On 04/07/2018 05:23, Song, HaiyanX wrote: > Hi Laurent, > > > For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times. > I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev. Repeating the test only 3 times seems a bit too low to me. I'll focus on the higher change for the moment, but I don't have access to such a hardware. Is possible to provide a diff between base and SPF of the performance cycles measured when running page_fault3 and page_fault2 when the 20% change is detected. Please stay focus on the test case process to see exactly where the series is impacting. Thanks, Laurent. > > And I did not find other high variation on test case result. > > a). Enable THP > testcase base stddev change head stddev metric > page_fault3/enable THP 10519 ± 3% -20.5% 8368 ±6% will-it-scale.per_thread_ops > page_fault2/enalbe THP 8281 ± 2% -18.8% 6728 will-it-scale.per_thread_ops > brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops > context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops > context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops > > b). Disable THP > page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops > page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops > brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops > context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops > brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops > page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops > context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops > > > Best regards, > Haiyan Song > ________________________________________ > From: Laurent Dufour [ldufour@xxxxxxxxxxxxxxxxxx] > Sent: Monday, July 02, 2018 4:59 PM > To: Song, HaiyanX > Cc: 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; linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; haren@xxxxxxxxxxxxxxxxxx; npiggin@xxxxxxxxx; bsingharora@xxxxxxxxx; paulmck@xxxxxxxxxxxxxxxxxx; Tim Chen; linuxppc-dev@xxxxxxxxxxxxxxxx; x86@xxxxxxxxxx > Subject: Re: [PATCH v11 00/26] Speculative page faults > > On 11/06/2018 09:49, Song, HaiyanX wrote: >> Hi Laurent, >> >> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance) >> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on >> V9 patch serials. >> >> The regression result is sorted by the metric will-it-scale.per_thread_ops. >> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126 >> commit id: >> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12 >> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1 >> Benchmark: will-it-scale >> Download link: https://github.com/antonblanchard/will-it-scale/tree/master >> >> 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). Enable THP >> testcase base change head metric >> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops >> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops >> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops >> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops >> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops >> >> b). Disable THP >> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops >> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops >> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops >> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops >> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops >> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops >> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops >> >> Notes: for the above values of test result, the higher is better. > > I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't > get reproducible results. The results have huge variation, even on the vanilla > kernel, and I can't state on any changes due to that. > > I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't > measure any changes between the vanilla and the SPF patched ones: > > test THP enabled 4.17.0-rc4-mm1 spf delta > page_fault3_threads 2697.7 2683.5 -0.53% > page_fault2_threads 170660.6 169574.1 -0.64% > context_switch1_threads 6915269.2 6877507.3 -0.55% > context_switch1_processes 6478076.2 6529493.5 0.79% > brk1 243391.2 238527.5 -2.00% > > Tests were run 10 times, no high variation detected. > > Did you see high variation on your side ? How many times the test were run to > compute the average values ? > > Thanks, > Laurent. > > >> >> 2. Improvement: not found improvement based on the selected test cases. >> >> >> Best regards >> Haiyan Song >> ________________________________________ >> From: owner-linux-mm@xxxxxxxxx [owner-linux-mm@xxxxxxxxx] on behalf of Laurent Dufour [ldufour@xxxxxxxxxxxxxxxxxx] >> Sent: Monday, May 28, 2018 4:54 PM >> To: Song, HaiyanX >> Cc: 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; linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; haren@xxxxxxxxxxxxxxxxxx; npiggin@xxxxxxxxx; bsingharora@xxxxxxxxx; paulmck@xxxxxxxxxxxxxxxxxx; Tim Chen; linuxppc-dev@xxxxxxxxxxxxxxxx; x86@xxxxxxxxxx >> Subject: Re: [PATCH v11 00/26] Speculative page faults >> >> 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 >>>>> >>>>> >>>> >>> >> > >
