1ebb229e8e
update to Haskell LTS version 8.x OBS-URL: https://build.opensuse.org/request/show/459907 OBS-URL: https://build.opensuse.org/package/show/devel:languages:haskell/ghc?expand=0&rev=240
60 lines
2.0 KiB
Diff
60 lines
2.0 KiB
Diff
From: Ben Gamari <bgamari.foss@gmail.com>
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Date: Thu, 1 Dec 2016 17:55:23 +0000 (-0500)
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Subject: rts: Ensure we always give MADV_DONTNEED a chance in osDecommitMemory
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X-Git-Url: https://git.haskell.org/ghc.git/commitdiff_plain/6576bf83cdf4eac05eb88a24aa934a736c91e3da
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rts: Ensure we always give MADV_DONTNEED a chance in osDecommitMemory
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As described in #12865, newer Linux kernels support both MADV_FREE and
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MADV_DONTNEED. Previously a runtime would fail to try MADV_DONTNEED if
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MADV_FREE failed (e.g. since the kernel which the image is running on
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doesn't support the latter). Now we try MADV_DONTNEED if MADV_FREE
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failed to ensure that binaries compiled on a kernel supporting MADV_FREE
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don't fail on decommit.
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Test Plan: Validate
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Reviewers: austin, erikd, simonmar
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Reviewed By: simonmar
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Subscribers: thomie
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Differential Revision: https://phabricator.haskell.org/D2780
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GHC Trac Issues: #12865
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---
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Index: ghc-8.0.1.20161117/rts/posix/OSMem.c
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===================================================================
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--- ghc-8.0.1.20161117.orig/rts/posix/OSMem.c
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+++ ghc-8.0.1.20161117/rts/posix/OSMem.c
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@@ -522,11 +522,24 @@ void osDecommitMemory(void *at, W_ size)
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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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