Comment by im3w1l
4 years ago
There was an article about exceptions the other day that lamented that exceptions are high latency because the exceptional path will be paged out. I would assume overcommit is to blame for that too.
4 years ago
There was an article about exceptions the other day that lamented that exceptions are high latency because the exceptional path will be paged out. I would assume overcommit is to blame for that too.
That's probably a caching issue, and caching issues are a fact of life for the foreseeable future. (Could also be a disk swap issue, but probably not.)
Why would you assume that..?
Well it's Linux's whole memory philosophy really. That you ask for data storage that may or may not be memory. This ties in with overcommit, because if you promise more memory than you have then you need a contingency plan. And that means flushing caches, it means swapping data to disk and it means erasing executable code (it is file backed, so it can just be read back in).
This fuzziness of what is and isn't in memory, is why stuff that is rarely needed needs to hit disk meaning a latency spike.