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https://issues.apache.org/jira/browse/TS-1405?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13631977#comment-13631977
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Leif Hedstrom commented on TS-1405:
-----------------------------------
Couple of more metrics, related to CPU usage and context switching:
Without the patch, doing a 60s run, I see
{code}
CPU USER NICE SYS IDLE Wait IRQ SIRQ
----- ------ ------ ------ ------ ------ ------ ------
cpu 445.5% 0.0% 161.5% 104.4% 0.1% 12.7% 73.6%
cpu0 0.9% 0.0% 17.6% 0.0% 0.0% 9.6% 71.6%
cpu1 61.7% 0.0% 20.1% 17.1% 0.1% 0.5% 0.3%
cpu2 63.0% 0.0% 20.5% 15.5% 0.0% 0.4% 0.3%
cpu3 64.5% 0.0% 21.3% 13.2% 0.0% 0.5% 0.3%
cpu4 67.2% 0.0% 22.4% 9.5% 0.0% 0.4% 0.3%
cpu5 65.8% 0.0% 21.4% 11.9% 0.0% 0.5% 0.3%
cpu6 62.4% 0.0% 20.5% 16.1% 0.0% 0.4% 0.3%
cpu7 60.1% 0.0% 17.9% 21.2% 0.0% 0.3% 0.3%
Context switches/sec: 13225.8
Interrupts/sec: 51887.3
{code}
With the patch, again a 60s run, I see
{code}
CPU USER NICE SYS IDLE Wait IRQ SIRQ
----- ------ ------ ------ ------ ------ ------ ------
cpu 277.8% 0.0% 135.0% 305.6% 0.2% 14.9% 60.7%
cpu0 7.0% 0.0% 22.3% 0.0% 0.0% 12.2% 58.5%
cpu1 32.8% 0.0% 14.1% 51.2% 0.1% 0.4% 0.3%
cpu2 34.2% 0.0% 14.7% 49.6% 0.0% 0.4% 0.3%
cpu3 33.1% 0.0% 14.3% 50.9% 0.0% 0.4% 0.3%
cpu4 40.2% 0.0% 17.0% 41.3% 0.0% 0.4% 0.3%
cpu5 39.3% 0.0% 16.6% 42.7% 0.0% 0.4% 0.3%
cpu6 38.9% 0.0% 16.5% 43.1% 0.0% 0.4% 0.3%
cpu7 52.4% 0.0% 19.4% 26.7% 0.0% 0.3% 0.3%
Context switches/sec: 37947.0
Interrupts/sec: 64170.1
{code}
Besides not being able to use as much of the CPU with the patch, also notice
the 3x increase in context switches. That is probably part of the problem I
think.
I am aware that my box is pinning core 0 with IRQs, I honestly don't know why
my modern linux / FC distribution isn't balancing the IRQs. But it's the same
"problem" for both runs. :)
> apply time-wheel scheduler about event system
> ----------------------------------------------
>
> Key: TS-1405
> URL: https://issues.apache.org/jira/browse/TS-1405
> Project: Traffic Server
> Issue Type: Improvement
> Components: Core
> Affects Versions: 3.2.0
> Reporter: Bin Chen
> Assignee: Bin Chen
> Fix For: 3.3.2
>
> Attachments: linux_time_wheel.patch, linux_time_wheel_v10jp.patch,
> linux_time_wheel_v11jp.patch, linux_time_wheel_v2.patch,
> linux_time_wheel_v3.patch, linux_time_wheel_v4.patch,
> linux_time_wheel_v5.patch, linux_time_wheel_v6.patch,
> linux_time_wheel_v7.patch, linux_time_wheel_v8.patch,
> linux_time_wheel_v9jp.patch
>
>
> when have more and more event in event system scheduler, it's worse. This is
> the reason why we use inactivecop to handler keepalive. the new scheduler is
> time-wheel. It's have better time complexity(O(1))
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