7 ms·
I did my own testing a while back, because I wanted to measure if these actually make a performance impact for my use case. Net result: they do not. For my use
by jwr 7y ago
I did my own testing a while back, because I wanted to measure if these actually make a performance impact for my use case.
Net result: they do not. For my use case (Clojure/JVM and ClojureScript compilation), compile times did not get shorter. There seemed to be a slight improvement, but it was below the level of measuring noise (which was around 8%).
My conclusion was that while the system might indeed be faster by several percent, it is not measurable in my case, so I should not even bother, given the possible risks.
- coldpie 7y agoNice work. Anyone claiming performance improvements without an accompanying benchmark that is relevant to your usecase is wasting your time.
- irthomasthomas 7y agoMy experience was different. My laptop boots in half the time with these mitigations disabled, and is noticeably much faster to use.
- asdfasgasdgasdg 7y agoThat's weird. I don't think anyone has measured these mitigations at a 50% perf hit even on crafted workloads. I wonder if something else is going on.
- lallysingh 7y ago15% of pure cpu, but that doesn't take the consequences of the CPU improvement in other systems (e.g. crypto fs leading to higher iop rates, etc).
- ogre_codes 7y agoRunning insecure performance enhancing kernel mods to speed up crypto fs.... It's a self defeating performance tip!
- lallysingh 7y agoTBH there's different threat models there. A crypto fs makes sense if you're worried about a box getting stolen, while spectre/etc aren't a concern if you're running regular userland stuff on a single-user box.
- walki 7y ago> Net result: they do not. For my use case (Clojure/JVM and ClojureScript compilation), compile times did not get shorter. There seemed to be a slight improvement, but it was below the level of measuring noise (which was around 8%). I think the level of measuring noise is 0.5%, at least that is what low level system programmers generally consider as noise...
- abainbridge 7y agoI don't think anyone else gets to say how much noise the GP saw in their test.
- betimsl 7y agoHow can you know that information?
- jwr 7y agoCompile times for my project are around 2m15s to 2m30s. Since this work involves lots of CPU (some single-threaded, some multi-threaded work) and I/O, the spread mentioned above is what I get with multiple measurements. While it's true that without the mitigations times were much closer to the 2:15 mark, there were still outliers at 2:24. Which means it's hard to draw any meaningful conclusions. Not sure where you got the "0.5%" figure from.
- alinspired 7y agosame conclusion on the hardware i tested with