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More about the disposition of the address space.

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Robert Strandh 10 years ago
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commit 1b9d31142f
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39
Documentation/chap-address-space.tex
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@ -16,13 +16,40 @@ storage must have associated physical disk memory.
The other half of the address space (say the lower half) contains
mainly the global heap, aside from a small amount of space dedicated
to interrupt handlers and other architecture-imposed data structures.
This part of the address space is divided in (roughly two) halves.
Only half of it requires associated physical disk memory. Aside from
the architecture-imposed data structures. The two halves basically map
to the same disk space. The reason for this organization is that it
makes it easy to implement the global garbage collector
The address space for the heap is divided in two halves. Only one
half requires associated physical disk memory. Thus, aside from the
architecture-imposed data structures, the two halves map to the same
disk space. The reason for this organization is that it makes it easy
to implement the global garbage collector
\seechap{chap-garbage-collection}. The method invented by Kermany et
al \cite{Kermany:2006:CCI:1133981.1134023} divides the heap address
space in two halves, but requires physical memory only for a little
more than half of it.
more than half of it.
\refFig{fig-address-space} illustrates how the organization of the
address space might look on a computed equipped with the x86-64
processor. This processor has a theoretical virtual address space of
$2^{64}$ bytes, but the real virtual address space might be limited
to $2^{46}$ bytes. If so, then the middle of the theoretical address
space is not part of the real address space.
\begin{figure}
\begin{center}
\inputfig{fig-address-space.pdf_t}
\end{center}
\caption{\label{fig-address-space}
Address space on x86-64.}
\end{figure}
As \refFig{fig-address-space} illustrates, the available disk space is
typically a small fraction of the possible virtual address space. For
example, $2^{46}$ bytes is $64$ terabytes which is two orders of
magnitude larger than a typical hard disk. In that case, the disk
space is divided (not necessarily in equal parts) between the global
heap and thread-local storage. Furthermore, the size of each
thread-local storage can be configured according to whether a large
number of threads should be possible, or, on the contrary, each thread
should have a large stack.
Main memory is not shown in \refFig{fig-address-space}, simply because
it just works as a demand-paged cache for the available disk space.

94
Documentation/fig-address-space.fig
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@ -0,0 +1,94 @@
#FIG 3.2 Produced by xfig version 3.2.5b
Landscape
Center
Metric
A4
100.00
Single
-2
1200 2
6 2925 3600 4275 4950
6 2925 3900 4275 4950
2 2 0 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 5
3000 3900 4200 3900 4200 4500 3000 4500 3000 3900
4 1 0 50 -1 4 12 0.0000 0 195 1320 3600 4875 space on disks\001
-6
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 4
3600 3750 3600 3600 4200 3600 4200 3750
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 4
3000 3750 3000 3600 3600 3600 3600 3750
2 1 1 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 2
3600 3900 3600 4500
-6
2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
1200 2400 1200 1800 6000 1800 6000 2400 1200 2400
2 2 0 1 0 7 50 -1 45 0.000 0 0 -1 0 0 5
3000 2400 3000 1800 4200 1800 4200 2400 3000 2400
2 1 1 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 2
5700 1800 5700 2400
2 1 1 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 2
5400 1800 5400 2400
2 1 1 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 2
5100 1800 5100 2400
2 1 1 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 2
4800 1800 4800 2400
2 1 1 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 2
4500 1800 4500 2400
2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 4
3000 1650 3000 1500 4200 1500 4200 1650
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 2
0 0 1.00 60.00 120.00
4500 1425 4350 1725
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 2
0 0 1.00 60.00 120.00
4725 1425 4650 1725
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 2
0 0 1.00 60.00 120.00
4950 1425 4950 1725
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 2
0 0 1.00 60.00 120.00
5250 1425 5250 1725
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 2
0 0 1.00 60.00 120.00
5475 1425 5550 1725
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 2
0 0 1.00 60.00 120.00
5700 1425 5850 1725
2 1 1 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 2
2100 1800 2100 2400
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 2
0 0 1.00 60.00 120.00
1650 1425 1650 1725
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 2
0 0 1.00 60.00 120.00
2550 1425 2550 1725
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 4
1200 2550 1200 2700 1800 2700 1800 2550
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 4
2100 2550 2100 2700 2700 2700 2700 2550
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 4
5400 2550 5400 2700 6000 2700 6000 2550
2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2
0 0 1.00 60.00 120.00
0 0 1.00 60.00 120.00
5700 2775 3900 3525
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 1 2
0 0 1.00 60.00 120.00
0 0 1.00 60.00 120.00
2400 2775 3375 3525
2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 1 2
0 0 1.00 60.00 120.00
0 0 1.00 60.00 120.00
1500 2775 3225 3525
4 1 0 50 -1 4 12 0.0000 0 135 105 1200 1650 0\001
4 1 0 50 -1 4 12 0.0000 0 135 105 6000 1650 2\001
4 0 0 50 -1 4 6 0.0000 0 75 120 6075 1500 64\001
4 1 0 50 -1 4 12 0.0000 0 180 660 3675 900 not part\001
4 1 0 50 -1 4 12 0.0000 0 195 1275 3675 1380 address space\001
4 1 0 50 -1 4 12 0.0000 0 150 1005 5100 1125 thread-local\001
4 1 0 50 -1 4 12 0.0000 0 150 525 5100 1365 space\001
4 1 0 50 -1 4 12 0.0000 0 150 315 1650 1125 half\001
4 1 0 50 -1 4 12 0.0000 0 195 420 1650 1365 heap\001
4 1 0 50 -1 4 12 0.0000 0 150 315 2550 1125 half\001
4 1 0 50 -1 4 12 0.0000 0 195 420 2550 1365 heap\001
4 1 0 50 -1 4 12 0.0000 0 195 900 3675 1140 of existing\001
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