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Remove references to arenaalign from the design.

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 Change: 186581
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Gareth Rees 2014-06-13 16:36:40 +01:00
parent 1b7de24015
commit 9edb44cd70
3 changed files with 11 additions and 10 deletions
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10
mps/design/poolamc.txt
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@ -128,8 +128,8 @@ Placement pads are the BEF and LSP pads created in "to-space" when
placing objects into segments. This wasted space is an expected
space-cost of AMC's naive (but time-efficient) approach to placement
of objects into segments. This is normally not a severe problem. (The
worst case is a client that always requests ``ArenaAlign() + 1`` byte
objects: this has a nearly 100% overhead).
worst case is a client that always requests objects that are one byte
larger than the arena grain size: this has a nearly 100% overhead).
Retained pads could be a problem
@ -159,7 +159,7 @@ Small, medium, and large segments
AMC categorises segments as **small** (one page), **medium**
(several pages), or **large** (``AMCLargeSegPAGES`` or more)::
pages = SegSize(seg) / ArenaAlign(arena);
pages = SegSize(seg) / ArenaGrainSize(arena);
if(pages == 1) {
/* small */
} else if(pages < AMCLargeSegPAGES) {
@ -206,8 +206,8 @@ and ignore all others; this would be extremely simple to implement.
But AMC cannot guarantee this, because in the MPS Allocation Point
Protocol the client is permitted to make a large buffer reserve and
then fill it with many small objects. In such a case, AMC must honour
all nails (if the buffer reserve request was an exact multiple of
``ArenaAlign()``), or all nails except to the last object (if there
all nails (if the buffer reserve request was an exact multiple of the
arena grain size), or all nails except to the last object (if there
was a remainder filled with an LSP pad). Because an LSP pad cannot be
distinguished from a client object, and the requested allocation size
is not recorded, AMC cannot distinguish these two conditions at

7
mps/design/poolawl.txt
View file

@ -463,10 +463,11 @@ Internal
_`.fun.awlsegcreate`: Creates a segment of class ``AWLSegClass`` of size at least ``size``.
_`.fun.awlsegcreate.size.round`: ``size`` is rounded up to an
``ArenaAlign`` before requesting the segment.
_`.fun.awlsegcreate.size.round`: ``size`` is rounded up to the arena
grain size before requesting the segment.
_`.fun.awlsegcreate.size.round.justify`: The arena requires that all
segment sizes are aligned to the ``ArenaAlign``.
segment sizes are rounded up to the arena grain size.
_`.fun.awlsegcreate.where`: The segment is allocated using a
generation preference, using the generation number stored in the

4
mps/design/poolmrg.txt
View file

@ -410,8 +410,8 @@ used to be in the object is not accidentally fixed.
_`.init`: Initializes the entry list, the free ring, the ref ring, and
the ``extendBy`` field.
_`.init.extend`: The ``extendBy`` field is initialized to one
``ArenaAlign()`` (usually a page).
_`.init.extend`: The ``extendBy`` field is initialized to the arena
grain size.
_`.init.extend.justify`: This is adequate as the pool is not expected
to grow very quickly.