1987055 - Add a 'logical' page size for mozjemalloc

Status: RESOLVED FIXED

(Core :: Memory Allocator, enhancement)

Description

[Paul Bone [:pbone]]

Splitting Bug 1980056 into separate phases. This change adds the concept of a logical page size separate from physical page size, but doesn't otherwise change configuration.

Comment 1

[Paul Bone [:pbone]]

Attachment: Bug 1987055 - pt 1. Correct a comment r=glandium

Comment 2

[Paul Bone [:pbone]]

Attachment: Bug 1987055 - pt 2. Merge purge results, ReachedThreshold and Busy r=glandium

Comment 3

[Paul Bone [:pbone]]

Attachment: Bug 1987055 - pt 3. Change the dirty chunks tree to a list r=glandium

Arenas track dirty chunks in a red-black tree ordered by memory address.
Switching this to a list will make it faster to test if an item is in
the list, which is required by the next patch.

Additionally there's no reason this collection needs to be ordered or
support lookups. The ordering by memory address may have some
fragmentation benefits, the new list is operated as a FIFO. Items are
appended at the tail when they get their first dirty page, and removed
from the head as they're purged.

Comment 4

[Paul Bone [:pbone]]

Attachment: Bug 1987055 - pt 4. mChunksDirty doesn't always track all dirty chunks r=glandium

Currently a dirty chunk (that's a chunk with at least one dirty page)
must:

• Be in mChunksDirty
• Be busy pruging by another thread.

The next change will allow it so that chunks with a non-zero mNumDirty
might not be in the dirty chunks list because its impossible to purge
their pages. Therefore in this change we relax the above assumption.

Comment 5

[Paul Bone [:pbone]]

Attachment: Bug 1987055 - pt 5. Add a 'logical' page size r=glandium!,mstage!

Mozjemalloc now has a concept of logical page size for its own
structures that may be different from the system's page size.

Comment 6

[Paul Bone [:pbone]]

Attachment: Bug 1987055 - pt 6. Better purging edge cases r=glandium

Make purging smarter around edge cases. If the first or last dirty page
is not aligned with the hardware page size it will now attempt to purge
extra clean (but unused!) pages in order to capture the dirty pages.

This change also replaces some modulus operators with bitmasks.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/db8adc0130c6
https://hg.mozilla.org/integration/autoland/rev/1f042c774e7d
pt 1. Correct a comment r=glandium
https://github.com/mozilla-firefox/firefox/commit/c393a4ee5cff
https://hg.mozilla.org/integration/autoland/rev/c95f650a9e5c
pt 2. Merge purge results, ReachedThreshold and Busy r=glandium,profiler-reviewers,mstange
https://github.com/mozilla-firefox/firefox/commit/78f0dc48f99a
https://hg.mozilla.org/integration/autoland/rev/30e7989a51e7
pt 3. Change the dirty chunks tree to a list r=glandium
https://github.com/mozilla-firefox/firefox/commit/feb93ee611fb
https://hg.mozilla.org/integration/autoland/rev/50ec76065e66
pt 4. mChunksDirty doesn't always track all dirty chunks r=glandium
https://github.com/mozilla-firefox/firefox/commit/9d46a4ed0973
https://hg.mozilla.org/integration/autoland/rev/c8f4477374f3
pt 5. Add a 'logical' page size r=glandium,profiler-reviewers,mstange
https://github.com/mozilla-firefox/firefox/commit/2eace0bcf051
https://hg.mozilla.org/integration/autoland/rev/ccde073de033
pt 6. Better purging edge cases r=glandium

Comment 8

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/1f042c774e7d
https://hg.mozilla.org/mozilla-central/rev/c95f650a9e5c
https://hg.mozilla.org/mozilla-central/rev/30e7989a51e7
https://hg.mozilla.org/mozilla-central/rev/50ec76065e66
https://hg.mozilla.org/mozilla-central/rev/c8f4477374f3
https://hg.mozilla.org/mozilla-central/rev/ccde073de033