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Date: Wed, 20 Feb 2013 01:08:30 +1300 From: Paul Turner <pjt@...gle.com> To: Alex Shi <alex.shi@...el.com> Cc: torvalds@...ux-foundation.org, mingo@...hat.com, peterz@...radead.org, tglx@...utronix.de, akpm@...ux-foundation.org, arjan@...ux.intel.com, bp@...en8.de, namhyung@...nel.org, efault@....de, vincent.guittot@...aro.org, gregkh@...uxfoundation.org, preeti@...ux.vnet.ibm.com, viresh.kumar@...aro.org, linux-kernel@...r.kernel.org, morten.rasmussen@....com Subject: Re: [patch v5 0/15] power aware scheduling FYI I'm currently out of the country in New Zealand and won't be able to take a proper look at this until the beginning of March. On Mon, Feb 18, 2013 at 6:07 PM, Alex Shi <alex.shi@...el.com> wrote: > Since the simplification of fork/exec/wake balancing has much arguments, > I removed that part in the patch set. > > This patch set implement/consummate the rough power aware scheduling > proposal: https://lkml.org/lkml/2012/8/13/139. > It defines 2 new power aware policy 'balance' and 'powersaving', then > try to pack tasks on each sched groups level according the different > scheduler policy. That can save much power when task number in system > is no more than LCPU number. > > As mentioned in the power aware scheduling proposal, Power aware > scheduling has 2 assumptions: > 1, race to idle is helpful for power saving > 2, less active sched groups will reduce cpu power consumption > > The first assumption make performance policy take over scheduling when > any group is busy. > The second assumption make power aware scheduling try to pack disperse > tasks into fewer groups. > > Like sched numa, power aware scheduling is also a kind of cpu locality > oriented scheduling, so it is natural compatible with sched numa. > > Since the patch can perfect pack tasks into fewer groups, I just show > some performance/power testing data here: > ========================================= > $for ((i = 0; i < I; i++)) ; do while true; do :; done & done > > On my SNB laptop with 4core* HT: the data is avg Watts > powersaving balance performance > i = 2 40 54 54 > i = 4 57 64* 68 > i = 8 68 68 68 > > Note: > When i = 4 with balance policy, the power may change in 57~68Watt, > since the HT capacity and core capacity are both 1. > > on SNB EP machine with 2 sockets * 8 cores * HT: > powersaving balance performance > i = 4 190 201 238 > i = 8 205 241 268 > i = 16 271 348 376 > > bltk-game with openarena, the data is avg Watts > powersaving balance performance > wsm laptop 22.9 23.8 24.4 > snb laptop 20.2 20.5 20.7 > > tasks number keep waving benchmark, 'make -j x vmlinux' > on my SNB EP 2 sockets machine with 8 cores * HT: > > powersaving balance performance > x = 1 175.603 /417 13 175.220 /416 13 176.073 /407 13 > x = 2 192.215 /218 23 194.522 /202 25 217.393 /200 23 > x = 4 205.226 /124 39 208.823 /114 42 230.425 /105 41 > x = 8 236.369 /71 59 249.005 /65 61 257.661 /62 62 > x = 16 283.842 /48 73 307.465 /40 81 309.336 /39 82 > x = 32 325.197 /32 96 333.503 /32 93 336.138 /32 92 > > data explains: 175.603 /417 13 > 175.603: average Watts > 417: seconds(compile time) > 13: scaled performance/power = 1000000 / seconds / watts > > Another testing of parallel compress with pigz on Linus' git tree. > results show we get much better performance/power with powersaving and > balance policy: > > testing command: > #pigz -k -c -p$x -r linux* &> /dev/null > > On a NHM EP box > powersaving balance performance > x = 4 166.516 /88 68 170.515 /82 71 165.283 /103 58 > x = 8 173.654 /61 94 177.693 /60 93 172.31 /76 76 > > On a 2 sockets SNB EP box. > powersaving balance performance > x = 4 190.995 /149 35 200.6 /129 38 208.561 /135 35 > x = 8 197.969 /108 46 208.885 /103 46 213.96 /108 43 > x = 16 205.163 /76 64 212.144 /91 51 229.287 /97 44 > > data format is: 166.516 /88 68 > 166.516: average Watts > 88: seconds(compress time) > 68: scaled performance/power = 1000000 / time / power > > Some performance testing results: > --------------------------------- > > Tested benchmarks: kbuild, specjbb2005, oltp, tbench, aim9, > hackbench, fileio-cfq of sysbench, dbench, aiostress, multhreads > loopback netperf. on my core2, nhm, wsm, snb, platforms. no clear > performance change found on 'performance' policy. > > Tested balance/powersaving policy with above benchmarks, > a, specjbb2005 drop 5~7% on both of policy whenever with openjdk or jrockit. > b, hackbench drops 30+% with powersaving policy on snb 4 sockets platforms. > Others has no clear change. > > test result from Mike Galbraith: > -------------------------------- > With aim7 compute on 4 node 40 core box, I see stable throughput > improvement at tasks = nr_cores and below w. balance and powersaving. > > 3.8.0-performance 3.8.0-balance 3.8.0-powersaving > Tasks jobs/min/task jobs/min/task jobs/min/task > 1 432.8571 433.4764 433.1665 > 5 480.1902 510.9612 497.5369 > 10 429.1785 533.4507 518.3918 > 20 424.3697 529.7203 528.7958 > 40 419.0871 500.8264 517.0648 > > No deltas after that. There were also no deltas between patched kernel > using performance policy and virgin source. > > > Changelog: > V5 change: > a, change sched_policy to sched_balance_policy > b, split fork/exec/wake power balancing into 3 patches and refresh > commit logs > c, others minors clean up > > V4 change: > a, fix few bugs and clean up code according to Morten Rasmussen, Mike > Galbraith and Namhyung Kim. Thanks! > b, take Morten Rasmussen's suggestion to use different criteria for > different policy in transitory task packing. > c, shorter latency in power aware scheduling. > > V3 change: > a, engaged nr_running and utils in periodic power balancing. > b, try packing small exec/wake tasks on running cpu not idle cpu. > > V2 change: > a, add lazy power scheduling to deal with kbuild like benchmark. > > > Thanks comments/suggestions from PeterZ, Linus Torvalds, Andrew Morton, > Ingo, Arjan van de Ven, Borislav Petkov, PJT, Namhyung Kim, Mike > Galbraith, Greg, Preeti, Morten Rasmussen etc. > > Thanks fengguang's 0-day kbuild system for testing this patchset. > > Any more comments are appreciated! > > -- Thanks Alex > > > [patch v5 01/15] sched: set initial value for runnable avg of sched > [patch v5 02/15] sched: set initial load avg of new forked task > [patch v5 03/15] Revert "sched: Introduce temporary FAIR_GROUP_SCHED > [patch v5 04/15] sched: add sched balance policies in kernel > [patch v5 05/15] sched: add sysfs interface for sched_balance_policy > [patch v5 06/15] sched: log the cpu utilization at rq > [patch v5 07/15] sched: add new sg/sd_lb_stats fields for incoming > [patch v5 08/15] sched: move sg/sd_lb_stats struct ahead > [patch v5 09/15] sched: add power aware scheduling in fork/exec/wake > [patch v5 10/15] sched: packing transitory tasks in wake/exec power > [patch v5 11/15] sched: add power/performance balance allow flag > [patch v5 12/15] sched: pull all tasks from source group > [patch v5 13/15] sched: no balance for prefer_sibling in power > [patch v5 14/15] sched: power aware load balance > [patch v5 15/15] sched: lazy power balance -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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