Bug 114987
| Summary: | Very poor task switching on average load | ||||||||
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| Product: | [Retired] Red Hat Linux | Reporter: | Nicolas Barry <boozai> | ||||||
| Component: | kernel | Assignee: | Ingo Molnar <mingo> | ||||||
| Status: | CLOSED NEXTRELEASE | QA Contact: | Brian Brock <bbrock> | ||||||
| Severity: | high | Docs Contact: | |||||||
| Priority: | medium | ||||||||
| Version: | 9 | CC: | riel | ||||||
| Target Milestone: | --- | ||||||||
| Target Release: | --- | ||||||||
| Hardware: | athlon | ||||||||
| OS: | Linux | ||||||||
| Whiteboard: | |||||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||||
| Doc Text: | Story Points: | --- | |||||||
| Clone Of: | Environment: | ||||||||
| Last Closed: | 2004-08-18 11:41:47 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: | |||||||||
| Attachments: |
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Created attachment 97484 [details]
Source code of test program
Can you attach the watchdog script too please? Created attachment 97498 [details]
Watchdog script : detects lags of more than 2 seconds
Forgot to post the watchdog script earlier
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Description of problem: We have a set of multithreaded processes running on Redhat 9 machines. When there is some load, it seems that only a few threads inside certain processes get to be executed in a fair way. Certain threads, in particular watchdog threads, that sleep most of the time, timeout the entire system. This problem does not occur on a stock 2.4.x kernel, we tried the latest development 2.4 kernel, and couldn't reproduce the problem. I tested this problem on a variety of systems, one is an athlon single processor, and pentium 3 single and dual processor. Version-Release number of selected component (if applicable): 2.4.20-27.9 or any 2.6.1 through 2.6.2 kernels How reproducible: Very easily using the test program combined with the watchdog script. Steps to Reproduce: 0. Compile cputest with gcc -pthread -D_REENTRANT -lm cputest.c -o cputest 1. Start the watchdog script in a shell 2. Start the test program: ./cputest 20 10000 1000 512 3. Watch the output of the watchdog script Actual results: An output that looks like >>>>>>> delta = 3 Tue Jan 27 15:31:22 PST 2004 >>>>>>> delta = 4 Tue Jan 27 15:31:27 PST 2004 >>>>>>> delta = 4 Tue Jan 27 15:31:34 PST 2004 >>>>>>> delta = 6 Tue Jan 27 15:31:54 PST 2004 >>>>>>> delta = 6 Tue Jan 27 15:32:04 PST 2004 >>>>>>> delta = 20 Tue Jan 27 15:32:13 PST 2004 meaning, in that case, that I got a 20 seconds "freeze" of the watchdog script that ended at 15:32:13 Expected results: There should be no freezes like this, regardless of the load, as the watchdog script needs a very minimal number of cycles to execute every second. Additional info: