From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp08.au.ibm.com (e23smtp08.au.ibm.com [202.81.31.141]) (using TLSv1.2 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3qs4Nf4TF8zDq5g for ; Sat, 23 Apr 2016 04:47:13 +1000 (AEST) Received: from localhost by e23smtp08.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sat, 23 Apr 2016 03:36:46 +1000 Received: from d23relay07.au.ibm.com (d23relay07.au.ibm.com [9.190.26.37]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id 3135A3578053 for ; Sat, 23 Apr 2016 03:36:45 +1000 (EST) Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay07.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u3MHaavQ8061234 for ; Sat, 23 Apr 2016 03:36:45 +1000 Received: from d23av03.au.ibm.com (localhost [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u3MHZwEM005743 for ; Sat, 23 Apr 2016 03:35:58 +1000 From: Akshay Adiga Subject: Re: [PATCH v2 2/2] cpufreq: powernv: Ramp-down global pstate slower than local-pstate To: Stewart Smith , rjw@rjwysocki.net, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <1460701739-31549-1-git-send-email-akshay.adiga@linux.vnet.ibm.com> <1460701739-31549-3-git-send-email-akshay.adiga@linux.vnet.ibm.com> <87vb3dmep8.fsf@linux.vnet.ibm.com> Cc: ego@linux.vnet.ibm.com Message-ID: <571A60EB.5030603@linux.vnet.ibm.com> Date: Fri, 22 Apr 2016 23:05:39 +0530 MIME-Version: 1.0 In-Reply-To: <87vb3dmep8.fsf@linux.vnet.ibm.com> Content-Type: multipart/alternative; boundary="------------080902020909030002000208" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , This is a multi-part message in MIME format. --------------080902020909030002000208 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Hi Stewart, On 04/20/2016 03:41 AM, Stewart Smith wrote: > Akshay Adiga writes: >> Iozone results show fairly consistent performance boost. >> YCSB on redis shows improved Max latencies in most cases. > What about power consumption? > >> Iozone write/rewite test were made with filesizes 200704Kb and 401408Kb >> with different record sizes . The following table shows IOoperations/sec >> with and without patch. >> Iozone Results ( in op/sec) ( mean over 3 iterations ) > What's the variance between runs? Re-Ran Iozone test w/o : without patch, w : with patch , stdev : standard deviation , avg ; average Iozone Results for ReWrite +----------+--------+-----------+------------+-----------+-----------+---------+ | filesize | reclen | w/o(avg) | w/o(stdev) | w(avg) | w(stdev) | change% | +----------+--------+-----------+------------+-----------+-----------+---------+ | 200704 | 1 | 795070.4 | 5813.51 | 805127.8 | 16872.59 | 1.264 | | 200704 | 2 | 1448973.8 | 23058.79 | 1472098.8 | 18062.73 | 1.595 | | 200704 | 4 | 2413444 | 85988.09 | 2562535.8 | 48649.35 | 6.177 | | 200704 | 8 | 3827453 | 87710.52 | 3846888.2 | 86438.51 | 0.507 | | 200704 | 16 | 5276096.8 | 73208.19 | 5425961.6 | 170774.75 | 2.840 | | 200704 | 32 | 6742930.6 | 22789.45 | 6848904.4 | 257768.84 | 1.571 | | 200704 | 64 | 7059479.2 | 300725.26 | 7373635 | 285106.90 | 4.450 | | 200704 | 128 | 7097647.2 | 408171.71 | 7716500 | 266139.68 | 8.719 | | 200704 | 256 | 6710810 | 314594.13 | 7661752.6 | 454049.27 | 14.170 | | 200704 | 512 | 7034675.4 | 516152.97 | 7378583.2 | 613617.57 | 4.888 | | 200704 | 1024 | 6265317.2 | 446101.38 | 7540629.6 | 294865.20 | 20.355 | | 401408 | 1 | 802233.2 | 4263.92 | 817507 | 17727.09 | 1.903 | | 401408 | 2 | 1461892.8 | 53678.12 | 1482872 | 45670.30 | 1.435 | | 401408 | 4 | 2629686.8 | 24365.33 | 2673196.2 | 41576.78 | 1.654 | | 401408 | 8 | 4156353.8 | 70636.85 | 4149330.4 | 56521.84 | -0.168 | | 401408 | 16 | 5895437 | 63762.43 | 5924167.4 | 396311.75 | 0.487 | | 401408 | 32 | 7330826.6 | 167080.53 | 7785889.2 | 245434.99 | 6.207 | | 401408 | 64 | 8298555.2 | 328890.89 | 8482416.8 | 249698.02 | 2.215 | | 401408 | 128 | 8241108.6 | 490560.96 | 8686478 | 224816.21 | 5.404 | | 401408 | 256 | 8038080.6 | 327704.66 | 8372327.4 | 210978.18 | 4.158 | | 401408 | 512 | 8229523.4 | 371701.73 | 8654695.2 | 296715.07 | 5.166 | +----------+--------+-----------+------------+-----------+-----------+---------+ Iozone results for Write +----------+--------+-----------+------------+-----------+------------+---------+ | filesize | reclen | w/o(avg) | w/o(stdev) | w(avg) | w(stdev) | change% | +----------+--------+-----------+------------+-----------+------------+---------+ | 200704 | 1 | 575825 | 7,876.69 | 569388.4 | 6,699.59 | -1.12 | | 200704 | 2 | 1061229.4 | 7,589.50 | 1045193.2 | 19,785.85 | -1.51 | | 200704 | 4 | 1808329 | 13,040.67 | 1798138.4 | 50,367.19 | -0.56 | | 200704 | 8 | 2822953.4 | 19,948.89 | 2830305.6 | 21,202.77 | 0.26 | | 200704 | 16 | 3976987 | 62,201.72 | 3909063.8 | 268,640.51 | -1.71 | | 200704 | 32 | 4959358.2 | 112,052.99 | 4760303 | 330,343.73 | -4.01 | | 200704 | 64 | 5452454.6 | 628,078.72 | 5692265.6 | 190,562.91 | 4.40 | | 200704 | 128 | 5645246.8 | 10,455.85 | 5653330.2 | 18,153.76 | 0.14 | | 200704 | 256 | 5855897.2 | 184,854.25 | 5402069 | 538,523.04 | -7.75 | | 200704 | 512 | 5515904 | 326,198.86 | 5639976.4 | 8,480.46 | 2.25 | | 200704 | 1024 | 5471718.2 | 415,179.15 | 5399414.6 | 686,124.50 | -1.32 | | 401408 | 1 | 584786.6 | 1,256.59 | 587237.2 | 6,552.55 | 0.42 | | 401408 | 2 | 1047018.8 | 26,567.72 | 1040926.8 | 16,495.93 | -0.58 | | 401408 | 4 | 1815465.8 | 16,426.92 | 1773652.6 | 38,169.02 | -2.30 | | 401408 | 8 | 2814285 | 27,374.53 | 2756608 | 96,689.13 | -2.05 | | 401408 | 16 | 3931646 | 129,648.79 | 3805793.4 | 141,368.40 | -3.20 | | 401408 | 32 | 4875353.4 | 146,203.70 | 4884084 | 265,484.01 | 0.18 | | 401408 | 64 | 5479805.8 | 349,995.36 | 5565292.2 | 20,645.45 | 1.56 | | 401408 | 128 | 5598486 | 195,680.23 | 5645125 | 62,017.38 | 0.83 | | 401408 | 256 | 5803148 | 328,683.02 | 5657215 | 20,579.28 | -2.51 | | 401408 | 512 | 5565091.4 | 166,123.57 | 5725974.4 | 169,506.29 | 2.89 | +----------+--------+-----------+------------+-----------+------------+---------+ >> Tested with YCSB workload (50% update + 50% read) over redis for 1 million >> records and 1 million operation. Each test was carried out with