|Title||Performance is poor in large address space on OS X|
|Assigned user||Richard Brooksby|
|Description||This table (taken from ) shows the effect of varying the initial allocation of address space to the arena when running the test case "scheme-advanced test-leaf.scm" on platform XCI6LL:|
"Space" is the initial allocation of address space (in MiB) when calling mps_arena_create. "Time" is the total time taken by the test case in seconds (user+sys).
You'll see that performance gets steadily worse as address space increases (time taken being roughly proportional to the address space).
|Analysis||Perhaps the "striping" of address space to make the zones interacts poorly with OS X's multi-level page table? But if that were so, we would expect the time taken to grow like the log of the address space, not linearly with the address space.|
Need to check performance on other operating systems before making any changes!
I can't reproduce this behaviour with gcbench on OS X on the 2014-05-17/chunk-tree branch. With seed 10689424:
(Interesting step change behaviour there!)
|Created by||Gareth Rees|
|Created on||2012-11-16 13:02:26|
|Last modified by||Gareth Rees|
|Last modified on||2014-05-22 15:26:06|
|History||2012-11-16 GDR Created.|
|184125||closed||2014-01-25 18:00:51||Richard Brooksby||Fix broken hysteresis in tract mapping. Only purge spare pages if it’s possible to free a chunk, rather than speculatively every reclaim. See <
Imported from Git
Author: Richard Brooksby <email@example.com> 1390672851 +0000
Committer: Richard Brooksby <firstname.lastname@example.org> 1390672851 +0000