Re: Higher load averages running mysql on 15 instead fo 14

On 2/3/26 01:55, Pete French wrote:
> I upgraded all our machines to 15.0-STABLE last week. Which works fine, 
> but I have noticed a very curious thing where the load averages on our 
> main database machine have doubled.
> 
> See graph here...
> 
> https://api.ticketswitch.com/shared/mysql-load-average-14-to-15.png
> 
> 
> The only thing which has changed there is the operating system, and
> the re-install of the packages to match. All the versions are
> identical, config is identical, workload is identical.
> 
> The CPU usage hasn't changed, just the load averages. If I look on
> that machine, which is really only running mysql, then the processes
> in mysql are all in the state "Waiting for table metadata lock"
> 
> My hope is that FreeBSD 15 somehow calculates load averages
> differently, and I simply never noticed 100 processes
> waiting on locks before. But I also worry that maybe mysql does
> its locking using some operating system primitive, which has changed,
> and is causing this.
> 
> Any ideas anyone ?

which filesystem is your mysql data mounted on?  my fist suspect would 
be some performance change in the underlying filesystem, or how data is 
cached in memory.  systat may help shed light on this with maybe the 
vmstat, iolat or iostat options.

do you have a similar system running 14.x available for comparison purposes?

-pete

-- 
Pete Wright
[email protected]