On Mon, Jun 11, 2018 at 05:15:22PM +0200, Laurent Dufour wrote: Hi Laurent, For perf date tested on Intel 4s Skylake platform, here attached the compare result between base and head commit in attachment, which include the perf-profile comparision information. And also attached some perf-profile.json captured from test result for page_fault2 and page_fault3 for checking the regression, thanks. Best regards, Haiyan Song > Hi Haiyan, > > I don't have access to the same hardware you ran the test on, but I give a try > to those test on a Power8 system (2 sockets, 5 cores/s, 8 threads/c, 80 CPUs 32G). > I run each will-it-scale test 10 times and compute the average. > > 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% > rk1 243391.2 238527.5 -2.00% > > Test were launched with the arguments '-t 80 -s 5', only the average report is > taken in account. Note that page size is 64K by default on ppc64. > > It would be nice if you could capture some perf data to figure out why the > page_fault2/3 are showing such a performance regression. > > Thanks, > Laurent. > > 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% 8368 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. > > > > 2. Improvement: not found improvement based on the selected test cases. > > > > > > Best regards > > Haiyan Song > > ________________________________________ > > From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com] > > Sent: Monday, May 28, 2018 4:54 PM > > To: Song, HaiyanX > > Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org > > 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@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com] > >>>> Sent: Thursday, May 17, 2018 7:06 PM > >>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; 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@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org > >>>> 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:*' > >>>> > >>>> 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 '. 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 > >>>> > >>>> > >>> > >> > > >