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Thanks, that is interesting. They are able to pin the processes to certain cores to keep it in certain cache blocks to avoid exactly what I worry about. They

by edoo 8y ago

Thanks, that is interesting. They are able to pin the processes to certain cores to keep it in certain cache blocks to avoid exactly what I worry about. They avoid my second concern by having lots of cache memory even though they technically need a small fraction of it to maintain performance. There is a trade off, so probably still lots of room for improvement if they can get finer cache control. My fear in those scenarios is you have profiled your workload, your cluster is at 75%+ utilization, and something non standard hits and triggers a workload profile that removes any cache performance benefits, sinking your hole cluster.

BubRoss 8y ago
That would imply that accommodations for using the cache are data dependant which would be orthogonal to building in mechanics for a specifically sized cache. Also this is about CPU caches so it doesn't have anything to do with cluster utilization. A cluster will see the CPU as being ultilized at 100% regardless of how many cache misses there are.
- edoo 8y ago
  If you have a cluster at 75% utilization because the workload is fully in cache and something happens that does not allow the workload to be processed in cache and your processing speed slows by half then your cluster would immediately require twice the resources to meet the workflow demand. An attacker for example could figure out a rarely used access pattern that trashes the caches and causes a severe backup.
  - BubRoss 8y ago
    Once again, that would imply that someone is both hardcoding a cache size and yet somehow making their use of the cache data dependant. I'm not sure what specifically you are trying to say here. It sounds like you have some sort of fear of edge cases in general, regardless of anything that has to do with caches.