target >> operations per second and persistence disabled. >> >> Max-latency (in us)( mean over 5 iterations ) > What's the variance between runs? > > std dev? 95th percentile? > >> --------------------------------------------------------------- >> op/s Operation with patch without patch %change >> --------------------------------------------------------------- >> 15000 Read 61480.6 50261.4 22.32 > This seems fairly significant regression. Any idea why at 15K op/s > there's such a regression? Just Re-Ran the test for power numbers. Results for YCSB+Redis test. P95 : 95 Percentile P99 : 99 Percentile Power numbers are taken for one run of YCSB+redis test which has 50% Read + 50% Update. Maximum Latency has clearly gone down for all cases will less than 5% increase in power. +------------+----------+--------+------------+---------+---------+----------------+ | Op/sec | Testcase | AvgLat | MaxLat | P95 | P99 | Power | +------------+----------+--------+------------+---------+---------+----------------+ | 15000 | Read | - | - | - | - | - | | w/o patch | Average | 51.8 | 127903.0 | 55.8 | 145.2 | 602.7 | | w/o patch | StdDev | 5.692 | 105355.497 | 11.232 | 2.04 | 5.11 | | with patch | Average | 53.28 | 30834.2 | 72.2 | 151.2 | 629.01 | | with patch | StdDev | 2.348 | 8928.323 | 15.74 | 3.544 | 3.25 | | - |*Change% | 2.86 | -75.89 | 29.39 | 4.13 | 4.36535589846* | | 25000 | Read | - | - | - | - | - | | w/o patch | Average | 53.78 | 123743.0 | 85.4 | 152.2 | 617.95 | | w/o patch | StdDev | 4.593 | 80224.53 | 5.886 | 4.49 | 1.32 | | with patch | Average | 49.65 | 84101.4 | 84.2 | 154.4 | 651.64 | | with patch | StdDev | 1.658 | 72656.042 | 4.261 | 2.332 | 8.76 | | - |*Change% | -7.68 | -32.04 | -1.41 | 1.45 | 5.4518974027 * | | 35000 | Read | - | - | - | - | - | | w/o patch | Average | 56.07 | 57391.0 | 93.0 | 147.6 | 636.39 | | w/o patch | StdDev | 1.391 | 34494.839 | 1.789 | 2.871 | 2.92 | | with patch | Average | 56.46 | 39634.2 | 95.0 | 149.2 | 653.44 | | with patch | StdDev | 3.174 | 6089.848 | 3.347 | 3.37 | 4.4 | | - |*Change% | 0.69 | -30.94 | 2.15 | 1.08 | 2.6791747199 * | | 40000 | Read | - | - | - | - | - | | w/o patch | Average | 58.6 | 80427.8 | 97.2 | 147.4 | 636.85 | | w/o patch | StdDev | 1.105 | 59327.584 | 0.748 | 2.498 | 1.51 | | with patch | Average | 58.76 | 45291.8 | 97.2 | 149.0 | 656.12 | | with patch | StdDev | 1.675 | 10486.954 | 2.482 | 3.406 | 6.97 | | - |*Change% | 0.27 | -43.69 | 0.0 | 1.09 | 3.0258302583* | | 45000 | Read | - | - | - | - | - | | w/o patch | Average | 69.02 | 120027.8 | 102.6 | 149.6 | 640.68 | | w/o patch | StdDev | 0.74 | 96288.811 | 1.855 | 1.497 | 7.65 | | with patch | Average | 69.65 | 98024.6 | 102.0 | 147.8 | 653.09 | | with patch | StdDev | 1.14 | 78041.439 | 2.28 | 1.939 | 3.91 | | -*| Change% | 0.92 | -18.33 | -0.58 | -1.2 | 1.93700443279* | | 15000 | Update | - | - | - | - | - | | w/o patch | Average | 48.144 | 86847.0 | 52.4 | 189.2 | 602.7 | | w/o patch | StdDev | 5.971 | 41580.919 | 16.427 | 8.376 | 5.11 | | with patch | Average | 47.964 | 