987297 - Improve memory usage of profiler by packing ProfileEntry structs together better

Status: RESOLVED FIXED

(Core :: Gecko Profiler, defect)

Description

[Viktor Stanchev [:vikstrous]]

As mentioned in bug 962262, we can reduce profiler memory usage significantly (37% on 32 bit and 44% on 64 bit) by not wasting space in the circular buffer of of ProfileEntry structs.

Comment 1

[Viktor Stanchev [:vikstrous]]

We have 2 ideas to pack the structs better.

1. Use #pragma pack and let the compiler deal with unaligned access

2. Group the structs in groups of 8 so that we combine the char tag names into one 8 byte blob followed by 8 data blobs of 4 or 8 bytes (depending on platform).

Option 1 is *much* simpler to implement.

Comment 2

[Benoit Girard (:BenWa)]

Jeff suggest:
3. We can make the ring buffer a binary buffer and do a manual memcpy in and out and have that work in bytes. It's not that hard to implement and it should only require modification to the circular buffer code (read, write) and nothing else outside.

This may be the best way to go rather then fight with #pragma features that may cause a lot of headaches.

Comment 3

[Viktor Stanchev [:vikstrous]]

Attachment: memory_pack

https://tbpl.mozilla.org/?tree=Try&rev=64dc7862407f

I also tested on B2G on a hamachi and the tags were 9 bytes.

Comment 4

[Viktor Stanchev [:vikstrous]]

Attachment: profiler_memory_pack

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/0219a7db2289

Comment 6

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/0219a7db2289

Comment 7

[Firefox Commit Bot]

The following changeset is now in Firefox Nightly:

> 0219a7db2289 Bug 987297 - Improve memory usage of profiler by packing ProfileEntry structs together better. r=bgirard

Nightly Build Information:

        ID: 20140402030201
 Changeset: 4941a2ac0786109b08856738019b016a6c5a66a6
   Version: 31.0a1
      TBPL: https://tbpl.mozilla.org/?rev=4941a2ac0786
       URL: https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/04/2014-04-02-03-02-01-mozilla-central

Download Links:

>         Linux x86: https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/04/2014-04-02-03-02-01-mozilla-central/firefox-31.0a1.en-US.linux-i686.tar.bz2
>      Linux x86_64: https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/04/2014-04-02-03-02-01-mozilla-central/firefox-31.0a1.en-US.linux-x86_64.tar.bz2
> Linux x86_64 ASAN: https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/04/2014-04-02-03-02-01-mozilla-central/firefox-31.0a1.en-US.linux-x86_64-asan.tar.bz2
>               Mac: https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/04/2014-04-02-03-02-01-mozilla-central/firefox-31.0a1.en-US.mac.dmg
>             Win32: https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/04/2014-04-02-03-02-01-mozilla-central/firefox-31.0a1.en-US.win32.installer.exe
>             Win64: https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/04/2014-04-02-03-02-01-mozilla-central/firefox-31.0a1.en-US.win64-x86_64.installer.exe

Previous Nightly Build Information:

        ID: 20140401030203
 Changeset: 1417d180a1d8665b1a91b897d1cc4cc31e7980d4
   Version: 31.0a1
      TBPL: https://tbpl.mozilla.org/?rev=1417d180a1d8
       URL: https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/04/2014-04-01-03-02-03-mozilla-central