[Bug 911520] New: MariaDB 10 causes excessive wakeups
http://bugzilla.opensuse.org/show_bug.cgi?id=911520 Bug ID: 911520 Summary: MariaDB 10 causes excessive wakeups Classification: openSUSE Product: openSUSE Distribution Version: 13.2 Hardware: Other OS: Other Status: NEW Severity: Normal Priority: P5 - None Component: Other Assignee: bnc-team-screening@forge.provo.novell.com Reporter: suse@bugs.jan.ritzerfeld.org QA Contact: qa-bugs@suse.de Found By: --- Blocker: --- Akonadi uses mysqld for its database and since openSUSE 13.2, MariaDB 10 is used for that. However, mysqld of 13.2 causes excessive 25 wakeups per second according to powertop, while actually doing nothing. "strace -f -p $(pidof mysqld)" reveals that its roundabout 50(sic!) processes are constantly reacting to timeouts for "select" or "futex resumed". -- You are receiving this mail because: You are on the CC list for the bug.
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Bernhard Wiedemann
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Weihua Du
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Per Jessen
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Christos Gourdoupis
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Jan Ritzerfeld
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--- Comment #4 from Christos Gourdoupis
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--- Comment #5 from Jan Ritzerfeld
You must be right there. However I investigated it further today in several machines I maintain, and wasn't able to spot a huge difference in wakeups between 13.1 and 13.2.
That's strange. I set up two virtualbox machines (512MB RAM, 1 CPU) with the default openSUSE 13.1 and 13.2 installations. mysqld causes 5-7 wakeups per second on 13.1 and 10-12 on 13.2. That are about 50% of the total number of wakeups in both cases (ignoring VBoxClient on 13.1). And, 13.2 increased them by 100%! However, they do not match the 25 wakeups per second I reported. Thus, I assigned them 2 CPUs and tested again. Now, mysqld causes 18-25 wakeups on 13.2 and 11-17 on 13.1. Again that are about 50% of the total number of wakeups in both cases (ignoring VBoxClient on 13.1). And, 13.2 increased them up to 60%.
They were fluctuating between 10 and 25 in both versions.
Here, they do not fluctuate that much here if you wait a few minutes without "touching" the computer. I.e., no mouse movements, no keyboard strokes...
I even installed mariadb 10 in a 13.1 machine and didn't notice any downgrade in that aspect.
That will be the next test here.
I wonder whether the increased wakeups you are observing, are due to changes in Akonadi and the rest of the apps that depend on it.
I would not exclude this possibility, but nothing else causes any significant amount of wakeups, i.e. more than 1 per second, including any akonadi related process. However, when using 13.2, my real machine and the virtualbox, both with 2 CPUs, show an huge increase in the number of wakeups for nscd and KDE konsole. Maybe it is a multi-CPU kernel "problem"? Or powertop is misreporting in case of more than 1 CPU. -- You are receiving this mail because: You are on the CC list for the bug.
http://bugzilla.opensuse.org/show_bug.cgi?id=911520
Jan Ritzerfeld
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--- Comment #6 from Jan Ritzerfeld
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--- Comment #7 from Christos Gourdoupis
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--- Comment #8 from Jan Ritzerfeld
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Christos Gourdoupis
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--- Comment #10 from Jan Ritzerfeld
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