10-15-2010
High System CPU Usage
I am running a Dell PE R815 with 4 x AMD 12 core CPUs with 128GB of RAM and a RAID 5 array of 6 SAS disks. This is an HPC application and is definitely CPU bound, however once I run 16 of these processes (thus pinning 16 cores) the work performed slows down dramatically, to maybe 5 or 10% of what it normally is capable of. Top shows that all HPC processes are using 100% CPU but they rather dramatically shift to system usage (rather than user). Here is a vmstat output:
Quote:
$ vmstat -S M 1 10
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
46 0 0 64968 152 50747 0 0 3 41 0 0 11 32 57 0
46 0 0 64967 152 50747 0 0 0 15860 5255 127 6 89 4 0
46 0 0 64967 152 50747 0 0 0 0 5159 104 7 89 4 0
46 0 0 64968 152 50747 0 0 0 0 5153 106 7 89 4 0
46 0 0 64968 152 50747 0 0 0 40 5232 188 7 89 4 0
46 0 0 64968 152 50747 0 0 0 0 5014 102 7 90 3 0
46 0 0 64968 152 50747 0 0 0 4860 4896 107 7 88 5 0
46 0 0 64968 152 50747 0 0 0 0 5125 103 7 90 3 0
46 0 0 64968 152 50747 0 0 0 0 4987 104 7 89 4 0
46 0 0 64968 152 50747 0 0 0 2520 4805 184 7 89 4 0
To me it doesn't look like a RAM or Disk issue, but perhaps an IO or buffering issue. Please help!
-mowmentous
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LEARN ABOUT MOJAVE
isalnum
ISALNUM(3) BSD Library Functions Manual ISALNUM(3)
NAME
isalnum -- alphanumeric character test
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <ctype.h>
int
isalnum(int c);
DESCRIPTION
The isalnum() function tests for any character for which isalpha(3) or isdigit(3) is true. The value of the argument must be representable
as an unsigned char or the value of EOF.
In the ASCII character set, this includes the following characters (preceded by their numeric values, in octal):
060 ``0'' 061 ``1'' 062 ``2'' 063 ``3'' 064 ``4''
065 ``5'' 066 ``6'' 067 ``7'' 070 ``8'' 071 ``9''
101 ``A'' 102 ``B'' 103 ``C'' 104 ``D'' 105 ``E''
106 ``F'' 107 ``G'' 110 ``H'' 111 ``I'' 112 ``J''
113 ``K'' 114 ``L'' 115 ``M'' 116 ``N'' 117 ``O''
120 ``P'' 121 ``Q'' 122 ``R'' 123 ``S'' 124 ``T''
125 ``U'' 126 ``V'' 127 ``W'' 130 ``X'' 131 ``Y''
132 ``Z'' 141 ``a'' 142 ``b'' 143 ``c'' 144 ``d''
145 ``e'' 146 ``f'' 147 ``g'' 150 ``h'' 151 ``i''
152 ``j'' 153 ``k'' 154 ``l'' 155 ``m'' 156 ``n''
157 ``o'' 160 ``p'' 161 ``q'' 162 ``r'' 163 ``s''
164 ``t'' 165 ``u'' 166 ``v'' 167 ``w'' 170 ``x''
171 ``y'' 172 ``z''
RETURN VALUES
The isalnum() function returns zero if the character tests false and returns non-zero if the character tests true.
COMPATIBILITY
The 4.4BSD extension of accepting arguments outside of the range of the unsigned char type in locales with large character sets is considered
obsolete and may not be supported in future releases. The iswalnum() function should be used instead.
SEE ALSO
ctype(3), isalnum_l(3), isalpha(3), isdigit(3), iswalnum(3), ascii(7)
STANDARDS
The isalnum() function conforms to ISO/IEC 9899:1990 (``ISO C90'').
BSD
July 17, 2005 BSD