Hi guys...
I have a - seemingly - very big problem with our MySQL server.
There's MySQL 4.1, downloaded from MySQL.com running on it (we cant upgrade it because of severe software issues it would cause).
It's running a basic installation of Fedora 7 with SMP kernel, without graphic interface. It has 2 Quad core Xeon processors.
There's a particularly large, difficult query which takes about 15 minutes to execute on that machine. This is not the worst problem. You see, when I look at the output of SAR, I see that during the 15 minutes only One core is utilized out of the eight. See:
Code:
05:26:11 PM CPU %user %nice %system %iowait %steal %idle
05:26:12 PM all 7.43 0.00 3.59 0.00 0.00 88.99
05:26:12 PM 0 0.00 0.00 0.00 0.00 0.00 100.00
05:26:12 PM 1 0.94 0.00 0.94 0.00 0.00 98.11
05:26:12 PM 2 0.00 0.00 0.00 0.00 0.00 100.00
05:26:12 PM 3 59.41 0.00 26.73 0.00 0.00 13.86
05:26:12 PM 4 0.00 0.00 0.00 0.00 0.00 100.00
05:26:12 PM 5 0.00 0.00 0.00 0.00 0.00 100.00
05:26:12 PM 6 0.00 0.00 0.00 0.00 0.00 100.00
05:26:12 PM 7 0.00 0.00 0.00 0.00 0.00 100.00
...and even that is not on 100%. I looked at disk usage also, but no, there's only moderate HDD activity and even that is generated by some other process or so.
I've tried setting the "thread_concurrency" to 8 and 16 also, but no good. The server is at a 0.5 load, serving other requests on other processor cores rapidly when needed. But that one core is occupied with that one query and the "computing" is not distributed between cores.
Can you suggest something that would help me?
The server's exact params otherwise are the following:
Code:
HP DL380R05 CTO Chassis
HP X5355 DL380G5 FIO Kit
HP X5355 DL380G5 Kit
HP 4GB FBD PC2-5300 2x2GB Kit (x4)
HP 146GB 10K SAS 2.5 Hot Plug Hard Drive (x8, in RAID6)
HP SA Cache Battery Kit
HP NC110T PCIe Gigabit Server Adapter (x2)
HP Smart Array P400/256 DL38x LP FIO Ctr
HP RPS 350/370/380G5/385G2 Kit
Levente