code review 204053: runtime: instrument malloc + garbage collector.

runtime: instrument malloc + garbage collector.
add simple garbage collection benchmark.

[rsc, 2010-02-06 02:54:45]

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

I'd like you to review this change.

[iant, 2010-02-06 05:28:09]

LGTM

http://codereview.appspot.com/204053/diff/1015/1022
File src/pkg/runtime/linux/amd64/sys.s (right):

http://codereview.appspot.com/204053/diff/1015/1022#newcode50
src/pkg/runtime/linux/amd64/sys.s:50: SYSCALL
On x86_64 GNU/Linux it's more efficient to use the VDSO call.  Just write
something like
    LEAQ   8(SP), DI
    MOVQ   $0xffffffffff600000, AX
    CALLQ  *AX

http://codereview.appspot.com/204053/diff/1015/1023
File src/pkg/runtime/malloc.cgo (right):

http://codereview.appspot.com/204053/diff/1015/1023#newcode251
src/pkg/runtime/malloc.cgo:251: return (byte*)v;
What's the point of this cast?  The function return type is void* and v is
already void*.

[rsc, 2010-02-06 20:38:57]

> src/pkg/runtime/linux/amd64/sys.s:50: SYSCALL
> On x86_64 GNU/Linux it's more efficient to use the VDSO call.  Just
> write something like
>    LEAQ   8(SP), DI
>    MOVQ   $0xffffffffff600000, AX
>    CALLQ  *AX

I'm going to leave this for another CL, but that's very interesting.

> src/pkg/runtime/malloc.cgo:251: return (byte*)v;
> What's the point of this cast?  The function return type is void* and v
> is already void*.

Sorry, dreg from experiments - was temporarily return (byte*)v+8;

Russ

[rsc, 2010-02-06 22:46:27]

On Sat, Feb 6, 2010 at 12:38, Russ Cox <rsc@golang.org> wrote:
>> src/pkg/runtime/linux/amd64/sys.s:50: SYSCALL
>> On x86_64 GNU/Linux it's more efficient to use the VDSO call.  Just
>> write something like
>>    LEAQ   8(SP), DI
>>    MOVQ   $0xffffffffff600000, AX
>>    CALLQ  *AX
>
> I'm going to leave this for another CL, but that's very interesting.

I misunderstood: I thought this applied to all system calls
but on further investigation I see that it's just for gettimeofday.
Will do.

Russ

[rsc, 2010-02-08 22:32:26]

*** Submitted as http://code.google.com/p/go/source/detail?r=2ddbfdba7dad ***

runtime: instrument malloc + garbage collector.
add simple garbage collection benchmark.

R=iant
CC=golang-dev
http://codereview.appspot.com/204053