Date:	Tue, 15 Jan 2013 11:10:35 +0800
From:	Michael Wang <wangyun@...ux.vnet.ibm.com>
To:	Mike Galbraith <bitbucket@...ine.de>
CC:	linux-kernel@...r.kernel.org, mingo@...hat.com,
	peterz@...radead.org, mingo@...nel.org, a.p.zijlstra@...llo.nl
Subject: Re: [RFC PATCH 0/2] sched: simplify the select_task_rq_fair()

On 01/14/2013 05:21 PM, Mike Galbraith wrote:
> On Sat, 2013-01-12 at 11:19 +0100, Mike Galbraith wrote:
> 
>> Hm, low end takes a big hit.
> 
> Bah, that's perturbations and knobs.
> 
> aim7 compute, three individual runs + average
> 
> Stock scheduler knobs..
> 
> 3.8-wang                                    avg     3.8-virgin                          avg    vs wang
> Tasks    jobs/min                      jobs/min                                    jobs/min
>     1      435.97    433.48    433.48    434.31        436.91    436.60    434.41    435.97      1.003
>     5     2108.56   2120.36   2153.52   2127.48       2239.47   2257.82   2285.07   2260.78      1.062
>    10     4205.41   4167.81   4294.83   4222.68       4223.00   4199.58   4252.63   4225.07      1.000
>    20     8511.24   8434.24   8614.07   8519.85       8523.21   8505.26   8931.47   8653.31      1.015
>    40    13209.81   6389.04   5308.80   8302.55      13011.27  13131.09  13788.40  13310.25      1.603
>    80    12239.33  17797.36  20438.45  16825.04      15380.71  14372.96  14080.74  13921.31       .827
>   160    52638.44  52609.88  37364.16  47537.49      26644.68  44826.63  41703.23  37724.84       .793
>   320   105162.69 111512.36 105909.34 107528.13     102386.48 106141.22 103424.00 103983.90       .967
>   640   207290.22 207623.13 204556.96 206490.10     196673.43 193243.65 190210.89 193375.99       .936
>  1280   329795.92 326739.68 328399.66 328311.75     305867.51 307931.72 305988.17 306595.80       .933
>  2560   414580.44 418156.33 413035.14 415257.30     404000.00 403894.82 402428.02 403440.94       .971
> 
> Twiddled knobs..
> sched_latency_ns = 24ms
> sched_min_granularity_ns = 8ms
> sched_wakeup_granularity_ns = 10ms
> 
> 3.8-wang                                    avg     3.8-virgin                          avg    vs wang
> Tasks    jobs/min                      jobs/min                                    jobs/min
>     1      437.23    437.23    436.91    437.12        437.86    439.45    438.18    438.49      1.003
>     5     2102.71   2121.85   2130.80   2118.45       2223.04   2165.83   2314.74   2234.53      1.054
>    10     4282.69   4252.63   4378.61   4304.64       4310.10   4303.98   4310.10   4308.06      1.000
>    20     8675.73   8650.96   8725.70   8684.13       8595.74   8638.63   8725.70   8653.35       .996
>    40    16546.08  16512.26  16546.08  16534.80      17022.47  16798.34  16717.24  16846.01      1.018
>    80    32712.55  32602.56  32493.30  32602.80      33137.39  33137.39  32890.09  33054.95      1.013
>   160    63372.55  63125.00  63663.82  63387.12      64510.98  64382.47  64084.60  64326.01      1.014
>   320   121885.61 122656.55 121503.76 122015.30     121124.30 121885.61 121732.58 121580.83       .996
>   640   218010.12 216066.85 217034.14 217037.03     213450.74 212864.98 212282.43 212866.05       .980
>  1280   332339.33 332197.00 332624.36 332386.89     325915.97 325505.67 325232.70 325551.44       .979
>  2560   426901.49 426666.67 427254.20 426940.78     424448.70 425263.16 424564.86 424758.90       .994
> 
> Much better, ~no difference between kernels for this load.

Thanks for the testing, could you please tell me which benchmark
generate these results?

I will try to re-base the patch into 3.8-rc3 with consideration of NUMA
domain, I suppose it could fix the below BUG and provide a better results.

