[Vm-dev] VM Maker: ..VMMaker.oscog-eem.618.mcz
Eliot Miranda
eliot.miranda at gmail.com
Mon Feb 17 20:22:00 UTC 2014
On Fri, Feb 14, 2014 at 8:03 AM, Levente Uzonyi <leves at elte.hu> wrote:
>
> Is it intentional that this package and the previous one are prefixed with
> dots?
oops. definitely not. i must have mistyped during the commit dialog.
fixed this. David, can you delete the
.VMMaker.oscog-eem.615
..VMMaker.oscog-eem.616
..VMMaker.oscog-eem.617
..VMMaker.oscog-eem.618
packages?
>
>
> Levente
>
>
> On Thu, 13 Feb 2014, commits at source.squeak.org wrote:
>
>
>> Eliot Miranda uploaded a new version of VMMaker to project VM Maker:
>> http://source.squeak.org/VMMaker/..VMMaker.oscog-eem.618.mcz
>>
>> ==================== Summary ====================
>>
>> Name: ..VMMaker.oscog-eem.618
>> Author: eem
>> Time: 13 February 2014, 11:51:10.104 am
>> UUID: 3756532a-fdbf-4e96-8cc9-be0f35157864
>> Ancestors: ..VMMaker.oscog-eem.617
>>
>> Some musings on Spur compaction.
>>
>> =============== Diff against ..VMMaker.oscog-eem.617 ===============
>>
>> Item was added:
>> + ----- Method: SpurMemoryManager>>abstractCompaction (in category
>> 'compaction - analysis') -----
>> + abstractCompaction
>> + "This method answers a rough estimate of compactibility."
>> + <doNotGenerate>
>> + | lowestFree freeChunks used movable |
>> + lowestFree := SmallInteger maxVal.
>> + freeChunks := Set new.
>> + used := Set new.
>> + movable := Set new.
>> + self allObjectsInFreeTreeDo:
>> + [:f|
>> + (self addressAfter: f) < endOfMemory ifTrue:
>> + [freeChunks add: f.
>> + f < lowestFree ifTrue: [lowestFree := f]]].
>> + self allOldSpaceObjectsFrom: lowestFree do:
>> + [:o| | size delta best |
>> + size := self bytesInObject: o.
>> + delta := SmallInteger maxVal.
>> + freeChunks do: [:f| | fs |
>> + ((fs := self bytesInObject: f) >= size) ifTrue:
>> + [delta > (fs - size) ifTrue:
>> + [delta := fs - size. best := f]]].
>> + best ifNotNil:
>> + [movable add: o.
>> + used add: (freeChunks remove: best)]].
>> + ^{ totalFreeOldSpace. movable inject: 0 into: [:s :o| s + (self
>> bytesInObject: o)]. used inject: 0 into: [:s :o| s + (self bytesInObject:
>> o)] }!
>>
>> Item was added:
>> + ----- Method: SpurMemoryManager>>abstractPigCompaction (in category
>> 'compaction - analysis') -----
>> + abstractPigCompaction
>> + "This method answers a rough estimate of compactibility using a
>> pig (a large free chunk)."
>> + <doNotGenerate>
>> + | pig pork moved unmoved nmoved nunmoved |
>> + pig := self findAPig.
>> + pork := self bytesInObject: pig.
>> + moved := unmoved := nmoved := nunmoved := 0.
>> + self allOldSpaceObjectsFrom: pig do:
>> + [:o| | bytes |
>> + bytes := self bytesInObject: o.
>> + bytes <= pork
>> + ifTrue:
>> + [moved := moved + bytes.
>> + nmoved := nmoved + 1.
>> + pork := pork - bytes]
>> + ifFalse:
>> + [unmoved := unmoved + bytes.
>> + nunmoved := nunmoved + 1]].
>> + ^{ self bytesInObject: pig. pork. moved. nmoved. unmoved.
>> nunmoved }!
>>
>> Item was added:
>> + ----- Method: SpurMemoryManager>>biggies (in category 'compaction -
>> analysis') -----
>> + biggies
>> + "This method answers a sorted collection of the objects >=
>> 1,000,000 bytes long,
>> + above the lowest large free chunk, sandwiched between nilObj and
>> the end of memory."
