[mythtv-users] 0.25 SQL CPU Load issues after optimisation

Mike Perkins mikep at randomtraveller.org.uk
Wed Jul 18 09:58:52 UTC 2012

On 18/07/12 06:03, Thomas Mashos wrote:
> On Tue, Jul 17, 2012 at 5:22 PM, Another Sillyname
> <anothersname at googlemail.com> wrote:
>> On 18 July 2012 00:46, Thomas Mashos <thomas at mashos.com> wrote:
>>> On Tue, Jul 17, 2012 at 4:05 PM, Another Sillyname
>>> <anothersname at googlemail.com> wrote:
>>>> On 18 July 2012 00:01, Gary Buhrmaster <gary.buhrmaster at gmail.com> wrote:
>>>>> On Tue, Jul 17, 2012 at 10:48 PM, Another Sillyname
>>>>> <anothersname at googlemail.com> wrote:
>>>>> ....
>>>>>> I am running ext4 and noticed from a previous comment on this problems
>>>>>> that ext4 barriers could be an issue but couldn't find anything
>>>>>> explanatory in the mailing list archives to explain this.
>>>>> In my experience, ext4 barriers usually manifest themselves are disk I/O
>>>>> wait, and not high CPU usage (mysql is actually waiting a lot).
>>>>> If you are using innodb tables (which is possible if you rebuilt your system
>>>>> with a newer mysql server) you should review the recommendations at:
>>>>>     http://www.mythtv.org/wiki/Tune_MySQL
>>>>> Regardless of whether they help this particular issue, they will
>>>>> help overall performance in the long run.
>>>> Thanks Gary but I'd already done that, I've been looking at this for 3
>>>> days now and as a number of people seem to have experienced this
>>>> problem without a clearly defined problem/solution I though it would
>>>> be useful to try to get some expert focus on it which means not me.
>>> Looks like Linux Mint 13 is based on Ubuntu 12.04, so you did get
>>> MySQL 5.5 from that which has innodb enabled. As previously suggested,
>>> you aren't experiencing the same issue that other people have
>>> commented on. If you were, those tuning parameters would have resolved
>>> it.
>>> Are you running the MythTV updates from the Mythbuntu repos?
>> When you say updates can you be specific possibly.
>> I installed Myth from the Mint Repos that do use the Ubuntu repos and
>> am running 0.25+Fixes 20120410.1f5962a.0ubuntu1
>> Which I assume is coming from the standard Ubuntu repos rather then a
>> specific mint repo.
> There is newer packages available at the PPA here
> https://launchpad.net/~mythbuntu/+archive/0.25
Somebody recently had mysql problems which turned out to be temp file space. 
That's a fairly gnarly looking sql statement and probably results in various 
temporary tables being created. Have you enough space in /tmp or wherever your 
my.cnf places temp stuff?


Mike Perkins

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