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1. Feature Overview:
Feature Id: [71058]
a. Name of Feature: [6.2 FEAT] powerpc: re-enable dispatch trace log userspace interface
b. Feature Description
Since the cpu accounting code uses the hypervisor dispatch trace log now when
CONFIG_VIRT_CPU_ACCOUNTING = y, disabled access to it via files in the
/sys/kernel/debug/powerpc/dtl/ directory in that case. This restores those files. To do this, we
now have a hook that the cpu accounting code will call as it processes each entry from the
hypervisor dispatch trace log. The code in dtl.c now uses that to fill up its ring buffer, rather
than having the hypervisor fill the ring buffer directly. This also fixes dtl_file_read() to handle
overflow conditions a bit better and adds a spinlock to ensure that race conditions (multiple
processes opening or reading the file concurrently) are handled correctly.
2. Feature Details:
Sponsor: Power Kernel
Architectures: ppc64,
Arch Specificity: purely arch specific code
Affects Kernel Modules: No
Delivery Mechanism: Backport
Category: kernel
Request Type: Kernel - Enhancement from IBM
d. Upstream Acceptance: Accepted
Sponsor Priority P3
f. Severity: normal
IBM Confidential: No
Code Contribution: IBM code
g. Component Version Target: ---
3. Business Case
Any userspace tools that depend on the /sys/kernel/debug/powerpc/dtl interface will not function
when CONFIG_VIRT_CPU_ACCOUNTING = y. This enables those tools to function again. This also resolves
some bugs with the sysfs interface.
4. Primary contact at Red Hat:
John Jarvis, jjarvis
5. Primary contacts at Partner:
Project Management Contact:
Michael L. Hohnbaum, hbaum.com
Technical contact(s):
NISHANTH ARAVAMUDAN, aravam.com
Comment 2RHEL Program Management
2011-04-07 18:03:59 UTC
Since RHEL 6.1 External Beta has begun, and this bug remains
unresolved, it has been rejected as it is not proposed as
exception or blocker.
Red Hat invites you to ask your support representative to
propose this request, if appropriate and relevant, in the
next release of Red Hat Enterprise Linux.
------- Comment From hohnbaum.com 2011-04-29 14:16 EDT-------
IBM is quitting this feature request as it has been resolved as part of a 6.1 feature:
> Upstream commit is 872e439a45ed4a4bd499bc55cb0dffa74027f749> Argh, it seems this has already been resolved with the patch from BZ 66961 (RH 633515)