Regards,
Michael Wang

> 
> Except patched 3.8-rc3 kernel crashes on reboot. 
> 
> Please stand by while rebooting the system...
> [  123.104064] kvm: exiting hardware virtualization
> [  123.302908] Disabling[  124.729877] BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
> [  124.758804] IP: [<ffffffff810821f6>] wake_affine+0x26/0x2f0
> [  124.785634] PGD e7089b067 PUD e736f7067 PMD 0 
> [  124.810176] Oops: 0000 [#1] SMP 
> [  124.829767] Modules linked in: iptable_filter ip_tables x_tables nfsv3 nfs_acl nfs fscache lockd sunrpc autofs4 edd af_packet cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf fuse loop dm_mod coretemp kvm_intel iTCO_wdt kvm iTCO_vendor_support i7core_edac igb ioatdma lpc_ich tpm_tis ptp crc32c_intel ipv6 joydev edac_core mfd_core pps_core dca microcode tpm hid_generic i2c_i801 tpm_bios ehci_pci acpi_memhotplug sr_mod container pcspkr sg cdrom button rtc_cmos ext3 jbd mbcache mgag200 ttm drm_kms_helper drm i2c_algo_bit sysimgblt sysfillrect i2c_core syscopyarea usbhid hid uhci_hcd ehci_hcd usbcore usb_common sd_mod crc_t10dif processor thermal_sys hwmon scsi_dh_alua scsi_dh_rdac scsi_dh_hp_sw scsi_dh_emc scsi_dh ata_generic ata_piix libata megaraid_sas scsi_mod
> [  125.093116] CPU 36 
> [  125.097498] Pid: 0, comm: swapper/36 Not tainted 3.8.0-wang #58 QCI QSSC-S4R/QSSC-S4R
> [  125.148934] RIP: 0010:[<ffffffff810821f6>]  [<ffffffff810821f6>] wake_affine+0x26/0x2f0
> [  125.183856] RSP: 0018:ffff88046d9dfc70  EFLAGS: 00010082
> [  125.213390] RAX: 0000000000000001 RBX: 0000000000000024 RCX: 0000000000000046
> [  125.247203] RDX: 0000000000000000 RSI: ffff88046d946280 RDI: 0000000000000000
> [  125.280734] RBP: ffff88046d9dfce8 R08: 0000000000000000 R09: 0000000000000000
> [  125.317137] R10: 0000000000000000 R11: 0000000000000001 R12: ffff88046fa53980
> [  125.354487] R13: 0000000000000024 R14: 0000000000000006 R15: ffff88046d946280
> [  125.391549] FS:  0000000000000000(0000) GS:ffff88046fa40000(0000) knlGS:0000000000000000
> [  125.431203] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [  125.465018] CR2: 0000000000000040 CR3: 0000000e712a1000 CR4: 00000000000007e0
> [  125.501827] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [  125.536604] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [  125.570415] Process swapper/36 (pid: 0, threadinfo ffff88046d9de000, task ffff88046d9dc580)
> [  125.606630] Stack:
> [  125.629700]  ffffffff810895d9 ffff88046d9dfc88 ffff88046fc52f70 000000006d9462c8
> [  125.664431]  0000000000000000 ffff88046d9dfcc8 ffffffff8108a004 ffff88046d9dfce8
> [  125.699339]  ffffffff81086134 000000246d9dfcd8 0000000000000024 ffff88046fa53980
> [  125.734981] Call Trace:
> [  125.758061]  [<ffffffff810895d9>] ? enqueue_entity+0x229/0xa40
> [  125.790423]  [<ffffffff8108a004>] ? enqueue_task_fair+0x214/0x560
> [  125.823023]  [<ffffffff81086134>] ? select_idle_sibling+0xf4/0x120
> [  125.856434]  [<ffffffff810863a9>] select_task_rq_fair+0x249/0x280
> [  125.892564]  [<ffffffff8102d056>] ? native_apic_msr_write+0x36/0x40
> [  125.925262]  [<ffffffff8107fbbb>] try_to_wake_up+0x12b/0x2b0
> [  125.956939]  [<ffffffff8107fd4d>] default_wake_function+0xd/0x10
> [  125.989521]  [<ffffffff8106d031>] autoremove_wake_function+0x11/0x40
> [  126.022899]  [<ffffffff81075e1a>] __wake_up_common+0x5a/0x90
> [  126.054874]  [<ffffffff810794a3>] __wake_up+0x43/0x70
> [  126.085086]  [<ffffffff810e2869>] force_quiescent_state+0xe9/0x130
> [  126.117469]  [<ffffffff810e420e>] rcu_prepare_for_idle+0x27e/0x480
> [  126.150317]  [<ffffffff810e444d>] rcu_eqs_enter_common+0x3d/0x100
> [  126.182428]  [<ffffffff810e4642>] rcu_idle_enter+0x92/0xe0
> [  126.213041]  [<ffffffff8100abd8>] cpu_idle+0x78/0xd0
> [  126.242939]  [<ffffffff8149bcce>] start_secondary+0x7a/0x7c
> [  126.273874] Code: 00 00 00 00 00 55 48 89 e5 48 83 ec 78 4c 89 7d f8 89 55 a4 49 89 f7 48 89 5d d8 4c 89 65 e0 4c 89 6d e8 4c 89 75 f0 48 89 7d a8 <8b> 47 40 65 44 8b 04 25 20 b0 00 00 89 45 c8 48 8b 46 08 48 c7 
> [  126.358480] RIP  [<ffffine+0x26/0x2f0[  126.392023]  RSP <ffff88046d9dfc70>
> [  126.422108] CR2: 0000000000000040
> 
> 

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