>> + <doNotGenerate>
>> + | lowestFree biggies |
>> + lowestFree := SmallInteger maxVal.
>> + self allObjectsInFreeTreeDo:
>> + [:f| (self addressAfter: f) < endOfMemory ifTrue: [f <
>> lowestFree ifTrue: [lowestFree := f]]].
>> + biggies := SortedCollection new.
>> + self allOldSpaceObjectsFrom: lowestFree do:
>> + [:f|
>> + (self bytesInObject: f) >= 1000000 ifTrue:
>> + [biggies add: f]].
>> + ^{{nilObj hex. #nil}}, (biggies collect: [:f| {f hex. self
>> bytesInObject: f}]), {{endOfMemory hex. #endOfMemory}}!
>>
>> Item was added:
>> + ----- Method: SpurMemoryManager>>compactionIssues (in category
>> 'compaction - analysis') -----
>> + compactionIssues
>> + <doNotGenerate>
>> + "Compaction isn't working well. It rarely moves more than a few
>> tens of kilobytes. Why?
>> + Load an image and before you run it, or just before a GC, run
>> these anaylsis routines.
>> + e.g.
>> + self abstractCompaction #(63230272 75456 63210648)
>> + shows we can move 75456 bytes of objects, but that would use
>> 63210648 of free space.
>> + i.e. there are lots of big free chunks in play, not many small
>> ones that fit the bill.
>> +
>> + self largeFreeChunkDistribution
>> + #( #('16r31C788' #nil)
>> + #('16r1423AC0' 2061864)
>> + #('16r1B705E8' 1515200)
>> + #('16r1D31D20' 2011152)
>> + #('16r1F37818' 1491480)
>> + #('16r2225968' 1450512)
>> + #('16r24C92C8' 48575672) (16r24C92C8 +
>> 48575672) hex '16r531C780' a free chunk
>> + #('16r531C788' #endOfMemory))
>> + shows there's plenty of large free chunks. And the trailing
>> 16-byte free chunk shows coallescing is not working properly.
>> +
>> + self biggies #(#('16r31C788' #nil) #('16r531C788'
>> #endOfMemory))
>> + shows there are no large objects to be moved.
>> +
>> + So... looks like compaction should hold onto the lowest large
>> chunk and preferentially move objects into that.
>> + Let's call it a pig. Compaction needs to whittle away at the
>> pig.
>> +
>> + e.g.
>> + self abstractPigCompaction #(2061864 0 2061864 18759
>> 2018224 34757)
>> + shows we can move 18759 objects that will occupy 2018224 bytes
>> into that
>> + low pig of 2061864 bytes."!
>>
>> Item was added:
>> + ----- Method: SpurMemoryManager>>findAPig (in category 'compaction -
>> analysis') -----
>> + findAPig
>> + "Answer a large low free chuink."
>> + <doNotGenerate>
>> + | pig |
>> + self allObjectsInFreeTreeDo:
>> + [:f|
>> + (self bytesInObject: f) >= 1000000 ifTrue:
>> + [(pig isNil or: [pig > f]) ifTrue:
>> + [pig := f]]].
>> + ^pig!
>>
>> Item was added:
>> + ----- Method: SpurMemoryManager>>largeFreeChunkDistribution (in
>> category 'compaction - analysis') -----
>> + largeFreeChunkDistribution
>> + "This method answers a sorted collection of the free chunks >=
>> 1,000,000 bytes long,
>> + sandwiched between nilObj and the end of memory (ignoring the
>> large chunk often found at the end of the heap)."
>> + <doNotGenerate>
>> + | freeChunks |
>> + freeChunks := SortedCollection new.
>> + self allObjectsInFreeTreeDo:
>> + [:f|
>> + ((self addressAfter: f) < endOfMemory
>> + and: [(self bytesInObject: f) >= 1000000]) ifTrue:
>> + [freeChunks add: f]].
>> + ^{{nilObj hex. #nil}}, (freeChunks collect: [:f| {f hex. self
>> bytesInObject: f}]), {{endOfMemory hex. #endOfMemory}}!
>>
>>
>>
--
best,
Eliot
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