| commit | 1c5bd3459b2dfca44e4d313b49b525a26e38c181 | [log] [tgz] |
|---|---|---|
| author | Michael Anthony Knyszek <mknyszek@google.com> | Thu Nov 21 22:37:12 2019 +0000 |
| committer | Michael Knyszek <mknyszek@google.com> | Fri Nov 22 16:04:32 2019 +0000 |
| tree | 1c581092d959186960e1d6c4177907305c466bcd | |
| parent | 300f5d5b4bac870aa146c14cbb50dbb3902f1feb [diff] |
runtime: increase TestPhysicalMemoryUtilization threshold TestPhysicalMemoryUtilization occasionally fails on some platforms by only a small margin. The reason for this is that it assumes the scavenger will always be able to scavenge all the memory that's released by sweeping, but because of the page cache, there could be free and unscavenged memory held onto by a P which the scavenger simply cannot get to. As a result, if the page cache gets filled completely (512 KiB of free and unscavenged memory) this could skew a test which expects to scavenge roughly 8 MiB of memory. More specifically, this is 512 KiB of memory per P, and if a system is more inclined to bounce around between Ps (even if there's only one goroutine), this memory can get "stuck". Through some experimentation, I found that failures correlated highly with relatively large amounts of memory ending up in some page cache (like 60 or 64 pages) on at least one P. This change changes the test's threshold such that it accounts for the page cache, and scales up with GOMAXPROCS. Because the test constants themselves don't change, however, the test must now also bound GOMAXPROCS such that the threshold doesn't get too high (at which point the test becomes meaningless). Fixes #35580. Change-Id: I6bdb70706de991966a9d28347da830be4a19d3a1 Reviewed-on: https://go-review.googlesource.com/c/go/+/208377 Run-TryBot: Michael Knyszek <mknyszek@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
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