4 ms·
meh, maybe they just flush TLB every time in hardware level if you disabled the mitigations, ane disabled the hardware flush if the software side can handle it
by stevefan1999 4y ago
meh, maybe they just flush TLB every time in hardware level if you disabled the mitigations, ane disabled the hardware flush if the software side can handle it
- bmacho 4y agoSo mitigations = off when they do flush, and mitigations = on when they use previous data and weird shenanigans?
- Cloudef 4y agoYeah it seems like hw migtation is slower than software
- staticassertion 4y agoThis is basically my guess. In the event of no mitigations you have to pessimistically flush TLB. In the case of mitigations the flush only has to happen in specific instances, which PCID significantly helps with but requires cooperation from both hardware and software. So maybe even something like "if PCID is not set, flush the cache" vs "if PCID changes, flush the cache". I think that would certainly account for this, and they could have improved the performance with PCID by increasing the PCID cache size.