Re: [PATCH] Implement timekeeping for rumprun/hw (x86)

  • From: Antti Kantee <pooka@xxxxxx>
  • To: rumpkernel-users@xxxxxxxxxxxxx
  • Date: Sat, 04 Jul 2015 16:06:22 +0000

On 04/07/15 15:47, Martin Lucina wrote:

Interesting. Perhaps your QEMU is showing even more overhead for PIT
interrupt delivery than mine?

So you can't repeat the problem? Interesting.

pooka@watou:~$ qemu-system-x86_64 --version
QEMU emulator version 2.1.0 (Debian 2.1+dfsg-4ubuntu6.7), Copyright (c) 2003-2008 Fabrice Bellard

Can you run the test program below with, say, '10 500', '10 1000' and '10
5000' as parameters and report the output? Also, if possible, run it in
both POSIX mode and BMK mode (built with -DBMK, you'll need to comment out
the "die" if the stub link fails in -gcc).

Not sure if evident from the data: that program also runs slow over the wall clock in both modes. (not sure if expected or not)

POSIX mode:

10 loops of 500000000 ns
2015-07-04 15:52:34 1.540007999
>> delta 520000000 overhead 20000000
2015-07-04 15:52:34 2.60007999
>> delta 520000000 overhead 20000000
2015-07-04 15:52:35 2.580007999
>> delta 520000000 overhead 20000000
2015-07-04 15:52:35 3.90007999
>> delta 510000000 overhead 10000000
2015-07-04 15:52:36 3.640007999
>> delta 550000000 overhead 50000000
2015-07-04 15:52:36 4.160007999
>> delta 520000000 overhead 20000000
2015-07-04 15:52:37 4.670007999
>> delta 510000000 overhead 10000000
2015-07-04 15:52:38 5.220007999
>> delta 550000000 overhead 50000000
2015-07-04 15:52:38 5.760007999
>> delta 540000000 overhead 40000000
2015-07-04 15:52:39 6.270007999
>> delta 510000000 overhead 10000000
total overhead 250000000


10 loops of 1000000000 ns
2015-07-04 15:54:27 2.20007999
>> delta 1000000000 overhead 0
2015-07-04 15:54:28 3.60007999
>> delta 1040000000 overhead 40000000
2015-07-04 15:54:29 4.80007999
>> delta 1020000000 overhead 20000000
2015-07-04 15:54:30 5.110007999
>> delta 1030000000 overhead 30000000
2015-07-04 15:54:31 6.130007999
>> delta 1020000000 overhead 20000000
2015-07-04 15:54:32 7.130007999
>> delta 1000000000 overhead 0
2015-07-04 15:54:33 8.170007999
>> delta 1040000000 overhead 40000000
2015-07-04 15:54:34 9.190007999
>> delta 1020000000 overhead 20000000
2015-07-04 15:54:36 10.230007999
>> delta 1040000000 overhead 40000000
2015-07-04 15:54:37 11.240007999
>> delta 1010000000 overhead 10000000
total overhead 220000000

10 loops of 5000000000 ns
2015-07-04 15:55:16 6.40007999
>> delta 5020000000 overhead 20000000
2015-07-04 15:55:21 11.60007999
>> delta 5020000000 overhead 20000000
2015-07-04 15:55:26 16.70007999
>> delta 5010000000 overhead 10000000
2015-07-04 15:55:31 21.80007999
>> delta 5010000000 overhead 10000000
2015-07-04 15:55:36 26.110007999
>> delta 5030000000 overhead 30000000
2015-07-04 15:55:41 31.140007999
>> delta 5030000000 overhead 30000000
2015-07-04 15:55:46 36.150007999
>> delta 5010000000 overhead 10000000
2015-07-04 15:55:51 41.180007999
>> delta 5030000000 overhead 30000000
2015-07-04 15:55:57 46.220007999
>> delta 5040000000 overhead 40000000
2015-07-04 15:56:02 51.260007999
>> delta 5040000000 overhead 40000000
total overhead 240000000


BMK mode:


10 loops of 500000000 ns
2015-07-04 16:00:15 1.554259545
>> delta 511127707 overhead 11127707
2015-07-04 16:00:15 2.110248320
>> delta 551605470 overhead 51605470
2015-07-04 16:00:16 2.622365662
>> delta 511208464 overhead 11208464
2015-07-04 16:00:16 3.172868378
>> delta 549621998 overhead 49621998
2015-07-04 16:00:17 3.699099076
>> delta 523255782 overhead 23255782
2015-07-04 16:00:17 4.245581776
>> delta 545600837 overhead 45600837
2015-07-04 16:00:18 4.787663988
>> delta 541209332 overhead 41209332
2015-07-04 16:00:19 5.295928350
>> delta 507168470 overhead 7168470
2015-07-04 16:00:19 5.827403204
>> delta 530607087 overhead 30607087
2015-07-04 16:00:20 6.349954316
>> delta 521692235 overhead 21692235
total overhead 293097382

10 loops of 1000000000 ns
2015-07-04 16:00:41 2.76118858
>> delta 1025234468 overhead 25234468
2015-07-04 16:00:42 3.118423524
>> delta 1037960329 overhead 37960329
2015-07-04 16:00:43 4.142613300
>> delta 1023277656 overhead 23277656
2015-07-04 16:00:44 5.190943621
>> delta 1047451253 overhead 47451253
2015-07-04 16:00:45 6.206561460
>> delta 1014737858 overhead 14737858
2015-07-04 16:00:46 7.207432914
>> delta 1000006058 overhead 6058
2015-07-04 16:00:47 8.209894283
>> delta 1000071632 overhead 71632
2015-07-04 16:00:48 9.212718783
>> delta 1000004237 overhead 4237
2015-07-04 16:00:49 10.224447143
>> delta 1010870722 overhead 10870722
2015-07-04 16:00:50 11.250859548
>> delta 1025524342 overhead 25524342
total overhead 185138555


10 loops of 5000000000 ns
2015-07-04 16:01:19 6.58619968
>> delta 5012382694 overhead 12382694
2015-07-04 16:01:24 11.75341605
>> delta 5002332620 overhead 2332620
2015-07-04 16:01:29 16.95407992
>> delta 5016408968 overhead 16408968
2015-07-04 16:01:34 21.96314368
>> delta 5000003565 overhead 3565
2015-07-04 16:01:39 26.136353515
>> delta 5039159627 overhead 39159627
2015-07-04 16:01:44 31.169847300
>> delta 5032569191 overhead 32569191
2015-07-04 16:01:49 36.206355899
>> delta 5035602956 overhead 35602956
2015-07-04 16:01:54 41.208339853
>> delta 5001046593 overhead 1046593
2015-07-04 16:01:59 46.209260844
>> delta 5000003317 overhead 3317
2015-07-04 16:02:04 51.225259892
>> delta 5015111055 overhead 15111055
total overhead 154620586

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