On 28/05/2018 10:22, Haiyan Song wrote: > Hi Laurent, > > Yes, these tests are done on V9 patch. Do you plan to give this V11 a run ? > > > Best regards, > Haiyan Song > > On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote: >> On 28/05/2018 07:23, Song, HaiyanX wrote: >>> >>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series >>> tested on Intel 4s Skylake platform. >> >> Hi, >> >> Thanks for reporting this benchmark results, but you mentioned the "V9 patch >> series" while responding to the v11 header series... >> Were these tests done on v9 or v11 ? >> >> Cheers, >> Laurent. >> >>> >>> The regression result is sorted by the metric will-it-scale.per_thread_ops. >>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series) >>> Commit id: >>> base commit: d55f34411b1b126429a823d06c3124c16283231f >>> head commit: 0355322b3577eeab7669066df42c550a56801110 >>> Benchmark suite: will-it-scale >>> Download link: >>> https://github.com/antonblanchard/will-it-scale/tree/master/tests >>> Metrics: >>> will-it-scale.per_process_ops=processes/nr_cpu >>> will-it-scale.per_thread_ops=threads/nr_cpu >>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G) >>> THP: enable / disable >>> nr_task: 100% >>> >>> 1. Regressions: >>> a) THP enabled: >>> testcase base change head metric >>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops >>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops >>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops >>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops >>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops >>> >>> b) THP disabled: >>> testcase base change head metric >>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops >>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops >>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops >>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops >>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops >>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops >>> >>> 2. Improvements: >>> a) THP enabled: >>> testcase base change head metric >>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops >>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops >>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops >>> >>> b) THP disabled: >>> testcase base change head metric >>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops >>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops >>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops >>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops >>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops >>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops >>> >>> Notes: for above values in column "change", the higher value means that the related testcase result >>> on head commit is better than that on base commit for this benchmark. >>> >>> >>> Best regards >>> Haiyan Song >>> >>> ________________________________________ >>> From: owner-linux-mm@xxxxxxxxx [owner-linux-mm@xxxxxxxxx] on behalf of Laurent Dufour [ldufour@xxxxxxxxxxxxxxxxxx] >>> Sent: Thursday, May 17, 2018 7:06 PM >>> To: akpm@xxxxxxxxxxxxxxxxxxxx; mhocko@xxxxxxxxxx; peterz@xxxxxxxxxxxxx; kirill@xxxxxxxxxxxxx; ak@xxxxxxxxxxxxxxx; dave@xxxxxxxxxxxx; jack@xxxxxxx; Matthew Wilcox; khandual@xxxxxxxxxxxxxxxxxx; aneesh.kumar@xxxxxxxxxxxxxxxxxx; benh@xxxxxxxxxxxxxxxxxxx; mpe@xxxxxxxxxxxxxx; paulus@xxxxxxxxx; Thomas Gleixner; Ingo Molnar; hpa@xxxxxxxxx; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@xxxxxxxxx; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi >>> Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; haren@xxxxxxxxxxxxxxxxxx; npiggin@xxxxxxxxx; bsingharora@xxxxxxxxx; paulmck@xxxxxxxxxxxxxxxxxx; Tim Chen; linuxppc-dev@xxxxxxxxxxxxxxxx; x86@xxxxxxxxxx >>> Subject: [PATCH v11 00/26] Speculative page faults >>> >>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle >>> page fault without holding the mm semaphore [1]. >>> >>> The idea is to try to handle user space page faults without holding the >>> mmap_sem. This should allow better concurrency for massively threaded >>> process since the page fault handler will not wait for other threads memory >>> layout change to be done, assuming that this change is done in another part >>> of the process's memory space. This type page fault is named speculative >>> page fault. If the speculative page fault fails because of a concurrency is >>> detected or because underlying PMD or PTE tables are not yet allocating, it >>> is failing its processing and a classic page fault is then tried. >>> >>> The speculative page fault (SPF) has to look for the VMA matching the fault >>> address without holding the mmap_sem, this is done by introducing a rwlock >>> which protects the access to the mm_rb tree. Previously this was done using >>> SRCU but it was introducing a lot of scheduling to process the VMA's >>> freeing operation which was hitting the performance by 20% as reported by >>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is >>> limiting the locking contention to these operations which are expected to >>> be in a O(log n) order. In addition to ensure that the VMA is not freed in >>> our back a reference count is added and 2 services (get_vma() and >>> put_vma()) are introduced to handle the reference count. Once a VMA is >>> fetched from the RB tree using get_vma(), it must be later freed using >>> put_vma(). I can't see anymore the overhead I got while will-it-scale >>> benchmark anymore. >>> >>> The VMA's attributes checked during the speculative page fault processing >>> have to be protected against parallel changes. This is done by using a per >>> VMA sequence lock. This sequence lock allows the speculative page fault >>> handler to fast check for parallel changes in progress and to abort the >>> speculative page fault in that case. >>> >>> Once the VMA has been found, the speculative page fault handler would check >>> for the VMA's attributes to verify that the page fault has to be handled >>> correctly or not. Thus, the VMA is protected through a sequence lock which >>> allows fast detection of concurrent VMA changes. If such a change is >>> detected, the speculative page fault is aborted and a *classic* page fault >>> is tried. VMA sequence lockings are added when VMA attributes which are >>> checked during the page fault are modified. >>> >>> When the PTE is fetched, the VMA is checked to see if it has been changed, >>> so once the page table is locked, the VMA is valid, so any other changes >>> leading to touching this PTE will need to lock the page table, so no >>> parallel change is possible at this time. >>> >>> The locking of the PTE is done with interrupts disabled, this allows >>> checking for the PMD to ensure that there is not an ongoing collapsing >>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is >>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is >>> valid at the time the PTE is locked, we have the guarantee that the >>> collapsing operation will have to wait on the PTE lock to move forward. >>> This allows the SPF handler to map the PTE safely. If the PMD value is >>> different from the one recorded at the beginning of the SPF operation, the >>> classic page fault handler will be called to handle the operation while >>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled, >>> the lock is done using spin_trylock() to avoid dead lock when handling a >>> page fault while a TLB invalidate is requested by another CPU holding the >>> PTE. >>> >>> In pseudo code, this could be seen as: >>> speculative_page_fault() >>> { >>> vma = get_vma() >>> check vma sequence count >>> check vma's support >>> disable interrupt >>> check pgd,p4d,...,pte >>> save pmd and pte in vmf >>> save vma sequence counter in vmf >>> enable interrupt >>> check vma sequence count >>> handle_pte_fault(vma) >>> .. >>> page = alloc_page() >>> pte_map_lock() >>> disable interrupt >>> abort if sequence counter has changed >>> abort if pmd or pte has changed >>> pte map and lock >>> enable interrupt >>> if abort >>> free page >>> abort >>> ... >>> } >>> >>> arch_fault_handler() >>> { >>> if (speculative_page_fault(&vma)) >>> goto done >>> again: >>> lock(mmap_sem) >>> vma = find_vma(); >>> handle_pte_fault(vma); >>> if retry >>> unlock(mmap_sem) >>> goto again; >>> done: >>> handle fault error >>> } >>> >>> Support for THP is not done because when checking for the PMD, we can be >>> confused by an in progress collapsing operation done by khugepaged. The >>> issue is that pmd_none() could be true either if the PMD is not already >>> populated or if the underlying PTE are in the way to be collapsed. So we >>> cannot safely allocate a PMD if pmd_none() is true. >>> >>> This series add a new software performance event named 'speculative-faults' >>> or 'spf'. It counts the number of successful page fault event handled >>> speculatively. When recording 'faults,spf' events, the faults one is >>> counting the total number of page fault events while 'spf' is only counting >>> the part of the faults processed speculatively. >>> >>> There are some trace events introduced by this series. They allow >>> identifying why the page faults were not processed speculatively. This >>> doesn't take in account the faults generated by a monothreaded process >>> which directly processed while holding the mmap_sem. This trace events are >>> grouped in a system named 'pagefault', they are: >>> - pagefault:spf_vma_changed : if the VMA has been changed in our back >>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set. >>> - pagefault:spf_vma_notsup : the VMA's type is not supported >>> - pagefault:spf_vma_access : the VMA's access right are not respected >>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our >>> back. >>> >>> To record all the related events, the easier is to run perf with the >>> following arguments : >>> $ perf stat -e 'faults,spf,pagefault:*' <command> >>> >>> There is also a dedicated vmstat counter showing the number