AWS and High-CPU InstancesJuly 04, 2011 at 09:52 AM | categories: Performance, AWS, Linux | View Comments
Intel SSD 510March 02, 2011 at 07:41 AM | categories: Performance | View Comments
Intel's latest SSD pricing isn't as much of a shift as I had hoped for. As I see it, they have gone from $2.75/GB to $2.50/GB for enterprise-class SSD devices, and capacities have grown to 230-GB per device. That's an improvement, and the performance looks good. The combination of SATA-3 and lower failure rates than consumer-grade SSD may also help justify the price.
While SSD is now the logical choice over 15k-rpm disks, very few deployments use those. Instead, 10k-rpm are the workhorse for disk-heavy enterprise applications. SSD is getting closer, but still costs at least twice as much. Brand-name 10k-rpm SATA disks are available for $0.72-$1 per GB, with capacities up to 600-GB per spindle. It will take a lot of performance-related pain to cross that gap.
LWN article on impact of hugepagesFebruary 22, 2011 at 07:15 AM | categories: Performance, Linux | View Comments
Part 5 in a series by Mel Gorman describes how to measure the potential benefit from hugepages. The results match up reasonably well with CPU-intensive synthetic benchmarks on linux, which tend to show 10-15% improvement over ordinary pages.
The larger impact may be to application environments under heavy memory pressure. The OS can swap everything else out, but hugepage allocations are pinned. This is a double-edged sword. Preventing swapping may benefit some environments (cf vm.swappiness). But imagine a situation where you have 8-GB RAM and designate 4-GB for huge pages, but only use 2-GB. Now the OS has only 4-GB to manage, and the free 2-GB in huge pages are effectively wasted. If the system comes under memory pressure, that could lead to swapping or activate the OOM killer.