4 ms·
You would think so, but as Rachel points out the Linux kernel displays some pathological behavior with noswap that even a tiny amount of swap lets it get around
by azernik 7y ago
You would think so, but as Rachel points out the Linux kernel displays some pathological behavior with noswap that even a tiny amount of swap lets it get around. Something weird is going on in the memory management code.
- VectorLock 7y agoI'm not sure what shes observing other than "feels weird" but my observation is the exact opposite, but my observations usually have some measurements to them.
- aardvarklegend 7y agoIt requires a perfect storm of just shy of 100% used memory and a lot of mmaped io. In that case the mmaped can get shunted to a handful of pages (or even one page) and so you lose all ability to have any block io larger then one page size. And every page of memory involves a fully blocking io request. It’s most certainly real for certain workloads (databases are common).
- azernik 7y ago"Feels weird" when she logs on to investigate serious performance problems that she's getting paged for.