31106.2 | 58.4 | 182.2 | 629.01 | | with patch | StdDev | 3.003 | 4906.179 | 7.088 | 6.177 | 3.25 | | - |*Change% | -0.37 | -64.18 | 11.45 | -3.7 | -3.69978858351* | | 25000 | Update | - | - | - | - | - | | w/o patch | Average | 51.856 | 102808.6 | 87.0 | 182.4 | 617.95 | | w/o patch | StdDev | 5.721 | 79308.823 | 4.899 | 7.965 | 1.32 | | with patch | Average | 46.07 | 74623.0 | 86.2 | 183.0 | 651.64 | | with patch | StdDev | 1.779 | 77511.229 | 4.069 | 7.014 | 8.76 | | - |*Change% | -11.16 | -27.42 | -0.92 | 0.33 | 0.328947368421* | | 35000 | Update | - | - | - | - | - | | w/o patch | Average | 54.142 | 51074.2 | 93.6 | 181.8 | 636.39 | | w/o patch | StdDev | 1.671 | 36877.588 | 1.497 | 8.035 | 2.92 | | with patch | Average | 54.034 | 44731.8 | 94.4 | 184.4 | 653.44 | | with patch | StdDev | 3.363 | 13400.4 | 1.02 | 7.172 | 4.4 | | - |*Change% | -0.2 | -12.42 | 0.85 | 1.43 | 1.4301430143* | | 40000 | Update | - | - | - | - | - | | w/o patch | Average | 57.528 | 71672.6 | 98.4 | 184.8 | 636.85 | | w/o patch | StdDev | 1.111 | 63103.862 | 1.744 | 9.282 | 1.51 | | with patch | Average | 57.738 | 32101.4 | 98.0 | 186.4 | 656.12 | | with patch | StdDev | 1.294 | 4481.801 | 1.673 | 7.71 | 6.97 | | - |*Change% | 0.37 | -55.21 | -0.41 | 0.87 | 0.865800865801 *| | 45000 | Update | - | - | - | - | - | | w/o patch | Average | 69.97 | 117183.0 | 105.4 | 182.4 | 640.68 | | w/o patch | StdDev | 0.925 | 99836.076 | 1.2 | 9.091 | 7.65 | | with patch | Average | 70.508 | 104175.0 | 103.2 | 185.4 | 653.09 | | with patch | StdDev | 1.463 | 74438.13 | 1.47 | 7.915 | 3.91 | | - |*Change% | 0.77 | -11.1 | -2.09 | 1.64 | 1.64473684211 *| +------------+----------+--------+------------+---------+---------+----------------+ >> --- a/drivers/cpufreq/powernv-cpufreq.c >> +++ b/drivers/cpufreq/powernv-cpufreq.c >> @@ -36,12 +36,56 @@ >> #include >> #include /* Required for cpu_sibling_mask() in UP configs */ >> #include >> +#include >> >> #define POWERNV_MAX_PSTATES 256 >> #define PMSR_PSAFE_ENABLE (1UL << 30) >> #define PMSR_SPR_EM_DISABLE (1UL << 31) >> #define PMSR_MAX(x) ((x >> 32) & 0xFF) >> >> +#define MAX_RAMP_DOWN_TIME 5120 >> +/* >> + * On an idle system we want the global pstate to ramp-down from max value to >> + * min over a span of ~5 secs. Also we want it to initially ramp-down slowly and >> + * then ramp-down rapidly later on. > Where does 5 seconds come from? > > Why 5 and not 10, or not 2? Is there some time period inherit in > hardware or software that this is computed from? As global pstates are per-chip and there are max 12 cores, so if the system is really idle, considering 5 seconds for each cores, it should take 60 seconds for the chip to go to pmin. >> +/* Interval after which the timer is queued to bring down global pstate */ >> +#define GPSTATE_TIMER_INTERVAL 2000 > in ms? Yes its 2000 ms. --------------080902020909030002000208 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: 8bit 
Hi Stewart,
On 04/20/2016 03:41 AM, Stewart Smith wrote:
Akshay Adiga <akshay.adiga@linux.vnet.ibm.com> writes:

