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Michael Anthony Knyszek 8e093e7a1c runtime: scavenge memory upon allocating from scavenged memory
Because scavenged and unscavenged spans no longer coalesce, memory that
is freed no longer has a high likelihood of being re-scavenged. As a
result, if an application is allocating at a fast rate, it may work fast
enough to undo all the scavenging work performed by the runtime's
current scavenging mechanisms. This behavior is exacerbated by the
global best-fit allocation policy the runtime uses, since scavenged
spans are just as likely to be chosen as unscavenged spans on average.

To remedy that, we treat each allocation of scavenged space as a heap
growth, and scavenge other memory to make up for the allocation.

This change makes performance of the runtime slightly worse, as now
we're scavenging more often during allocation. The regression is
particularly obvious with the garbage benchmark (3%) but most of the Go1
benchmarks are within the margin of noise. A follow-up change should
help.

Garbage: https://perf.golang.org/search?q=upload:20190131.3
Go1:     https://perf.golang.org/search?q=upload:20190131.2

Updates #14045.

Change-Id: I44a7e6586eca33b5f97b6d40418db53a8a7ae715
Reviewed-on: https://go-review.googlesource.com/c/159500
Reviewed-by: Austin Clements <austin@google.com>
2019-01-31 16:54:41 +00:00
.github .github: don't render author-facing text in ISSUE_TEMPLATE 2018-11-02 04:47:34 +00:00
api api: add os.(*File).SyscallConn to go1.12.txt 2019-01-02 21:21:53 +00:00
doc doc: note go tool tour removal in 1.12 release notes 2019-01-30 17:54:01 +00:00
lib/time lib/time: update tzdata to 2018i 2019-01-07 20:14:03 +00:00
misc cmd/cgo: don't replace newlines with semicolons in expressions 2019-01-18 03:25:40 +00:00
src runtime: scavenge memory upon allocating from scavenged memory 2019-01-31 16:54:41 +00:00
test cmd/compile: hide init functions in tracebacks 2019-01-27 04:02:46 +00:00
.gitattributes .gitattributes: prevent all magic line ending changes 2014-12-12 23:14:54 +00:00
.gitignore .gitignore: ignore src/cmd/dist/dist 2017-10-28 21:55:49 +00:00
AUTHORS A+C: change email address for Elias Naur 2019-01-23 15:05:26 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS CONTRIBUTORS: second round of updates for Go 1.12 2019-01-30 18:01:19 +00:00
favicon.ico website: recreate 16px and 32px favicon 2016-08-25 15:43:32 +00:00
LICENSE doc: revert copyright date to 2009 2016-06-01 22:40:04 +00:00
PATENTS LICENSE: separate, change PATENTS text 2010-12-06 16:31:59 -05:00
README.md README: linkify some paths 2018-06-06 18:07:01 +00:00
robots.txt godoc: serve robots.txt raw 2011-02-19 05:46:20 +11:00

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