KUMIKO GOTO
2007-Dec-27 15:49 UTC
[Xen-users] Machine time delay in guest domains (Full virtualization)
Hi, I have one question about machine time delay in guest domains (full virtualization). In order to evaluate cpu performance, I applied "SPEC CPU2006" and found that machine time of guest domains is severely delayed from actual time. ->Actual test time : test time measured in guest domains = 4:1 (e.g., Actual test time =40 min, test time measured in guest domain time =10 min) I think that there is some relationship between the number of domains and cores. (please see the following results) Does anyone know why this kind of time delay occurs in Xen? ------------------------------------------------------ <<Environment>> -Host machine has 2 cores (core number 0-1) -Guest OSs: Full virtualization *test 1 4 domains share 2 core (each domain has 2 vcpu) ->result: actual test time : test time measured in guest domains = 4:1 *test 2 2 domains share 1 core and the other 2 domains share the other 1 core. ->result: actual test time : test time measured in guest domains = 2:1 ------------------------------------------------------ Thanks for your kindness. Best, -Kumiko _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Caz Yokoyama
2007-Dec-27 16:40 UTC
RE: [Xen-users] Machine time delay in guest domains (Fullvirtualization)
Hello Goto-san, "SPEC CPU2006" probably refers domain virtual time. Let''s assume you have one Dom0 and 2 DomUs and each one is scheduled 1/3 of processor time. Each one receives 33 clock ticks out of 100 clock ticks. Domain virtual time of DomU is advanced 1/3 of actual clock (wall clock time). Please refer "2.4 Time" of "Xen Interface manual Xen v3.0 for x86" for detail. Thank you. -Caz Yokoyama, caz@caztech.com, CazYokoyama@gmail.com, +1-503-804-1028(m) _____ From: xen-users-bounces@lists.xensource.com [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of KUMIKO GOTO Sent: Thursday, December 27, 2007 7:49 AM To: xen-users@lists.xensource.com Subject: [Xen-users] Machine time delay in guest domains (Fullvirtualization) Hi, I have one question about machine time delay in guest domains (full virtualization). In order to evaluate cpu performance, I applied "SPEC CPU2006" and found that machine time of guest domains is severely delayed from actual time. ->Actual test time : test time measured in guest domains = 4:1 (e.g., Actual test time =40 min, test time measured in guest domain time =10 min) I think that there is some relationship between the number of domains and cores. (please see the following results) Does anyone know why this kind of time delay occurs in Xen? ------------------------------------------------------ <<Environment>> -Host machine has 2 cores (core number 0-1) -Guest OSs: Full virtualization *test 1 4 domains share 2 core (each domain has 2 vcpu) ->result: actual test time : test time measured in guest domains = 4:1 *test 2 2 domains share 1 core and the other 2 domains share the other 1 core. ->result: actual test time : test time measured in guest domains = 2:1 ------------------------------------------------------ Thanks for your kindness. Best, -Kumiko _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
KUMIKO GOTO
2008-Jan-09 12:27 UTC
Re: [Xen-users] Machine time delay in guest domains (Fullvirtualization)
Hi, Caz, Thanks so much for giving me a valuable suggestion. I''m now checking the manual (but it is soooo difficult...) Anyway, I really would like to extend my sincere gratitude to you. :) -kumiko 2007/12/28, Caz Yokoyama <cazyokoyama@gmail.com>:> > Hello Goto-san, > > "SPEC CPU2006" probably refers domain virtual time. Let''s assume you have > one Dom0 and 2 DomUs and each one is scheduled 1/3 of processor time. Each > one receives 33 clock ticks out of 100 clock ticks. Domain virtual time of > DomU is advanced 1/3 of actual clock (wall clock time). Please refer "2.4Time" > of "Xen Interface manual Xen v3.0 for x86" for detail. > > > > Thank you. > > -Caz Yokoyama, caz@caztech.com, CazYokoyama@gmail.com, +1-503-804-1028(m) > ------------------------------ > > *From:* xen-users-bounces@lists.xensource.com [mailto: > xen-users-bounces@lists.xensource.com] *On Behalf Of *KUMIKO GOTO > *Sent:* Thursday, December 27, 2007 7:49 AM > *To:* xen-users@lists.xensource.com > *Subject:* [Xen-users] Machine time delay in guest domains > (Fullvirtualization) > > > > Hi, > > I have one question about machine time delay in guest domains (full > virtualization). > > In order to evaluate cpu performance, I applied "SPEC CPU2006" and found > that > machine time of guest domains is severely delayed from actual time. > ->Actual test time : test time measured in guest domains = 4:1 > (e.g., Actual test time =40 min, test time measured in guest domain time > =10 min) > > I think that there is some relationship between the number of domains and > cores. > (please see the following results) > > Does anyone know why this kind of time delay occurs in Xen? > > ------------------------------------------------------ > <<Environment>> > -Host machine has 2 cores (core number 0-1) > -Guest OSs: Full virtualization > > *test 1 > 4 domains share 2 core (each domain has 2 vcpu) > ->result: actual test time : test time measured in guest domains = 4:1 > > *test 2 > 2 domains share 1 core and the other 2 domains share the other 1 core. > ->result: actual test time : test time measured in guest domains = 2:1 > ------------------------------------------------------ > > Thanks for your kindness. > > Best, > > -Kumiko >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users