| Title | Write barrier may be harmful to performance |
| Status | open |
| Priority | optional |
| Assigned user | Gareth Rees |
| Organization | Ravenbrook |
| Description | The write barrier has positive and negative impacts on performamce. Positive: it allows the MPS to maintain a remembered set for a segment and so avoid scanning it. Negative: it incurs a barrier hit every time there is a write. The MPS has been written under the assumption that the positive outweighs the negative. But for segments with frequent writes this may be a false assumption: it might be better to drop the write barrier and pay the cost of always scanning it. |
| Analysis | The MPS could spot the bad cases, and drop the write barrier. See changes [1] and [2]. |
| How found | customer |
| Evidence | [1] <https://info.ravenbrook.com/infosys/cgi/perfbrowse.cgi?%40describe+186975>[2] < https://info.ravenbrook.com/infosys/cgi/perfbrowse.cgi?%40describe+186988> |
| Created by | Gareth Rees |
| Created on | 2015-08-05 14:00:58 |
| Last modified by | Gareth Rees |
| Last modified on | 2015-08-05 14:00:58 |
| History | 2015-08-05 GDR Created. |