| Title | mpsicv test failure |
| Status | closed |
| Priority | essential |
| Assigned user | Gareth Rees |
| Organization | Ravenbrook |
| Description | The mpsicv test case fails in the COOL variety. Here's it failing on Ubuntu (lii6gc): $ code/lii6gc/cool/mpsicv 237086722 [...] Collection 49, 172378 objects. commit_limit_set before: 1 And here's a failure on OS X (xci6ll): $ code/xc/Debug/mpsicv 2010345829 Collection 49, 172094 objects. commit_limit_set before: 1 |
| Analysis | Result code 1 is RES_FAIL; ArenaSetCommitLimit returns this if limit < arena->committed - arena->spareCommitted Running this under GDB: (gdb) b arena.c:660 Breakpoint 1 at 0x100007ab8: file arena.c, line 660. (gdb) run 2010345829 [...] Breakpoint 1, ArenaSetCommitLimit (arena=0x100178000, limit=20901888) at arena.c:660 660 res = ResFAIL; (gdb) p limit $1 = 20901888 (gdb) p arena->committed $2 = 20905984 (gdb) p arena->spareCommitted $3 = 0 The test is trying to provoke an MPS_RES_COMMIT_LIMIT error from mps_alloc by setting the commit limit. But it does so in the following way: committed = mps_arena_committed(arena); reserved = mps_arena_reserved(arena); cdie(reserved >= committed, "reserved < committed"); die(mps_pool_create(&pool, arena, mps_class_mv(), (size_t)0x1000, (size_t)1024, (size_t)16384), "commit pool create"); limit = mps_arena_commit_limit(arena); die(mps_arena_commit_limit_set(arena, committed), "commit_limit_set before"); The test case expects the arena not to commit any more memory between the call to mps_arena_committed and the call to mps_arena_commit_limit_set -- but in between is a call to mps_pool_create which might well cause more virtual memory to be committed. Clearly this is an error in the test case, not the MPS: the commit limit should be taken *after* creating the pool. |
| How found | automated_test |
| Evidence | None. |
| Observed in | 1.110.0 |
| Created by | Gareth Rees |
| Created on | 2013-03-07 13:09:35 |
| Last modified by | Gareth Rees |
| Last modified on | 2013-03-07 16:45:48 |
| History | 2013-03-07 GDR Created. |
| Change | Effect | Date | User | Description |
|---|---|---|---|---|
| 181080 | closed | 2013-03-07 16:45:48 | Gareth Rees | Fix to the mpsicv test case: get the arena's committed memory after creating the pool, so that the creation of the pool can't cause the committed memory to be bumped upwards. |