Linux has crappy instrumentation on the file cache. I tried the cachestats on perf-tools, it is producing negative numbers on cache hits on the 2x.
If the files are mmap'd, would that bypass any inotify detection when a file access occurs aka a page fault? I'm guessing yes On Wed, Dec 2, 2020 at 5:12 PM Erick Ramirez <erick.rami...@datastax.com> wrote: > From C* 2.2 onwards, SSTables get mapped to memory by mmap() so the hot > data will be accessed much faster on systems with more RAM. > > On Thu, 3 Dec 2020 at 09:57, Carl Mueller > <carl.muel...@smartthings.com.invalid> wrote: > >> I agree in theory, I just want some way to confirm that file accesses in >> the larger instance are being intercepted by the file cache, vs what is >> happening in the other case. >> >> I've tried amy tobey's pcstat >> >> I'd assume the 2x would have a file cache with lots of partial caches of >> files, churn in the files that are cached. But all the Index.db and Data.db >> files are 100% cached according to that tool >> >>>
