R
RussellAdams
Guest
ChUIMonster If there are truly only 4 cores (out of a total of 10) and they are truly dedicated then it probably isn't a NUMA problem. Although it could still be a virtualization issue. What is the CPU entitlement? But 10 is a very strange total number to have. Usually these things come in powers of 2. 10 CPU, 256GB RAM. ChUIMonster LPAR configuration can make a big difference. The defaults for AIX are not friendly to databases. By default AIX makes everything dynamic and spreads your CPU over as many cores as it can. You have to go way out of your way to change that. Databases use large shared memory caches that must be coordinated. That is generally done with mutex locks (aka "latches") and the process of doing that requires CPU caches to be synchronized. That is *much* more efficient when the cores are dedicated and share the same silicon. Which is the exact opposite of the defaults on NUMA servers (and almost all large servers are NUMA these days) and in virtualized environments. A couple of simple commands that might shed some light: "lparstat -i" and "lssrad -va" I already posted lssrad, and it looks like one piece. The LPAR is a 4 core dedicated LPAR, we aren't using shared procs (yes, i know it's still shared under the hood). Processor folding was introduced in late AIX 5.3 to compensate for POWER's VCPU dilution problem. We have all cores folded until the first core exceeds a busy threshold, and that's set appropriately. We are seeing really very low CPU utilization (ie: 10%), and reading the spin lock documentation I take it if we were waiting in spin I would see higher CPU?
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