ram.png negative values ?
centminmod opened this issue · 2 comments
centminmod commented
On a idle server using data_collector.sh to grab a set sample and interval of sar memory stats seems to produce ram.png that shows negative memory usage ?
example of idle
03:18:51 AM kbmemfree kbmemused %memused kbbuffers kbcached kbcommit %commit kbactive kbinact kbdirty
03:18:52 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
03:18:53 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
03:18:54 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
03:18:55 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
03:18:56 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
03:18:57 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
03:18:58 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
03:18:59 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
03:19:00 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
03:19:01 AM 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
Average: 14085804 18822948 57.20 552972 14613692 12406532 35.44 6276896 10072964 0
chart ends up something like
I am using a forked version with a few cosmetic changes in script https://github.com/centminmod/sarviewer
- https://github.com/centminmod/sarviewer/commits/master/data_collector.sh
- https://github.com/centminmod/sarviewer/blame/master/data_collector.sh
looks like formula is off on CentOS 7 for used memory https://github.com/centminmod/sarviewer/blob/master/plotters/ram.gplot
plot '../data/ram.dat' using 1:($2/1024+$5/1024+$6/1024) title 'Free' with l ls 1, \
'' using 1:($5/1024) title 'Buffers' with l ls 2, \
'' using 1:($6/1024) title 'Cached' with l ls 3, \
'' using 1:($3/1024-$6/1024-$5/1024-$2/1024) title 'Used' with l ls 4
3rd column minus 6th minus 2nd
cat data/ram.dat
03:16:29 14082768 18825984 57.21 552952 14614432 12413540 35.46 6279684 10073504 48
03:16:31 14082768 18825984 57.21 552952 14614432 12413540 35.46 6279760 10073504 48
03:16:33 14082768 18825984 57.21 552960 14614432 12413540 35.46 6279820 10073504 84
03:16:35 14082644 18826108 57.21 552960 14614432 12413540 35.46 6279820 10073512 84
03:16:37 14082644 18826108 57.21 552960 14614432 12413540 35.46 6279820 10073512 76
03:16:39 14082644 18826108 57.21 552960 14614432 12413540 35.46 6279820 10073512 52
03:16:41 14082644 18826108 57.21 552960 14614432 12413540 35.46 6279820 10073512 52
03:16:43 14082636 18826116 57.21 552960 14614432 12413540 35.46 6279820 10073512 0
03:16:45 14082636 18826116 57.21 552960 14614432 12413540 35.46 6279820 10073512 0
03:16:47 14083220 18825532 57.21 552960 14614432 12409348 35.45 6279820 10073512 0
change plotters/ram.gplot to
plot '../data/ram.dat' using 1:($2/1024+$5/1024+$6/1024) title 'Free' with l ls 1, \
'' using 1:($5/1024) title 'Buffers' with l ls 2, \
'' using 1:($6/1024) title 'Cached' with l ls 3, \
'' using 1:($3/1024) title 'Used' with l ls 4
seems to fix it
juliojsb commented
Hi centminmod,
Thanks for checking and reporting this issue. I have been able to reproduce the error in Debian 8 Jessie and CentOS 7:
Having in mind the following data sample:
21:20:42 8038840 8324832 50.87 1780656 3139748 6558300 12.98 2710332 3843708 68
21:20:47 8050712 8312960 50.80 1780768 3139428 6546288 12.95 2697788 3842928 68
21:20:52 8051908 8311764 50.79 1780784 3139432 6518876 12.90 2698484 3842932 96
21:20:57 8052992 8310680 50.79 1780784 3139432 6518816 12.90 2697912 3842928 96
21:21:02 8051872 8311800 50.79 1780792 3139432 6518360 12.90 2699532 3842932 692
21:21:07 8034112 8329560 50.90 1780792 3139432 6504604 12.87 2718252 3842920 368
21:21:12 8034780 8328892 50.90 1780808 3139396 6526308 12.91 2716180 3842920 336
21:21:17 8047320 8316352 50.82 1780816 3139396 6520980 12.90 2703268 3842920 276
21:21:22 8048152 8315520 50.82 1780816 3139396 6534688 12.93 2703600 3842920 872
21:21:27 8050720 8312952 50.80 1780816 3139396 6522080 12.90 2699660 3842916 316
21:21:32 8049008 8314664 50.81 1780816 3139396 6522320 12.91 2700252 3842916 1168
21:21:37 8050840 8312832 50.80 1780816 3139396 6495800 12.85 2699832 3842912 40
21:21:42 8037624 8326048 50.88 1780820 3139396 6517924 12.90 2713360 3842912 40
21:21:47 8034616 8329056 50.90 1780820 3139396 6512396 12.89 2715204 3842912 40
21:21:52 8024040 8339632 50.96 1780844 3139524 6551120 12.96 2728168 3842748 392
21:21:57 7959912 8403760 51.36 1780868 3139876 6567760 12.99 2791476 3842636 1088
21:22:02 7984440 8379232 51.21 1780888 3140088 6583168 13.03 2766176 3842768 1876
21:22:07 7969552 8394120 51.30 1780920 3139608 6590244 13.04 2780864 3842932 1376
21:22:12 7970660 8393012 51.29 1781040 3139904 6593488 13.05 2782444 3843244 1308
21:22:17 7984096 8379576 51.21 1781056 3140628 6594020 13.05 2766436 3843784 1448
And that:
- Second column --> Free memory
- Third column --> Used memory
- Fifth column --> Buffers
- Sixth column --> Cached
My idea was to get the used and free memory with the following formula:
- Free memory = Free + buffers + cached
- Used memory = Used - buffers - cached
So I just changed in plotters/ram.gplot the problematic line:
'' using 1:($3/1024-$6/1024-$5/1024-$2/1024) title 'Used' with l ls 4
To this:
'' using 1:($3/1024-$5/1024-$6/1024) title 'Used' with l ls 4
Getting now the following graph:
Regards,
Julio
centminmod commented
Thanks @juliojsb 👍