3 ms·
I'm not an expert, but: L3 is generally on the order of the same time as main memory - it's main purpose is to reduce the total amount of requests in order to
by jbooth 14y ago
I'm not an expert, but:
L3 is generally on the order of the same time as main memory - it's main purpose is to reduce the total amount of requests in order to conserve bandwidth
SSDs are on the order of 0.1ms, so 100,000 ns, give or take a factor of 10.
Someone smarter than me will have to answer the NUMA node question.
- MichaelGG 14y agoI think L3 is much faster; perhaps 1/3rd of main memory, assuming the line is available and not in another core. Here are some numbers for L3 cache, from Intel (probably specific to the 5500 series)[1]: L3 CACHE hit, line unshared ~40 cycles L3 CACHE hit, shared line in another core ~65 cycles L3 CACHE hit, modified in another core ~75 cycles remote L3 CACHE ~100-300 cycles Local Dram ~60 ns Remote Dram ~100 ns 60ns at 2.4GHz is ~144 cycles, right? 1: http://software.intel.com/sites/products/collateral/hpc/vtune/performance_analysis_guide.pdf http://software.intel.com/sites/products/collateral/hpc/vtun...
- CookWithMe 14y agoSorry, these were rhetorical questions :) I was trying to make the point that these numbers are somewhat arbitrary (i.e. why do I need to know the access speed to disc, when I keep everything in memory on a NUMA system?) and don't apply to all programmers (e.g. embedded systems may not have discs, L2 Caches or internet access).