code review 257041: runtime: clock garbage collection on bytes allocated, n...

runtime: clock garbage collection on bytes allocated, not pages in use
This keeps fragmentation from delaying
garbage collections (and causing more fragmentation).

Cuts fresh godoc (with indexes) from 261M to 166M (120M live).
Cuts toy wc program from 50M to 8M.

Fixes issue 647.

[rsc, 2010-03-06 01:41:08]

Hello r (cc: golang-dev@googlegroups.com),

I'd like you to review this change.

[r2, 2010-03-06 04:02:30]

LGTM

On Mar 5, 2010, at 5:41 PM, rsc@golang.org wrote:

> Reviewers: r,
> 
> Message:
> Hello r (cc: golang-dev@googlegroups.com),
> 
> I'd like you to review this change.
> 
> 
> Description:
> runtime: clock garbage collection on bytes allocated, not pages in use
> This keeps fragmentation from delaying
> garbage collections (and causing more fragmentation).
> 
> Cuts fresh godoc (with indexes) from 261M to 166M.
> Cuts toy wc program from 50M to 8M.
> 
> Fixes issue 647.
> 
> Please review this at http://codereview.appspot.com/257041/show
> 
> Affected files:
>  M src/pkg/runtime/extern.go
>  M src/pkg/runtime/malloc.cgo
>  M src/pkg/runtime/malloc.h
>  M src/pkg/runtime/mcache.c
>  M src/pkg/runtime/mcentral.c
>  M src/pkg/runtime/mgc0.c
>  M src/pkg/runtime/mheap.c
> 
> 

[cw, 2010-03-06 04:32:40]

Neat.

I see similar gains here on code that has objects with mixed lifetimes.  On code
where the objects are more or less created/destroyed in a linear matter the
results are the same.

[rsc, 2010-03-08 22:15:47]

*** Submitted as http://code.google.com/p/go/source/detail?r=348e71baa44e ***

runtime: clock garbage collection on bytes allocated, not pages in use
This keeps fragmentation from delaying
garbage collections (and causing more fragmentation).

Cuts fresh godoc (with indexes) from 261M to 166M (120M live).
Cuts toy wc program from 50M to 8M.

Fixes issue 647.

R=r, cw
CC=golang-dev
http://codereview.appspot.com/257041