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Thread: 24.04 considerably slower than 20.04

  1. #1
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    24.04 considerably slower than 20.04

    My main test server is still 20.04, as I skipped 22.04 on real hardware. Doing some testing for the irqbalance thread necessitated 24.04 on real hardware, verses a VM, so I added 24.04 server to my main test server as dual boot. I noticed the test ran a lot slower. Here is some data.

    The kernel is: 6.7.0-060700-generic #202401072033 SMP PREEMPT_DYNAMIC Sun Jan 7 20:43:59 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux.
    The test is 6 pairs of token passing rings, doing pretty much no work before passing the token along. The purpose of this test is to have the system prefer to use shallow idle states and to be a challenge for the teo (Timer Events Orientated) idle governor because it is not a time based test. I.E. the menu idle governor should do better for this test. The irqbalance service is disabled for this work (which I why I am starting a new thread for this). Results (30M loops):

    Code:
     OS   : idle gov: uSec/loop: %      : R time    : U time    : S time      : 
    20.04 : menu    : 4.66     :        :  2:20.150 :  1:09.556 :  11:36.771
    24.04 : menu    : 5.24     : +12.44 :  2:36.818 :  0:12.027 :   2:20.262
          :         :          :        :           :           :
    20.04 : teo     : 5.15     :        :  2:34.527 :  0:42.682 :   6:0.137
    24.04 : teo     : 6.02     : +16.89 :  3:0.884  :  1:02.892 :  10:55.273
    Note that I think there is some time sample aliasing going on the User and System times. Only the Real time is useful, in my opinion.
    There is no throttling involved. Processor package power is in the high 90's to low 100's watts area. The CPU frequency is maxed out at 4.8 GHz. The CPU frequency scaling driver is intel_pstate and the governor is powersave. HWP (HardWare Pstate control (also known as Intel Speed Shift)) was enabled (I might try HWP disabled later, along with some other tests. I'll edit this post with new data/findings.)
    Last edited by Doug S; January 9th, 2024 at 06:55 PM.
    Any follow-up information on your issue would be appreciated. Please have the courtesy to report back.

  2. #2
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    Re: 24.04 considerably slower than 20.04

    I am very curious to see how this turns out... Watching with anticipation.

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  3. #3
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    Re: 24.04 considerably slower than 20.04

    For unknown reasons, I can not edt and this to my original post. I get the dreaded, and so very frustrating "forbidden" message.

    The above was a "FAST" test. Adding "MEDIUM" and "SLOW" data (there is no use including R,U,S times):

    Code:
    MEDIUM:
     OS   : idle gov: uSec/loop: %      :
    20.04 : menu    : 12.79    :        :
    24.04 : menu    : 13.56    : +6.02  :
          :         :          :        :
    20.04 : teo     : 13.31    :        :
    24.04 : teo     : 14.11    : +6.01  :
    
    SLOW:
     OS   : idle gov: uSec/loop: %      :
    20.04 : menu    : 3055.01  :        :
    24.04 : menu    : 3131.58  : +2.51  :
          :         :          :        :
    20.04 : teo     : 2718.25  :        :
    24.04 : teo     : 3022.99  : +11.21 :
    I do not understand what is different between the two tests using the exact same kernel.
    Any follow-up information on your issue would be appreciated. Please have the courtesy to report back.

  4. #4
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    Re: 24.04 considerably slower than 20.04

    Adding HWP disabled results:

    Code:
    no-hwp:				
    OS	Gov	test	t(secs)	%
    24.04	teo	fast	179.25	16.18%
    20.04	teo	fast	154.29	
    24.04	teo	medium	178.6	4.19%
    20.04	teo	medium	171.41	
    24.04	teo	slow	192.11	-0.11%
    20.04	teo	slow	192.32	
    				
    24.04	menu	fast	158.03	12.80%
    20.04	menu	fast	140.1	
    24.04	menu	medium	173.99	3.84%
    20.04	menu	medium	167.55	
    24.04	menu	slow	195.07	-0.36%
    20.04	menu	slow	195.78
    The difference between 20.04 and 24.04 is system time, I just can not figure out why.
    Any follow-up information on your issue would be appreciated. Please have the courtesy to report back.

