| Title | MVFF is slow in the hot variety |
| Status | closed |
| Priority | optional |
| Assigned user | Gareth Rees |
| Organization | Ravenbrook |
| Description | Travis build 1503.2 [1] says: Performance ratio (hot/rash) for mvff: 148% This is not acceptable: it indicates that MVFF is spending a third of its time checking assertions. |
| Analysis | Profiling the HOT build with Instruments shows: 6.7% LandCheck (< LandSize, LandFlush, LandInsert, LandIterateAndDelete) 5.0% PoolCheck (< PoolHasRange, PoolFree, PageAlloc, TractInit, MVFFFree, mps_free, PoolAlloc) 4.6% cbsUpdateFastNode 4.6% SplaySplitRev 3.6% PoolOfRange 3.3% cbsCompare 2.8% PoolFree 2.6% LandSize |
| How found | automated_test |
| Evidence | [1] https://travis-ci.org/Ravenbrook/mps/jobs/124506877 |
| Created by | Gareth Rees |
| Created on | 2016-04-20 16:52:53 |
| Last modified by | Gareth Rees |
| Last modified on | 2016-09-04 19:20:23 |
| History | 2016-04-20 GDR Created. |
| Change | Effect | Date | User | Description |
|---|---|---|---|---|
| 192148 | closed | 2016-09-04 19:20:05 | Gareth Rees | Add _CRITICAL to assertions on the critical path for manual-allocation-bound programs using MVFF. This brings the hot/rash ratio for "djbench mvff" down from over 150% to about 130%. |