In r255760, I optimized the SectionMemoryManager to make better use
of virtual memory on platforms where the allocation granularity was
bigger than the protection granularity. As part of this, fixing up
the free list became more complicated and was moved into
`applyMemoryGroupPermissions`. Unfortunately, I forgot to actually
remove the call that drops the free list for RO memory (I did
remove the corresponding one for RX memory), defeating the whole
optimization.
llvm-svn: 257293
Summary: On Windows, the allocation granularity can be significantly
larger than a page (64K), so with many small objects, just clearing
the FreeMem list rapidly leaks quite a bit of virtual memory space
(if not rss). Fix that by only removing those parts of the FreeMem
blocks that overlap pages for which we are applying memory permissions,
rather than dropping the FreeMem blocks entirely.
Reviewers: lhames
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D15202
llvm-svn: 255760
Summary:
Without this patch, the memory manager would call `mprotect` on every memory
region it ever allocated whenever it wanted to finalize memory (i.e. not just
the ones it just allocated). This caused terrible performance problems for
long running memory managers. In one particular compile heavy julia benchmark,
we were spending 50% of time in `mprotect` if running under MCJIT.
Fix this by splitting allocated memory blocks into those on which memory
permissions have been set and those on which they haven't and only running
`mprotect` on the latter.
Reviewers: lhames
Subscribers: reames, llvm-commits
Differential Revision: http://reviews.llvm.org/D13156
llvm-svn: 248981
David Majnemer