  5. #5
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    Re: 24.04 considerably slower than 20.04

    The Intel adrestia test is for wakeup latency information. I like it just as a good way to dwell on certain preferred idle states, depending on the test options.
    This test was done with: HWP disabled; performance CPU frequency scaling governor; kernel 6.7 generic (250 Hertz).
    Threads: 500.
    Loops: 2e6
    arrival time: 20 uSec (but it is implemented by a sleep call, so the overhead will result in longer.)
    service time: 2000 uSec (but is actually not implemented in the code as far as I can tell.)

    TEO idle governor:
    Code:
    OS and ?		uSec				uSec	
    20-teo	ave	2456		90th	percentile:	2536	
    24-teo-nosnap	ave	2891	17.71%	90th	percentile:	2972	17.19%
    24-teo	ave	2949	20.07%	90th	percentile:	3046	20.11%
    MENU idle governor:
    Code:
    OS and ?		uSec				uSec	
    20-menu	ave	2360		90th	percentile:	2474	
    24-menu-nosnap	ave	2847	20.64%	90th	percentile:	2954	19.40%
    24-menu	ave	2866	21.44%	90th	percentile:	2968	19.97%
    Aside from my inability to format the data properly, notice about 20% degradation between 20.04 and 24.04.
    When I compared running services between 20.04 and 24.04, I saw snapd, hence with it disabled for another 24.04 test.

    And for processor energy:

    MENU:
    20.04 66,539.94 Joules
    24.04 72,032.04 Joules (snapd disabled) +8%
    24.04 72,908.09 Joules +10%

    TEO:
    20.04 65,692.04 Joules
    24.04 71,571.98 Joules (snapd disabled) +9%
    24.04 72,504.09 Joules +10%
    Last edited by Doug S; January 15th, 2024 at 12:23 AM.
    Any follow-up information on your issue would be appreciated. Please have the courtesy to report back.

  6. #6
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    Re: 24.04 considerably slower than 20.04

    I don't understand why it is taking more power and running slower... Hmmm. (???)

    You said that was using the same kernel for all the tests?

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  7. #7
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    Re: 24.04 considerably slower than 20.04

    Quote Originally Posted by MAFoElffen View Post
    I don't understand why it is taking more power and running slower... Hmmm. (???)

    You said that was using the same kernel for all the tests?
    Yes, the exact same kernel.

    An idle check (20 minutes each) shows idle power consumption is the same (~1.4 watts), and idle states selections are similar between 20.04 and 24.04.

    EDIT: Previous claims of idle differences were due to operator error.
    Last edited by Doug S; January 15th, 2024 at 11:24 PM.
    Any follow-up information on your issue would be appreciated. Please have the courtesy to report back.

  8. #8
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    Re: 24.04 considerably slower than 20.04

    You might be seeing the same performance drop Linus has been seeing:-
    https://www.phoronix.com/news/Torval...Regression-Fix


    Never mind, that was on 6.8, not 6.7.
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  9. #9
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    Re: 24.04 considerably slower than 20.04

    Just to be clear, are you using the same kernel on both Ubuntu 20.04 LTS as 24.04 LTS ?

    However, the kernel 6.7.0-060700-generic is not the Ubuntu kernel so I think a comparison of the actual Ubuntu kernel would be more interesting to Ubuntu developers.

  10. #10
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    Re: 24.04 considerably slower than 20.04

    Quote Originally Posted by jbicha View Post
    Just to be clear, are you using the same kernel on both Ubuntu 20.04 LTS as 24.04 LTS ?

    However, the kernel 6.7.0-060700-generic is not the Ubuntu kernel so I think a comparison of the actual Ubuntu kernel would be more interesting to Ubuntu developers.
    Yes, the same kernel on both Ubuntu 20.04 LTS and 24.04 LTS.
    And yes, I pretty much only ever use mainline kernels. Perhaps at some later date I'll try an Ubuntu kernel.

    As a sanity check I redid the andrestia test, double and triple checking that I booted the correct kernel:

    Code:
    menu 2nd test times in uSec (24.04 snapd service disabled)				
    OS	ave	%	90th	%
    20.04	2378		2518	
    24.04	2845	19.64%	2933	16.48%
    
    teo 2nd test times in uSec (24.04 snapd service disabled)				
    OS	ave	%	90th%	%
    20.04	2434		2512	
    24.04	2990	22.84%	3076	22.45%
    Any follow-up information on your issue would be appreciated. Please have the courtesy to report back.

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