Bug 172373 – bmalloc: scavenger runs too much on JetStream

• Component: New Bugs
• Status: RESOLVED FIXED

[Geoffrey Garen]

bmalloc: scavenger runs too much on JetStream

[Geoffrey Garen]

Created attachment 310685 [details]
Patch

[Build Bot]

Attachment 310685 [details] did not pass style-queue:


ERROR: Source/bmalloc/bmalloc/AsyncTask.h:129:  More than one command on the same line  [whitespace/newline] [4]
Total errors found: 1 in 7 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Sam Weinig]

Comment on attachment 310685 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=310685&action=review

> Source/bmalloc/ChangeLog:28
> +        One hole in this strategy is that a workload with a perfectly
> +        unfragmented heap that allocates and deallocates ~16kB every 2s will
> +        never shrink its heap. This doesn't seem to be a problem in practice.

Presumably, once it reaches critical memory pressure, it will still shrink?

[Geoffrey Garen]

> Presumably, once it reaches critical memory pressure, it will still shrink?

Yes.

[Michael Saboff]

Created attachment 311304 [details]
Updated Patch

Tested this on iOS.  Working with Geoff, we made a few changes.

[Build Bot]

Attachment 311304 [details] did not pass style-queue:


ERROR: Source/bmalloc/bmalloc/AsyncTask.h:129:  More than one command on the same line  [whitespace/newline] [4]
ERROR: Source/bmalloc/bmalloc/Heap.cpp:204:  Multi line control clauses should use braces.  [whitespace/braces] [4]
ERROR: Source/bmalloc/bmalloc/Heap.cpp:209:  Multi line control clauses should use braces.  [whitespace/braces] [4]
ERROR: Source/bmalloc/bmalloc/Heap.cpp:212:  Multi line control clauses should use braces.  [whitespace/braces] [4]
ERROR: Source/bmalloc/bmalloc/Heap.cpp:223:  Multi line control clauses should use braces.  [whitespace/braces] [4]
Total errors found: 5 in 7 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Geoffrey Garen]

Comment on attachment 311304 [details]
Updated Patch

r=me

[Michael Saboff]

Committed r217456: <http://trac.webkit.org/changeset/217456>

[Radar WebKit Bug Importer]

<rdar://problem/32479828>

[Saam Barati]

It looks like this or https://bugs.webkit.org/show_bug.cgi?id=172617 is a 1.5% slowdown on JetStream on iOS.

[Andreas Kling]

Note that if the vm.madvise_free_debug sysctl is 1, madvise(MADV_FREE_*) will synchronously zero-fill the pages. This may result in very different performance characteristics on production vs engineering builds of the OS.