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Descriptionjohn.haxby@oracle.com
2011-03-30 15:57:52 UTC
Created attachment 488813[details]
Variation of the patch posted upstream to use cpuid 4 rather than cpuid 2 when possible
Description of problem:
The mechanism that sysconf(3) uses to get the various CACHE parameters
fails on the Xen 5670
Version-Release number of selected component (if applicable): 2.12-1.7.el6_0.4
How reproducible:
Every time
Steps to Reproduce:
1. Find a machine whose /proc/cpuinfo starts something like this:
vendor_id : GenuineIntel
cpu family : 6
model : 44
model name : Intel(R) Xeon(R) CPU X5670 @ 2.93GHz
stepping : 2
2. run "getconf -a | grep CACHE"
3. Observe values printed
Actual results:
All the cache parameter values are zero.
Expected results:
Non-zero values for all but the level 4 cache
Additional info:
Recent CPUs no longer have useful cpuid leaf 2 cache descriptors. For this
particular machine, cpuid 2 returns 0x55035a01 0xf0b2ff 0x0 0xca0000 in eax,
ebx, ecx and edx respectively. The 0xff in the least significant byte of
ebx indicates that you need to use cpuid leaf 4. Actually, for all but
somewhat old CPUs you're better off using cpuid leaf 4 anyway (the only
machines I have access to that have a cpuid level less than four are a
"Intel(R) Pentium(R) 4 CPU 1.70GHz" and "Intel(R) Pentium(R) 4 CPU 2.40GHz"
both of which are long past their use-by date).
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.
http://rhn.redhat.com/errata/RHBA-2011-0584.html
Created attachment 488813 [details] Variation of the patch posted upstream to use cpuid 4 rather than cpuid 2 when possible Description of problem: The mechanism that sysconf(3) uses to get the various CACHE parameters fails on the Xen 5670 Version-Release number of selected component (if applicable): 2.12-1.7.el6_0.4 How reproducible: Every time Steps to Reproduce: 1. Find a machine whose /proc/cpuinfo starts something like this: vendor_id : GenuineIntel cpu family : 6 model : 44 model name : Intel(R) Xeon(R) CPU X5670 @ 2.93GHz stepping : 2 2. run "getconf -a | grep CACHE" 3. Observe values printed Actual results: All the cache parameter values are zero. Expected results: Non-zero values for all but the level 4 cache Additional info: Recent CPUs no longer have useful cpuid leaf 2 cache descriptors. For this particular machine, cpuid 2 returns 0x55035a01 0xf0b2ff 0x0 0xca0000 in eax, ebx, ecx and edx respectively. The 0xff in the least significant byte of ebx indicates that you need to use cpuid leaf 4. Actually, for all but somewhat old CPUs you're better off using cpuid leaf 4 anyway (the only machines I have access to that have a cpuid level less than four are a "Intel(R) Pentium(R) 4 CPU 1.70GHz" and "Intel(R) Pentium(R) 4 CPU 2.40GHz" both of which are long past their use-by date).