Mercurial > hg > graal-jvmci-8
changeset 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 | 41a855ff6305 |
| children | c2ce24504334 |
| files | src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp src/share/vm/gc_implementation/shared/mutableSpace.cpp src/share/vm/runtime/os.cpp src/share/vm/runtime/os.hpp src/share/vm/runtime/virtualspace.cpp |
| diffstat | 5 files changed, 16 insertions(+), 16 deletions(-) [+] |
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--- a/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp Mon Sep 15 10:57:22 2014 +0200 +++ b/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp Thu Dec 18 09:37:02 2014 +0100 @@ -144,6 +144,9 @@ } _committed.set_range(start, end); + if (AlwaysPreTouch) { + os::pretouch_memory(page_start(start), page_start(start) + byte_size_for_pages(size_in_pages)); + } return zero_filled; }
--- a/src/share/vm/gc_implementation/shared/mutableSpace.cpp Mon Sep 15 10:57:22 2014 +0200 +++ b/src/share/vm/gc_implementation/shared/mutableSpace.cpp Thu Dec 18 09:37:02 2014 +0100 @@ -62,9 +62,7 @@ } void MutableSpace::pretouch_pages(MemRegion mr) { - for (volatile char *p = (char*)mr.start(); p < (char*)mr.end(); p += os::vm_page_size()) { - char t = *p; *p = t; - } + os::pretouch_memory((char*)mr.start(), (char*)mr.end()); } void MutableSpace::initialize(MemRegion mr,
--- a/src/share/vm/runtime/os.cpp Mon Sep 15 10:57:22 2014 +0200 +++ b/src/share/vm/runtime/os.cpp Thu Dec 18 09:37:02 2014 +0100 @@ -1513,6 +1513,11 @@ return res; } +void os::pretouch_memory(char* start, char* end) { + for (volatile char *p = start; p < end; p += os::vm_page_size()) { + *p = 0; + } +} char* os::map_memory(int fd, const char* file_name, size_t file_offset, char *addr, size_t bytes, bool read_only,
--- a/src/share/vm/runtime/os.hpp Mon Sep 15 10:57:22 2014 +0200 +++ b/src/share/vm/runtime/os.hpp Thu Dec 18 09:37:02 2014 +0100 @@ -319,6 +319,12 @@ static bool uncommit_memory(char* addr, size_t bytes); static bool release_memory(char* addr, size_t bytes); + // Touch memory pages that cover the memory range from start to end (exclusive) + // to make the OS back the memory range with actual memory. + // Current implementation may not touch the last page if unaligned addresses + // are passed. + static void pretouch_memory(char* start, char* end); + enum ProtType { MEM_PROT_NONE, MEM_PROT_READ, MEM_PROT_RW, MEM_PROT_RWX }; static bool protect_memory(char* addr, size_t bytes, ProtType prot, bool is_committed = true);
--- a/src/share/vm/runtime/virtualspace.cpp Mon Sep 15 10:57:22 2014 +0200 +++ b/src/share/vm/runtime/virtualspace.cpp Thu Dec 18 09:37:02 2014 +0100 @@ -630,19 +630,7 @@ } if (pre_touch || AlwaysPreTouch) { - int vm_ps = os::vm_page_size(); - for (char* curr = previous_high; - curr < unaligned_new_high; - curr += vm_ps) { - // Note the use of a write here; originally we tried just a read, but - // since the value read was unused, the optimizer removed the read. - // If we ever have a concurrent touchahead thread, we'll want to use - // a read, to avoid the potential of overwriting data (if a mutator - // thread beats the touchahead thread to a page). There are various - // ways of making sure this read is not optimized away: for example, - // generating the code for a read procedure at runtime. - *curr = 0; - } + os::pretouch_memory(previous_high, unaligned_new_high); } _high += bytes;