Bug 4056
Summary: | anomalous user time from clock(3)/times(3)/setitimer(3) on SMP alpha | ||
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Product: | [Retired] Red Hat Linux | Reporter: | Jeff Johnson <jbj> |
Component: | kernel | Assignee: | Cristian Gafton <gafton> |
Status: | CLOSED CURRENTRELEASE | QA Contact: | |
Severity: | medium | Docs Contact: | |
Priority: | medium | ||
Version: | 6.0 | CC: | gafton, ken.crandall, michael.waite |
Target Milestone: | --- | ||
Target Release: | --- | ||
Hardware: | alpha | ||
OS: | Linux | ||
Whiteboard: | |||
Fixed In Version: | Doc Type: | Bug Fix | |
Doc Text: | Story Points: | --- | |
Clone Of: | Environment: | ||
Last Closed: | Type: | --- | |
Regression: | --- | Mount Type: | --- |
Documentation: | --- | CRM: | |
Verified Versions: | Category: | --- | |
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
Cloudforms Team: | --- | Target Upstream Version: | |
Embargoed: |
Description
Jeff Johnson
1999-07-15 16:17:20 UTC
Note: this problem is present in glibc-2.1.2 (from Ken Crandall). *** Bug 3838 has been marked as a duplicate of this bug. *** There seems to be a problem with process CPU time display on Linux Alpha systems. The process CPU time increments MUCH faster than wall clock time. The CPU time seems to be about 8 to 10 times faster than wall clock time. You can see this with either a "w" display or a "top" display. For example: [hibbert@spe85 ~]$ w Unknown HZ value! (2048) Assume 1024. 3:47pm up 38 min, 5 users, load average: 1.85, 1.27, 0.73 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT root tty1 - 3:09pm 0.00s 1.02s 0.78s talk cnbc root tty2 - 3:39pm 3:29 0.27s 0.14s -bash cnbc pts/0 VIM.BOLTZ.CS.CMU 3:29pm 0.00s 7.03s 0.55s talk root@spe85 hibbert pts/1 tnt1-159.mtco.co 3:44pm 1:55 15:12 15:11 ./setiathome hibbert pts/2 tnt1-159.mtco.co 3:45pm 0.00s 0.43s 0.06s w Note that the first hibbert process has been logged in for only about 2 minutes, yet has used 15 minutes of CPU time. I know Alpha's are fast, but I didn't think they could bend time! This bug does not appear to be a problem for the Proliant Intel based system. I have been trying to track down this problem. I suspect there is a system function that convers CPU ticks to seconds that is assuming the Alpha is using the common PC interval clock rate of 100/second rather than the 1K/second rate that most Alpha's actually use. I have not been able to locate the source code for the "w" program to see what function calls it uses to convert the time. This appears to be a 2.2.5smp kernel bug: the user time returned by the times system call seems to be incorrect. This should be fixed in a later release of the linux kernel, which I am putting out now. There is a kernel-2.2.10-3 now in the tree - can anybody tell me if the problem is still there so that I can get rth on board? |