of successful >>> page fault handled speculatively. I can be seen this way: >>> $ grep speculative_pgfault /proc/vmstat >>> >>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional >>> on x86, PowerPC and arm64. >>> >>> --------------------- >>> Real Workload results >>> >>> As mentioned in previous email, we did non official runs using a "popular >>> in memory multithreaded database product" on 176 cores SMT8 Power system >>> which showed a 30% improvements in the number of transaction processed per >>> second. This run has been done on the v6 series, but changes introduced in >>> this new version should not impact the performance boost seen. >>> >>> Here are the perf data captured during 2 of these runs on top of the v8 >>> series: >>> vanilla spf >>> faults 89.418 101.364 +13% >>> spf n/a 97.989 >>> >>> With the SPF kernel, most of the page fault were processed in a speculative >>> way. >>> >>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave >>> it a try on an android device. He reported that the application launch time >>> was improved in average by 6%, and for large applications (~100 threads) by >>> 20%. >>> >>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom >>> MSM845 (8 cores) with 6GB (the less is better): >>> >>> Application 4.9 4.9+spf delta >>> com.tencent.mm 416 389 -7% >>> com.eg.android.AlipayGphone 1135 986 -13% >>> com.tencent.mtt 455 454 0% >>> com.qqgame.hlddz 1497 1409 -6% >>> com.autonavi.minimap 711 701 -1% >>> com.tencent.tmgp.sgame 788 748 -5% >>> com.immomo.momo 501 487 -3% >>> com.tencent.peng 2145 2112 -2% >>> com.smile.gifmaker 491 461 -6% >>> com.baidu.BaiduMap 479 366 -23% >>> com.taobao.taobao 1341 1198 -11% >>> com.baidu.searchbox 333 314 -6% >>> com.tencent.mobileqq 394 384 -3% >>> com.sina.weibo 907 906 0% >>> com.youku.phone 816 731 -11% >>> com.happyelements.AndroidAnimal.qq 763 717 -6% >>> com.UCMobile 415 411 -1% >>> com.tencent.tmgp.ak 1464 1431 -2% >>> com.tencent.qqmusic 336 329 -2% >>> com.sankuai.meituan 1661 1302 -22% >>> com.netease.cloudmusic 1193 1200 1% >>> air.tv.douyu.android 4257 4152 -2% >>> >>> ------------------ >>> Benchmarks results >>> >>> Base kernel is v4.17.0-rc4-mm1 >>> SPF is BASE + this series >>> >>> Kernbench: >>> ---------- >>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15 >>> kernel (kernel is build 5 times): >>> >>> Average Half load -j 8 >>> Run (std deviation) >>> BASE SPF >>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50% >>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13% >>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53% >>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16% >>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74% >>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01% >>> >>> Average Optimal load -j 16 >>> Run (std deviation) >>> BASE SPF >>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75% >>> User Time 11064.8 (981.142) 11085 (990.897) 0.18% >>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17% >>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31% >>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79% >>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16% >>> >>> >>> During a run on the SPF, perf events were captured: >>> Performance counter stats for '../kernbench -M': >>> 526743764 faults >>> 210 spf >>> 3 pagefault:spf_vma_changed >>> 0 pagefault:spf_vma_noanon >>> 2278 pagefault:spf_vma_notsup >>> 0 pagefault:spf_vma_access >>> 0 pagefault:spf_pmd_changed >>> >>> Very few speculative page faults were recorded as most of the processes >>> involved are monothreaded (sounds that on this architecture some threads >>> were created during the kernel build processing). >>> >>> Here are the kerbench results on a 80 CPUs Power8 system: >>> >>> Average Half load -j 40 >>> Run (std deviation) >>> BASE SPF >>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01% >>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03% >>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24% >>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08% >>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50% >>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17% >>> >>> Average Optimal load -j 80 >>> Run (std deviation) >>> BASE SPF >>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39% >>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03% >>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23% >>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33% >>> Context Switches 223861 (138865) 225032 (139632) 0.52% >>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45% >>> >>> During a run on the SPF, perf events were captured: >>> Performance counter stats for '../kernbench -M': >>> 116730856 faults >>> 0 spf >>> 3 pagefault:spf_vma_changed >>> 0 pagefault:spf_vma_noanon >>> 476 pagefault:spf_vma_notsup >>> 0 pagefault:spf_vma_access >>> 0 pagefault:spf_pmd_changed >>> >>> Most of the processes involved are monothreaded so SPF is not activated