Hi Denis, Hi Cl��ment, ��Hi Frank,

On Thu, Jan 7, 2016 at 5:34 AM, Cl��ment Bera <bera.clement@gmail.com> wrote:

Hello,

Eliot, please, you told me you had the code and Denis is interested.

It uses 3 primitives for performance.

Forgive the delay.�� I thought it proper to ask permission since the code was written while I was at Qwaq. I'm attaching the code in a fairly raw state, see the attached.�� The code is MIT, but copyright 3DICC.

It is a plugin replacement for Squeak's Mutex, and with a little ingenuity could be a replacement for Squeak's Monitor.�� It is quicker because it uses three new primitives to manage entering a critical section and setting the owner, exiting the critical section and releasing the owner, and testing if a��critical��section, entering if the section is unowned.�� The use of the primitives means fewer block activations and ensure: blocks in entering and exiting the critical section, and that's the actual cause of the speed-up.

You can benchmark the code as is.�� Here are some results on 32-bit Spur, on my 2.2GHz Core i7

{Mutex new. Monitor new. CriticalSection new} collect:

[:cs| | n |

n := 0.

[cs critical: [n := n + 1]. cs critical: [n := n + 1]. cs critical: [n := n + 1]. cs critical: [n := n + 1]. cs critical: [n := n + 1].

cs critical: [n := n - 1]. cs critical: [n := n - 1]. cs critical: [n := n - 1]. cs critical: [n := n - 1]. cs critical: [n := n - 1].

n ] bench]

{Mutex new. Monitor new. CriticalSection new} collect:

[:cs| | n |

n := 0.

cs class name, ' -> ',

[cs critical: [n := n + 1]. cs critical: [n := n + 1]. cs critical: [n := n + 1]. cs critical: [n := n + 1]. cs critical: [n := n + 1].

cs critical: [n := n - 1]. cs critical: [n := n - 1]. cs critical: [n := n - 1]. cs critical: [n := n - 1]. cs critical: [n := n - 1].

n ] bench]

#( 'Mutex -> 440,000 per second. 2.27 microseconds per run.'

'Monitor -> 688,000 per second. 1.45 microseconds per run.'

'CriticalSection -> 1,110,000 per second. 900 nanoseconds per run.')

Replacement is probably trivial; rename Mutex to OldMutex, rename CriticalSection to Mutex, recompile.�� But there are lots of mutexes in the system and these are potentially owned.�� Transforming unowned ones is trivial, but transforming owned ones is, I think, impossible.�� But at least in my system there are no owned mutexes or monitors.

Frank (or anyone else), would you be interested in creating a replacement for Squeak's Monitor based on CriticalSection?

Here are the two business methods:

CriticalSection methods for mutual exclusion

critical: aBlock

"Evaluate aBlock protected by the receiver."

^self primitiveEnterCriticalSection

ifTrue: [aBlock value]

ifFalse: [aBlock ensure: [self primitiveExitCriticalSection]]

critical: aBlock ifLocked: lockedBlock

"Answer the evaluation of aBlock protected by the receiver.�� If it is already in a critical

section on behalf of some other process answer the evaluation of lockedBlock."

^self primitiveTestAndSetOwnershipOfCriticalSection

ifNil: [lockedBlock value]

ifNotNil:[:alreadyOwner|

alreadyOwner

ifTrue: [aBlock value]

ifFalse: [aBlock ensure: [self primitiveExitCriticalSection]]]

and the primitives:

CriticalSection methods for private-primitives

primitiveEnterCriticalSection

"Primitive. The receiver must be unowned or owned by the current process to proceed.

Answer if the process is owned by the current process."

<primitive: 186>

self primitiveFailed

"In the spirit of the following"

"[owner ifNil:

[owner := Processor activeProcess.

^false].

��owner = Processor activeProcess ifTrue:

[^true].

��self addLast: Processor activeProcess.

��Processor activeProcess suspend] valueUnpreemptively"

primitiveExitCriticalSection

"Primitive. Set te receiver to unowned and if any processes are waiting on

the receiver then proceed the first one, indicating that the receiver is unowned."

<primitive: 185>

self primitiveFailed

"In the spirit of the following"

"[owner := nil.

��self isEmpty ifFalse:

[process := self removeFirst.

process resume]] valueUnpreemptively"

primitiveTestAndSetOwnershipOfCriticalSection

"Primitive. Attempt to set the ownership of the receiver.

If the receiver is unowned set its owningProcess to the

activeProcess and answer false.�� If the receiver is owned

by the activeProcess answer true.�� If the receiver is owned

by some other process answer nil."

<primitive: 187>

self primitiveFail

"In the spirit of the following"

"[owner ifNil:

[owningProcess := Processor activeProcess.

^false].

��owner = Processor activeProcess ifTrue: [^true].

��^nil] valueUnpreemptively"

2016-01-07 13:24 GMT+01:00 Denis Kudriashov <dionisiydk@gmail.com>:

��

Hello.

I hear about new Monitor implementation based on new primitives.

Where to get it?

_,,,^..^,,,_

best,��Eliot