| commit | 77f9b2728eb08456899e6500328e00ec4829dddf | [log] [tgz] |
|---|---|---|
| author | Tobias Klauser <tklauser@distanz.ch> | Fri Sep 14 09:57:06 2018 +0200 |
| committer | Tobias Klauser <tobias.klauser@gmail.com> | Tue Sep 18 15:41:44 2018 +0000 |
| tree | 495c35ea089d82b301de96d575a699b3cf7f6db4 | |
| parent | a0f5d5f8830e578892c47f7704e6a2616273aac1 [diff] |
runtime: use MADV_FREE on Linux if available On Linux, sysUnused currently uses madvise(MADV_DONTNEED) to signal the kernel that a range of allocated memory contains unneeded data. After a successful call, the range (but not the data it contained before the call to madvise) is still available but the first access to that range will unconditionally incur a page fault (needed to 0-fill the range). A faster alternative is MADV_FREE, available since Linux 4.5. The mechanism is very similar, but the page fault will only be incurred if the kernel, between the call to madvise and the first access, decides to reuse that memory for something else. In sysUnused, test whether MADV_FREE is supported and fall back to MADV_DONTNEED in case it isn't. This requires making the return value of the madvise syscall available to the caller, so change runtime.madvise to return it. Fixes #23687 Change-Id: I962c3429000dd9f4a00846461ad128b71201bb04 Reviewed-on: https://go-review.googlesource.com/135395 Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
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