[PATCH v11 00/26] Speculative page faults
Song, HaiyanX
haiyanx.song at intel.com
Wed Jul 4 13:23:14 AEST 2018
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.
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 at linux.vnet.ibm.com]
Sent: Monday, July 02, 2018 4:59 PM
To: Song, HaiyanX
Cc: akpm at linux-foundation.org; mhocko at kernel.org; peterz at infradead.org; kirill at shutemov.name; ak at linux.intel.com; dave at stgolabs.net; jack at suse.cz; Matthew Wilcox; khandual at linux.vnet.ibm.com; aneesh.kumar at linux.vnet.ibm.com; benh at kernel.crashing.org; mpe at ellerman.id.au; paulus at samba.org; Thomas Gleixner; Ingo Molnar; hpa at zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work at 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 at vger.kernel.org; linux-mm at kvack.org; haren at linux.vnet.ibm.com; npiggin at gmail.com; bsingharora at gmail.com; paulmck at linux.vnet.ibm.com; Tim Chen; linuxppc-dev at lists.ozlabs.org; x86 at kernel.org
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 at kvack.org [owner-linux-mm at kvack.org] on behalf of Laurent Dufour [ldufour at linux.vnet.ibm.com]
> Sent: Monday, May 28, 2018 4:54 PM
> To: Song, HaiyanX
> Cc: akpm at linux-foundation.org; mhocko at kernel.org; peterz at infradead.org; kirill at shutemov.name; ak at linux.intel.com; dave at stgolabs.net; jack at suse.cz; Matthew Wilcox; khandual at linux.vnet.ibm.com; aneesh.kumar at linux.vnet.ibm.com; benh at kernel.crashing.org; mpe at ellerman.id.au; paulus at samba.org; Thomas Gleixner; Ingo Molnar; hpa at zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work at 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 at vger.kernel.org; linux-mm at kvack.org; haren at linux.vnet.ibm.com; npiggin at gmail.com; bsingharora at gmail.com; paulmck at linux.vnet.ibm.com; Tim Chen; linuxppc-dev at lists.ozlabs.org; x86 at 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 at kvack.org [owner-linux-mm at kvack.org] on behalf of Laurent Dufour [ldufour at linux.vnet.ibm.com]
>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>> To: akpm at linux-foundation.org; mhocko at kernel.org; peterz at infradead.org; kirill at shutemov.name; ak at linux.intel.com; dave at stgolabs.net; jack at suse.cz; Matthew Wilcox; khandual at linux.vnet.ibm.com; aneesh.kumar at linux.vnet.ibm.com; benh at kernel.crashing.org; mpe at ellerman.id.au; paulus at samba.org; Thomas Gleixner; Ingo Molnar; hpa at zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work at 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 at vger.kernel.org; linux-mm at kvack.org; haren at linux.vnet.ibm.com; npiggin at gmail.com; bsingharora at gmail.com; paulmck at linux.vnet.ibm.com; Tim Chen; linuxppc-dev at lists.ozlabs.org; x86 at 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:*' <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
>>>>
>>>>
>>>
>>
>
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