Iozone results show fairly consistent performance boost.
YCSB on redis shows improved Max latencies in most cases.

What about power consumption?


Iozone write/rewite test were made with filesizes 200704Kb and 401408Kb
with different record sizes . The following table shows IOoperations/sec
with and without patch.

Iozone Results ( in op/sec) ( mean over 3 iterations )

What's the variance between runs?

Re-Ran Iozone test

w/o : without patch,  w : with patch , stdev : standard deviation , avg ; average 

Iozone Results for ReWrite
+----------+--------+-----------+------------+-----------+-----------+---------+
| filesize | reclen |  w/o(avg) | w/o(stdev) |   w(avg)  |  w(stdev) | change% |
+----------+--------+-----------+------------+-----------+-----------+---------+
|  200704  |   1    |  795070.4 |  5813.51   |  805127.8 |  16872.59 |  1.264  |
|  200704  |   2    | 1448973.8 |  23058.79  | 1472098.8 |  18062.73 |  1.595  |
|  200704  |   4    |  2413444  |  85988.09  | 2562535.8 |  48649.35 |  6.177  |
|  200704  |   8    |  3827453  |  87710.52  | 3846888.2 |  86438.51 |  0.507  |
|  200704  |   16   | 5276096.8 |  73208.19  | 5425961.6 | 170774.75 |  2.840  |
|  200704  |   32   | 6742930.6 |  22789.45  | 6848904.4 | 257768.84 |  1.571  |
|  200704  |   64   | 7059479.2 | 300725.26  |  7373635  | 285106.90 |  4.450  |
|  200704  |  128   | 7097647.2 | 408171.71  |  7716500  | 266139.68 |  8.719  |
|  200704  |  256   |  6710810  | 314594.13  | 7661752.6 | 454049.27 |  14.170 |
|  200704  |  512   | 7034675.4 | 516152.97  | 7378583.2 | 613617.57 |  4.888  |
|  200704  |  1024  | 6265317.2 | 446101.38  | 7540629.6 | 294865.20 |  20.355 |
|  401408  |   1    |  802233.2 |  4263.92   |   817507  |  17727.09 |  1.903  |
|  401408  |   2    | 1461892.8 |  53678.12  |  1482872  |  45670.30 |  1.435  |
|  401408  |   4    | 2629686.8 |  24365.33  | 2673196.2 |  41576.78 |  1.654  |
|  401408  |   8    | 4156353.8 |  70636.85  | 4149330.4 |  56521.84 |  -0.168 |
|  401408  |   16   |  5895437  |  63762.43  | 5924167.4 | 396311.75 |  0.487  |
|  401408  |   32   | 7330826.6 | 167080.53  | 7785889.2 | 245434.99 |  6.207  |
|  401408  |   64   | 8298555.2 | 328890.89  | 8482416.8 | 249698.02 |  2.215  |
|  401408  |  128   | 8241108.6 | 490560.96  |  8686478  | 224816.21 |  5.404  |
|  401408  |  256   | 8038080.6 | 327704.66  | 8372327.4 | 210978.18 |  4.158  |
|  401408  |  512   | 8229523.4 | 371701.73  | 8654695.2 | 296715.07 |  5.166  |
+----------+--------+-----------+------------+-----------+-----------+---------+

Iozone results for Write 
+----------+--------+-----------+------------+-----------+------------+---------+
| filesize | reclen |  w/o(avg) | w/o(stdev) |   w(avg)  |  w(stdev)  | change% |
+----------+--------+-----------+------------+-----------+------------+---------+
|  200704  |   1    |   575825  |  7,876.69  |  569388.4 |  6,699.59  |  -1.12  |
|  200704  |   2    | 1061229.4 |  7,589.50  | 1045193.2 | 19,785.85  |  -1.51  |
|  200704  |   4    |  1808329  | 13,040.67  | 1798138.4 | 50,367.19  |  -0.56  |
|  200704  |   8    | 2822953.4 | 19,948.89  | 2830305.6 | 21,202.77  |   0.26  |
|  200704  |   16   |  3976987  | 62,201.72  | 3909063.8 | 268,640.51 |  -1.71  |
|  200704  |   32   | 4959358.2 | 112,052.99 |  4760303  | 330,343.73 |  -4.01  |
|  200704  |   64   | 5452454.6 | 628,078.72 | 5692265.6 | 190,562.91 |   4.40  |
|  200704  |  128   | 5645246.8 | 10,455.85  | 5653330.2 | 18,153.76  |   0.14  |
|  200704  |  256   | 5855897.2 | 184,854.25 |  5402069  | 538,523.04 |  -7.75  |
|  200704  |  512   |  5515904  | 326,198.86 | 5639976.4 |  8,480.46  |   2.25  |
|  200704  |  1024  | 5471718.2 | 415,179.15 | 5399414.6 | 686,124.50 |  -1.32  |
|  401408  |   1    |  584786.6 |  1,256.59  |  587237.2 |  6,552.55  |   0.42  |
|  401408  |   2    | 1047018.8 | 26,567.72  | 1040926.8 | 16,495.93  |  -0.58  |
|  401408  |   4    | 1815465.8 | 16,426.92  | 1773652.6 | 38,169.02  |  -2.30  |
|  401408  |   8    |  2814285  | 27,374.53  |  2756608  | 96,689.13  |  -2.05  |
|  401408  |   16   |  3931646  | 129,648.79 | 3805793.4 | 141,368.40 |  -3.20  |
|  401408  |   32   | 4875353.4 | 146,203.70 |  4884084  | 265,484.01 |   0.18  |
|  401408  |   64   | 5479805.8 | 349,995.36 | 5565292.2 | 20,645.45  |   1.56  |
|  401408  |  128   |  5598486  | 195,680.23 |  5645125  | 62,017.38  |   0.83  |
|  401408  |  256   |  5803148  | 328,683.02 |  5657215  | 20,579.28  |  -2.51  |
|  401408  |  512   | 5565091.4 | 166,123.57 | 5725974.4 | 169,506.29 |   2.89  |
+----------+--------+-----------+------------+-----------+------------+---------+



