Bug 128315
| Summary: | when using smp kernel with one cpu server linux use two cpu | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 3 | Reporter: | giovanni stinco <giovanni.stinco> |
| Component: | kernel | Assignee: | Arjan van de Ven <arjanv> |
| Status: | CLOSED NOTABUG | QA Contact: | Brian Brock <bbrock> |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 3.0 | CC: | petrides, riel |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i686 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2004-07-22 23:43:25 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: | |||
Hello, Giovanni. When a physical CPU that is capable of hyperthreading is used by an SMP kernel, there are indeed two virtual CPUs, each of which can execute a separate process at the same time. The behavior you have described is expected (and desired). |
From Bugzilla Helper: User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040707 Firefox/0.9.2 Description of problem: for some times we keep running a linux box using an smp kernel (kernel-smp-2.4.21-15.0.3.EL.i686.rpm)but the server has just one cpu. when using top or seeing in /proc/cpuinfo we saw two cpu. our server has an intel xeon cpu with Hyper-Threading technology. now we have boot with a non-smp kernel and we see just one cpu (correct) this is always reproducible using a xeon cpu with Hyper-Threading technology and the last smp kernel release. Version-Release number of selected component (if applicable): kernel-smp-2.4.21-15.0.3.EL.i686.rpm How reproducible: Always Steps to Reproduce: 1.boot with a smp-kernel on a single cpu server 2.type "top" display two cpu 3.type "cat /proc/cpuinfo" display two cpu Actual Results: point 2 and 3 always display two cpu Expected Results: the o.s. must show just one cpu Additional info: i think this note is a bit obscure (and we cannot reproduce it anymore because our server are now in prodution enviroment) but... we are running an apache (2.0.50) web server compiled with mpm worker. with the situation described below (smp kernel and one xeon cpu) with have always problem with the treadh (after some time -random time but is always a matter of hours, sometimes minutes- some thread began to use all the cpu resources. in detail: the first "hang" thread use 50% and when the second hang all the cpu was used (50% for the first one and 50% for the second one). N.B.:one thread never use all the cpu resources. after some time others threads began to hang and the cpu resorces are divided equaly over all the hang threads. we had boot whith a non-smp kernel (the last one released for rh ES 3.0) and the apache works well. some notes: apache is the original one taken from the www.apache.org web-sited, non the redhat one so we understand about the non-support policy... but i think the description below can be maybe useful.