Spinlock and memory usage

[Peter Marais]

I am running mc serviceguard on a rx5600 itanium (HP-UX 11.23)with Oracle 9i. I found the system memory allocation abnormally high, 1.5Gb. Using kmeminfo I discovered that 800mb is taken up by spinlocks. Is this normal and how can I get more information as to what exactly is taking up this memory.

[Dave Olker]

Hi Peter,

This does sound a bit high for spinlock memory usage. I checked my rx5670 running 11.23 and found it was consuming several hundred megabytes of memory for the spinlock arena as well. My system is a heavily used crash & burn NFS server, so it processes a good deal of networking traffic.

I did some looking around and found a possible match in the latest LAN common patch for 11.23 - PHNE_30773. The defect in question is JAGaf18149:


( SR:8606357449 CR:JAGaf18149 )
System may hang or exhibit other symptoms associated with kernel memory leak including slow system response, increased application response/execution time, and application aborts due to insufficient resources, etc.


Looking at the JAG text, it says the main symptom of this problem was:
__________________________________________

Memory is very low to to extreme usage on the spinlock arena:

Fixed arena "spinlock" owns 2035142 pages (7.8gb).
__________________________________________


So on the test system that duplicated the problem the spinlock arena was consuming 7.8gb of memory, which is obviously worse than either of our systems, but showed the networking lab there was a definite memory leak in the spinlock code.

I installed patch PHNE_30773 on my system and checked the spinlock arena immediately after booting the system and found it was ~37.9mb. Obviously this would grow over time, but that is the baseline. I then started a huge NFS job (40GB of data written across GBE) and then checked the spinlock arena again. After the 40GB of data was processed the spinlock arena was holding steady at 38.2mb.

I'd suggest installing this patch and see if it helps with your spinlock memory usage.

Regards,

Dave

[Peter Marais]

Thanks Dave will try it and let you know with next downtime frame.

[Dave Olker · Accepted solution]

Hi Peter,

Have you had a chance to test whether PHNE_30773 affects your spinlock memory usage? I don't know how often you're able to schedule downtime in your environment, but just was curious if the effects were positive, or if there is another spinlock memory leak somewhere in the code.

Regards,

Dave

[Peter Marais]

Applied patch and system memory usage down to 800mb. This solved the problem. Thanks Dave

[Peter Marais]

Apply patch as mentioned