sched_debug.cfs_rq:/.nr_running.stddev
> 6.37 ± 40% -50.2% 3.17 ± 32% sched_debug.cfs_rq:/.removed.load_avg.avg
> 31.64 ± 18% -28.5% 22.63 ± 16% sched_debug.cfs_rq:/.removed.load_avg.stddev
> 293.89 ± 40% -50.1% 146.61 ± 32% sched_debug.cfs_rq:/.removed.runnable_sum.avg
> 1459 ± 18% -28.3% 1045 ± 16% sched_debug.cfs_rq:/.removed.runnable_sum.stddev
> 2.46 ± 43% -60.9% 0.96 ± 66% sched_debug.cfs_rq:/.removed.util_avg.avg
> 12.42 ± 26% -46.5% 6.64 ± 59% sched_debug.cfs_rq:/.removed.util_avg.stddev
> 385.92 ± 6% +12.8% 435.46 ± 2% sched_debug.cpu.nr_switches.min
> -14.21 -31.4% -9.75 sched_debug.cpu.nr_uninterruptible.min
> 47.54 -0.2 47.31 perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock_irqsave.percpu_counter_add_batch.do_munmap.vm_munmap
> 47.67 -0.2 47.45 perf-profile.calltrace.cycles-pp._raw_spin_lock_irqsave.percpu_counter_add_batch.do_munmap.vm_munmap.__x64_sys_munmap
> 48.04 -0.2 47.86 perf-profile.calltrace.cycles-pp.percpu_counter_add_batch.do_munmap.vm_munmap.__x64_sys_munmap.do_syscall_64
> 99.36 -0.0 99.34 perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe
> 1.47 +0.0 1.51 perf-profile.calltrace.cycles-pp.unmap_region.do_munmap.vm_munmap.__x64_sys_munmap.do_syscall_64
> 94.77 -0.3 94.52 perf-profile.children.cycles-pp.native_queued_spin_lock_slowpath
> 95.04 -0.2 94.81 perf-profile.children.cycles-pp._raw_spin_lock_irqsave
> 95.77 -0.2 95.60 perf-profile.children.cycles-pp.percpu_counter_add_batch
> 49.72 -0.1 49.58 perf-profile.children.cycles-pp.do_munmap
> 0.53 ± 2% -0.1 0.47 perf-profile.children.cycles-pp.___might_sleep
> 0.30 ± 2% +0.0 0.33 perf-profile.children.cycles-pp.perf_event_mmap
> 0.30 ± 3% +0.0 0.33 ± 2% perf-profile.children.cycles-pp.vm_area_alloc
> 0.33 ± 2% +0.0 0.36 ± 2% perf-profile.children.cycles-pp.up_write
> 1.48 +0.0 1.51 perf-profile.children.cycles-pp.unmap_region
> 94.77 -0.3 94.52 perf-profile.self.cycles-pp.native_queued_spin_lock_slowpath
> 0.48 ± 2% -0.0 0.44 perf-profile.self.cycles-pp.___might_sleep
> 0.33 ± 2% +0.0 0.36 ± 2% perf-profile.self.cycles-pp.up_write
> 0.53 +0.0 0.57 perf-profile.self.cycles-pp.unmap_page_range
> 0.47 +0.0 0.52 ± 2% perf-profile.self.cycles-pp.percpu_counter_add_batch
>
>
>
>
>
> Disclaimer:
> Results have been estimated based on internal Intel analysis and are provided
> for informational purposes only. Any difference in system hardware or software
> design or configuration may affect actual performance.
>
>
> Thanks,
> Rong Chen
>