Bug 647949
Summary: | Wrong /sys/devices/system/cpu/cpu*/cache/index4/shared_cpu_map for L3 and L2 cache on HP Integrity BL870c box with 2 Intel Itanium2 9140N processors | ||||||
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Product: | Red Hat Enterprise Linux 5 | Reporter: | Jiri Hladky <jhladky> | ||||
Component: | kernel | Assignee: | Prarit Bhargava <prarit> | ||||
Status: | CLOSED WONTFIX | QA Contact: | Red Hat Kernel QE team <kernel-qe> | ||||
Severity: | medium | Docs Contact: | |||||
Priority: | low | ||||||
Version: | 5.6 | CC: | bmarson, Brice.Goglin, dshaks, jarod, mzywusko, rmusil | ||||
Target Milestone: | rc | ||||||
Target Release: | --- | ||||||
Hardware: | Unspecified | ||||||
OS: | Unspecified | ||||||
Whiteboard: | |||||||
Fixed In Version: | Doc Type: | Bug Fix | |||||
Doc Text: | Story Points: | --- | |||||
Clone Of: | Environment: | ||||||
Last Closed: | 2011-02-24 13:30:49 UTC | Type: | --- | ||||
Regression: | --- | Mount Type: | --- | ||||
Documentation: | --- | CRM: | |||||
Verified Versions: | Category: | --- | |||||
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||
Cloudforms Team: | --- | Target Upstream Version: | |||||
Embargoed: | |||||||
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Description
Jiri Hladky
2010-10-29 22:49:44 UTC
Actually, I think the L3 cache in this Itanium is not shared between cores. There are two 9MB L3 caches, one per core, 18MB total. So index4/shared_cpu_map should contain 2 bits (2 threads of a core), not 4 bits (4 threads of 2 cores of a socket). Hi Brice, thanks for the correction. I have been searching Intel web site for the detailed specification but without success.Finally I have found this link: http://www.xbitlabs.com/news/cpu/display/20071031210033.html# There are indeed 2 9MB L3 caches, one per each core, 18MB total. index4/shared_cpu_map should contain 2 bits (2 threads of a core). Thanks Jirka No customer has complained about this so I'm inclined to leave it as is. AFAICT, this does not impact performance. P. |