but >>> there is no impact on the performance. >>> >>> Ebizzy: >>> ------- >>> The test is counting the number of records per second it can manage, the >>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get >>> consistent result I repeated the test 100 times and measure the average >>> result. The number is the record processes per second, the higher is the >>> best. >>> >>> BASE SPF delta >>> 16 CPUs x86 VM 742.57 1490.24 100.69% >>> 80 CPUs P8 node 13105.4 24174.23 84.46% >>> >>> Here are the performance counter read during a run on a 16 CPUs x86 VM: >>> Performance counter stats for './ebizzy -mTt 16': >>> 1706379 faults >>> 1674599 spf >>> 30588 pagefault:spf_vma_changed >>> 0 pagefault:spf_vma_noanon >>> 363 pagefault:spf_vma_notsup >>> 0 pagefault:spf_vma_access >>> 0 pagefault:spf_pmd_changed >>> >>> And the ones captured during a run on a 80 CPUs Power node: >>> Performance counter stats for './ebizzy -mTt 80': >>> 1874773 faults >>> 1461153 spf >>> 413293 pagefault:spf_vma_changed >>> 0 pagefault:spf_vma_noanon >>> 200 pagefault:spf_vma_notsup >>> 0 pagefault:spf_vma_access >>> 0 pagefault:spf_pmd_changed >>> >>> In ebizzy's case most of the page fault were handled in a speculative way, >>> leading the ebizzy performance boost. >>> >>> ------------------ >>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572): >>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran >>> and Minchan Kim, hopefully. >>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in >>> __do_page_fault(). >>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails >>> instead >>> of aborting the speculative page fault handling. Dropping the now >>> useless >>> trace event pagefault:spf_pte_lock. >>> - No more try to reuse the fetched VMA during the speculative page fault >>> handling when retrying is needed. This adds a lot of complexity and >>> additional tests done didn't show a significant performance improvement. >>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error. >>> >>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none >>> [2] https://patchwork.kernel.org/patch/9999687/ >>> >>> >>> Laurent Dufour (20): >>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT >>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT >>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT >>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE >>> mm: make pte_unmap_same compatible with SPF >>> mm: introduce INIT_VMA() >>> mm: protect VMA modifications using VMA sequence count >>> mm: protect mremap() against SPF hanlder >>> mm: protect SPF handler against anon_vma changes >>> mm: cache some VMA fields in the vm_fault structure >>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page() >>> mm: introduce __lru_cache_add_active_or_unevictable >>> mm: introduce __vm_normal_page() >>> mm: introduce __page_add_new_anon_rmap() >>> mm: protect mm_rb tree with a rwlock >>> mm: adding speculative page fault failure trace events >>> perf: add a speculative page fault sw event >>> perf tools: add support for the SPF perf event >>> mm: add speculative page fault vmstats >>> powerpc/mm: add speculative page fault >>> >>> Mahendran Ganesh (2): >>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT >>> arm64/mm: add speculative page fault >>> >>> Peter Zijlstra (4): >>> mm: prepare for FAULT_FLAG_SPECULATIVE >>> mm: VMA sequence count >>> mm: provide speculative fault infrastructure >>> x86/mm: add speculative pagefault handling >>> >>> arch/arm64/Kconfig | 1 + >>> arch/arm64/mm/fault.c | 12 + >>> arch/powerpc/Kconfig | 1 + >>> arch/powerpc/mm/fault.c | 16 + >>> arch/x86/Kconfig | 1 + >>> arch/x86/mm/fault.c | 27 +- >>> fs/exec.c | 2 +- >>> fs/proc/task_mmu.c | 5 +- >>> fs/userfaultfd.c | 17 +- >>> include/linux/hugetlb_inline.h | 2 +- >>> include/linux/migrate.h | 4 +- >>> include/linux/mm.h | 136 +++++++- >>> include/linux/mm_types.h | 7 + >>> include/linux/pagemap.h | 4 +- >>> include/linux/rmap.h | 12 +- >>> include/linux/swap.h | 10 +- >>> include/linux/vm_event_item.h | 3 + >>> include/trace/events/pagefault.h | 80 +++++ >>> include/uapi/linux/perf_event.h | 1 + >>> kernel/fork.c | 5 +- >>> mm/Kconfig | 22 ++ >>> mm/huge_memory.c | 6 +- >>> mm/hugetlb.c | 2 + >>> mm/init-mm.c | 3 + >>> mm/internal.h | 20 ++ >>> mm/khugepaged.c | 5 + >>> mm/madvise.c | 6 +- >>> mm/memory.c | 612 +++++++++++++++++++++++++++++----- >>> mm/mempolicy.c | 51 ++- >>> mm/migrate.c | 6 +- >>> mm/mlock.c | 13 +- >>> mm/mmap.c | 229 ++++++++++--- >>> mm/mprotect.c | 4 +- >>> mm/mremap.c | 13 + >>> mm/nommu.c | 2 +- >>> mm/rmap.c | 5 +- >>> mm/swap.c | 6 +- >>> mm/swap_state.c | 8 +- >>> mm/vmstat.c | 5 +- >>> tools/include/uapi/linux/perf_event.h | 1 + >>> tools/perf/util/evsel.c | 1 + >>> tools/perf/util/parse-events.c | 4 + >>> tools/perf/util/parse-events.l | 1 + >>> tools/perf/util/python.c | 1 + >>> 44 files changed, 1161 insertions(+), 211 deletions(-) >>> create mode 100644 include/trace/events/pagefault.h >>> >>> -- >>> 2.7.4 >>> >>> >> >
