Wiki code for lgrpinfo(1)

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1: == lgrpinfo(1): tool for displaying lgroup hierarchy
2: 
3: The lgrpinfo command prints information about the locality group (lgroup)
4: hierarchy, contents, and characteristics.
5: 
6: An lgroup represents the set of CPU and memory hardware devices that are at most
7: some distance (latency) apart from each other. All lgroups in the system are
8: identified by a unique integer called an //lgroup ID//. The lgroups are organized
9: into a hierarchy to facilitate finding the nearest resources. Leaf lgroups
10: contains set of resources that are closest to each other. Each parent lgroup in
11: the hierarchy contains the resources of its child lgroups plus their next
12: nearest resources. Finally, the root lgroup contains all the resources in the
13: domain within the largest latency.
14: 
15: A Uniform Memory Access (UMA) machine will simply be represented by the root
16: lgroup. A Non Uniform Memory Access (NUMA) machine is represented by a hierarchy
17: of lgroups to show the corresponding levels of locality. For example, a NUMA
18: machine with two latencies (local and remote) will have an lgroup hierarchy
19: consisting of two levels with its leaves and the root.
20: 
21: Every application thread is assigned a //home// lgroup. When the system needs to
22: allocate a CPU or memory resource for the thread, it searches for available
23: resources in its home lgroup and continues up the lgroup hierarchy until it
24: finds one if necessary.
25: 
26: The [[lgrpinfo(1)>>attach:lgrpinfo]] is a Perl script that requires [[Solaris::Lgrp>>../perl_lgrp]] module. It uses  [[liblgrp(3LIB)>>http://docs.sun.com/app/docs/doc/816-5173/6mbb8adu6?a=view]] API to get the information from the system and displays it in the human-readable form.
27: 
28: Example output of //lgrpinfo -Ta// on a 4-CPU AMD system:
29: 
30: {{{
31:     $ lgrpinfo -Ta
32:     0
33:     |~-- 5
34:     |   CPUs: 0-2
35:     |   Lgroup resources:   1-3 (CPU);  1-3 (memory)
36:     |   latency: 88
37:     |   {{code}}~-- 1
38:     |       CPU: 0
39:     |       Memory: installed 3839 Mb,  allocated 474 Mb,  free 3365 Mb
40:     |       Load:    0
41:     |       latency: 54
42:     |~-- 6
43:     |   CPUs: 0 1 3
44:     |   Lgroup resources:   1 2 4 (CPU);  1 2 4 (memory)
45:     |   latency: 88
46:     |   {{/code}}~-- 2
47:     |       CPU: 1
48:     |       Memory: installed 4096 Mb,  allocated 26 Mb,  free 4070 Mb
49:     |       Load:    0
50:     |       latency: 54
51:     |~-- 7
52:     |   CPUs: 0 2 3
53:     |   Lgroup resources:   1 3 4 (CPU);  1 3 4 (memory)
54:     |   latency: 88
55:     |   {{code}}~-- 3
56:     |       CPU: 2
57:     |       Memory: installed 4096 Mb,  allocated 14 Mb,  free 4082 Mb
58:     |       Load:    1
59:     |       latency: 54
60:     {{/code}}~-- 8
61:         CPUs: 1-3
62:         Lgroup resources:   2-4 (CPU);  2-4 (memory)
63:         latency: 88
64:         `~-- 4
65:             CPU: 3
66:             Memory: installed 4096 Mb,  allocated 16 Mb,  free 4080 Mb
67:             Load:    0
68:             latency: 54
69: }}}
70: 
71: === Documents
72: 
73: * [[lgrpinfo(1)>>attach:lgrpinfo]] man page
74: 
75: * [[PSARC proposal (draft)>>attach:lgrpinfopsarc.txt]]
76: 
77: NOTE: The lgrpinfo tool is provided under the rems of the [[OpenSolaris CDDL License>>Main.licensing]].
78: 
79: 
80: === Code
81: 
82: * [[Perl script>>lgrpinfo]]
83: 
84: 
85: === Issues
86: 
87: * Need to verify that it works correctly on systems which have nodes without CPUs or memory
88: 
89: - lgrpinfo -m -u <unit> rounds to nearest integer <unit>, so it will print 0 Gb when there is 512 Mb if <unit> is "g" (for gigabytes).  Should it display fractional sizes (eg. 0.5 Gb instead of 0 Gb for 512 Mb)? (Will not fix)
90: 
91: * Confusing when latency info is printed or not printed.  Lgroup latency values printed by default and latency table printed with -l except with -T (Fixed with the introduction of -L option)
92: 
93: * Need to fix usage message and man page to explain default set of options correctly (Fixed)
94: 
95: * Usage message has spelling errors (eg. "lgoups" instead of "lgroups") (Fixed)
96: 
97: * Need to document -L option and behavior of -C, -P, and -I with no arguments
98:   (Fixed)
99: 
100: * Default behavior doesn’t match man page (Fixed)
101:    * Does -t -c -m -u m -r -l all with no options (this should include -e too)
102:    * Does -L with -Ta
103: 
104: * Need to update examples in man page (Fixed)
105: 
106: * Prints memory and latency for root lgroup on UMA machine.  Shouldn’t it print CPUs and should it print what it does for a leaf since root is the root and a leaf lgroup at the same time?  Need to just print 0 to be consistent with -T on NUMA machines.
107: 
108: * Display caller’s view by default and OS view of lgroups when -G option given (Fixed)
109: 
110: === Comments
111: 
112: Please send your comments and suggestions to the [[discussion forum>>http://www.opensolaris.org/jive/forum.jspa?forumID=26]].
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