Bug 173825 - irqbalance needs to support >32 CPUs
irqbalance needs to support >32 CPUs
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel-utils (Show other bugs)
All Linux
medium Severity high
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Assigned To: Jim Paradis
Brian Brock
Depends On:
Blocks: 168429
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Reported: 2005-11-21 12:57 EST by Jim Paradis
Modified: 2007-11-30 17:07 EST (History)
2 users (show)

See Also:
Fixed In Version: RHBA-2006-0005
Doc Type: Bug Fix
Doc Text:
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Last Closed: 2006-03-07 13:07:16 EST
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RHEL 7.3 requirements from Atomic Host:
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Description Jim Paradis 2005-11-21 12:57:24 EST
As it is currently written, the irqbalance utility can only support up to 32
CPUs.  There are two issues involving /proc entries that need to be fixed to
address this. 

(1) /proc/irq/<nnn>/smp_affinity format.  This entry contains a hex-formatted
bitmap of the CPUs on which a given interrupt may be delivered.  The current
irqbalance only supports a single 32-bit word format for this file, which limits
us to 32 CPUs.  With more than 32 CPUs, this file consists of several longwords
seprated by commas.  The code that parses and writes this file must be enhanced
to support this extended format.

(2) /proc/interrupts format.  While the overall format of /proc/interrupts is
unchanged, a large number of CPUs could be an issue.  This file has one row per
interrupt and one column per CPU.  A large number of CPUs could make for very
long lines, which irqbalance may not be able to handle (it hard-codes the max
line length at 1024).  Again, we need to make sure this can support as many CPUs
as we're going to support.
Comment 1 Tim Burke 2005-11-21 13:06:56 EST
putting on U3 canfix list.
We're already changing this package for other items, it microcode-ctl. So it
doesn't add another package which wasn't previously planned.
This is needed for the support of > 64 cpus.
Comment 2 Jay Turner 2006-02-03 12:03:44 EST
What testing was done to verify this is working as expected?  Do we have any
testing results from partners?
Comment 4 Red Hat Bugzilla 2006-03-07 13:07:17 EST
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 the 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.


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