Mercurial > hg > graal-jvmci-8
comparison src/share/vm/runtime/virtualspace.cpp @ 22973:340ca8812af9
8067469: G1 ignores AlwaysPreTouch
Summary: Factor out pretouch code of the various virtual space management classes and use them everywhere including in G1.
Reviewed-by: stefank, ehelin, dholmes
| author | tschatzl |
|---|---|
| date | Thu, 18 Dec 2014 09:37:02 +0100 |
| parents | 78bbf4d43a14 |
| children | c2ce24504334 |
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| 22972:41a855ff6305 | 22973:340ca8812af9 |
|---|---|
| 628 _upper_high += upper_needs; | 628 _upper_high += upper_needs; |
| 629 } | 629 } |
| 630 } | 630 } |
| 631 | 631 |
| 632 if (pre_touch || AlwaysPreTouch) { | 632 if (pre_touch || AlwaysPreTouch) { |
| 633 int vm_ps = os::vm_page_size(); | 633 os::pretouch_memory(previous_high, unaligned_new_high); |
| 634 for (char* curr = previous_high; | |
| 635 curr < unaligned_new_high; | |
| 636 curr += vm_ps) { | |
| 637 // Note the use of a write here; originally we tried just a read, but | |
| 638 // since the value read was unused, the optimizer removed the read. | |
| 639 // If we ever have a concurrent touchahead thread, we'll want to use | |
| 640 // a read, to avoid the potential of overwriting data (if a mutator | |
| 641 // thread beats the touchahead thread to a page). There are various | |
| 642 // ways of making sure this read is not optimized away: for example, | |
| 643 // generating the code for a read procedure at runtime. | |
| 644 *curr = 0; | |
| 645 } | |
| 646 } | 634 } |
| 647 | 635 |
| 648 _high += bytes; | 636 _high += bytes; |
| 649 return true; | 637 return true; |
| 650 } | 638 } |