      

        
Tested with YCSB workload (50% update + 50% read) over redis for 1 million
records and 1 million operation. Each test was carried out with target
operations per second and persistence disabled.

Max-latency (in us)( mean over 5 iterations )


      

      
What's the variance between runs?

std dev? 95th percentile?



      

        
---------------------------------------------------------------
op/s    Operation       with patch      without patch   %change
---------------------------------------------------------------
15000   Read            61480.6         50261.4         22.32


      

      
This seems fairly significant regression. Any idea why at 15K op/s
there's such a regression?


    

    
Just Re-Ran the test for power numbers. 
Results for YCSB+Redis test.
P95 : 95 Percentile 
P99 : 99 Percentile

Power numbers are taken for one run of YCSB+redis test which has 50% Read + 50% Update.
Maximum Latency has clearly gone down for all cases will less than 5% increase in power.


+------------+----------+--------+------------+---------+---------+----------------+
|   Op/sec   | Testcase | AvgLat |   MaxLat   |   P95   |   P99   |     Power      |
+------------+----------+--------+------------+---------+---------+----------------+
|   15000    |   Read   |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  |  51.8  |  127903.0  |   55.8  |  145.2  |     602.7      |
| w/o patch  |  StdDev  | 5.692  | 105355.497 |  11.232 |   2.04  |      5.11      |
| with patch | Average  | 53.28  |  30834.2   |   72.2  |  151.2  |     629.01     |
| with patch |  StdDev  | 2.348  |  8928.323  |  15.74  |  3.544  |      3.25      |
|     -      | Change%  |  2.86  |   -75.89   |  29.39  |   4.13  | 4.36535589846  |
|   25000    |   Read   |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  | 53.78  |  123743.0  |   85.4  |  152.2  |     617.95     |
| w/o patch  |  StdDev  | 4.593  |  80224.53  |  5.886  |   4.49  |      1.32      |
| with patch | Average  | 49.65  |  84101.4   |   84.2  |  154.4  |     651.64     |
| with patch |  StdDev  | 1.658  | 72656.042  |  4.261  |  2.332  |      8.76      |
|     -      | Change%  | -7.68  |   -32.04   |  -1.41  |   1.45  |  5.4518974027  |
|   35000    |   Read   |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  | 56.07  |  57391.0   |   93.0  |  147.6  |     636.39     |
| w/o patch  |  StdDev  | 1.391  | 34494.839  |  1.789  |  2.871  |      2.92      |
| with patch | Average  | 56.46  |  39634.2   |   95.0  |  149.2  |     653.44     |
| with patch |  StdDev  | 3.174  |  6089.848  |  3.347  |   3.37  |      4.4       |
|     -      | Change%  |  0.69  |   -30.94   |   2.15  |   1.08  |  2.6791747199  |
|   40000    |   Read   |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  |  58.6  |  80427.8   |   97.2  |  147.4  |     636.85     |
| w/o patch  |  StdDev  | 1.105  | 59327.584  |  0.748  |  2.498  |      1.51      |
| with patch | Average  | 58.76  |  45291.8   |   97.2  |  149.0  |     656.12     |
| with patch |  StdDev  | 1.675  | 10486.954  |  2.482  |  3.406  |      6.97      |
|     -      | Change%  |  0.27  |   -43.69   |   0.0   |   1.09  |  3.0258302583  |
|   45000    |   Read   |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  | 69.02  |  120027.8  |  102.6  |  149.6  |     640.68     |
| w/o patch  |  StdDev  |  0.74  | 96288.811  |  1.855  |  1.497  |      7.65      |
| with patch | Average  | 69.65  |  98024.6   |  102.0  |  147.8  |     653.09     |
| with patch |  StdDev  |  1.14  | 78041.439  |   2.28  |  1.939  |      3.91      |
|     -      | Change%  |  0.92  |   -18.33   |  -0.58  |   -1.2  | 1.93700443279  |
