40 lines
1.4 KiB
Diff
40 lines
1.4 KiB
Diff
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Description: rts: Ensure we always give MADV_DONTNEED a chance in osDecommitMemory
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Author: Ben Gamari <bgamari.foss@gmail.com>
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Origin: upstream, https://phabricator.haskell.org/D2780
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Bug: https://ghc.haskell.org/trac/ghc/ticket/12865
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Bug-Debian: https://bugs.debian.org/847677
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---
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This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
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Index: ghc-8.0.2/rts/posix/OSMem.c
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===================================================================
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--- ghc-8.0.2.orig/rts/posix/OSMem.c
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+++ ghc-8.0.2/rts/posix/OSMem.c
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@@ -522,11 +522,24 @@
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#ifdef MADV_FREE
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// Try MADV_FREE first, FreeBSD has both and MADV_DONTNEED
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- // just swaps memory out
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+ // just swaps memory out. Linux >= 4.5 has both DONTNEED and FREE; either
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+ // will work as they both allow the system to free anonymous pages.
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+ // It is important that we try both methods as the kernel which we were
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+ // built on may differ from the kernel we are now running on.
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r = madvise(at, size, MADV_FREE);
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-#else
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- r = madvise(at, size, MADV_DONTNEED);
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+ if(r < 0) {
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+ if (errno == EINVAL) {
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+ // Perhaps the system doesn't support MADV_FREE; fall-through and
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+ // try MADV_DONTNEED.
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+ } else {
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+ sysErrorBelch("unable to decommit memory");
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+ }
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+ } else {
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+ return;
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+ }
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#endif
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+
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+ r = madvise(at, size, MADV_DONTNEED);
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if(r < 0)
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sysErrorBelch("unable to decommit memory");
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}
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