|   15000    |  Update  |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  | 48.144 |  86847.0   |   52.4  |  189.2  |     602.7      |
| w/o patch  |  StdDev  | 5.971  | 41580.919  |  16.427 |  8.376  |      5.11      |
| with patch | Average  | 47.964 |  31106.2   |   58.4  |  182.2  |     629.01     |
| with patch |  StdDev  | 3.003  |  4906.179  |  7.088  |  6.177  |      3.25      |
|     -      | Change%  | -0.37  |   -64.18   |  11.45  |   -3.7  | -3.69978858351 |
|   25000    |  Update  |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  | 51.856 |  102808.6  |   87.0  |  182.4  |     617.95     |
| w/o patch  |  StdDev  | 5.721  | 79308.823  |  4.899  |  7.965  |      1.32      |
| with patch | Average  | 46.07  |  74623.0   |   86.2  |  183.0  |     651.64     |
| with patch |  StdDev  | 1.779  | 77511.229  |  4.069  |  7.014  |      8.76      |
|     -      | Change%  | -11.16 |   -27.42   |  -0.92  |   0.33  | 0.328947368421 |
|   35000    |  Update  |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  | 54.142 |  51074.2   |   93.6  |  181.8  |     636.39     |
| w/o patch  |  StdDev  | 1.671  | 36877.588  |  1.497  |  8.035  |      2.92      |
| with patch | Average  | 54.034 |  44731.8   |   94.4  |  184.4  |     653.44     |
| with patch |  StdDev  | 3.363  |  13400.4   |   1.02  |  7.172  |      4.4       |
|     -      | Change%  |  -0.2  |   -12.42   |   0.85  |   1.43  |  1.4301430143  |
|   40000    |  Update  |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  | 57.528 |  71672.6   |   98.4  |  184.8  |     636.85     |
| w/o patch  |  StdDev  | 1.111  | 63103.862  |  1.744  |  9.282  |      1.51      |
| with patch | Average  | 57.738 |  32101.4   |   98.0  |  186.4  |     656.12     |
| with patch |  StdDev  | 1.294  |  4481.801  |  1.673  |   7.71  |      6.97      |
|     -      | Change%  |  0.37  |   -55.21   |  -0.41  |   0.87  | 0.865800865801 |
|   45000    |  Update  |   -    |     -      |    -    |    -    |       -        |
| w/o patch  | Average  | 69.97  |  117183.0  |  105.4  |  182.4  |     640.68     |
| w/o patch  |  StdDev  | 0.925  | 99836.076  |   1.2   |  9.091  |      7.65      |
| with patch | Average  | 70.508 |  104175.0  |  103.2  |  185.4  |     653.09     |
| with patch |  StdDev  | 1.463  |  74438.13  |   1.47  |  7.915  |      3.91      |
|     -      | Change%  |  0.77  |   -11.1    |  -2.09  |   1.64  | 1.64473684211  |
+------------+----------+--------+------------+---------+---------+----------------+


    

      

      

        
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -36,12 +36,56 @@
 #include <asm/reg.h>
 #include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
 #include <asm/opal.h>
+#include <linux/timer.h>
 
 #define POWERNV_MAX_PSTATES	256
 #define PMSR_PSAFE_ENABLE	(1UL << 30)
 #define PMSR_SPR_EM_DISABLE	(1UL << 31)
 #define PMSR_MAX(x)		((x >> 32) & 0xFF)
 
+#define MAX_RAMP_DOWN_TIME				5120
+/*
+ * On an idle system we want the global pstate to ramp-down from max value to
+ * min over a span of ~5 secs. Also we want it to initially ramp-down slowly and
+ * then ramp-down rapidly later on.


      

      
Where does 5 seconds come from?

Why 5 and not 10, or not 2? Is there some time period inherit in
hardware or software that this is computed from?

    

    
 As global pstates are per-chip and there are max 12 cores, so if the system is really
 idle, considering 5 seconds for each cores, it should take 60 seconds for the chip to
 go to pmin.

    

      

        
+/* Interval after which the timer is queued to bring down global pstate */
+#define GPSTATE_TIMER_INTERVAL				2000


      

      
in ms?

    

    
Yes its 2000 ms.


    

      

    

    

      

    

    

  


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