Hi, I need to get the exact downtime for doing a live migration with ms precision. (I am not bothered about whole migration time which is close to 1 minute.. I need to measure the live migration downtime during which the DomU is out of service.. the figure quoted in the xen documentation says it as ~60 ms.. ) I hope someone must have tried to measure this before. Can you suggest me ideas to measure this? Thank you, Arun _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Arun Babu wrote:> Hi, > I need to get the exact downtime for doing a live migration with ms > precision. > (I am not bothered about whole migration time which is close to 1 > minute.. I need to measure > the live migration downtime during which the DomU is out of service.. > the figure quoted in the xen > documentation says it as ~60 ms.. ) > I hope someone must have tried to measure this before.If you run a benchmark against the server, and measure the server''s throughput at a high granularity and graph it, it should show you the interval that it was down for. I think that is the most realistic way to do this. Regards, Anthony Liguori> Can you suggest me ideas to measure this? > > Thank you, > Arun > ------------------------------------------------------------------------ > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Could you pls suggest any benchmarks that might have been used in the past to do exactly this? thanks hmv On 6/8/06, Anthony Liguori <aliguori@us.ibm.com> wrote:> > Arun Babu wrote: > > Hi, > > I need to get the exact downtime for doing a live migration with ms > > precision. > > (I am not bothered about whole migration time which is close to 1 > > minute.. I need to measure > > the live migration downtime during which the DomU is out of service.. > > the figure quoted in the xen > > documentation says it as ~60 ms.. ) > > I hope someone must have tried to measure this before. > > If you run a benchmark against the server, and measure the server''s > throughput at a high granularity and graph it, it should show you the > interval that it was down for. I think that is the most realistic way > to do this. > > Regards, > > Anthony Liguori > > > Can you suggest me ideas to measure this? > > > > Thank you, > > Arun > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > Xen-devel mailing list > > Xen-devel@lists.xensource.com > > http://lists.xensource.com/xen-devel > > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 6/9/06, Arun Babu <arunbabu.n@gmail.com> wrote:> > Hi, > I need to get the exact downtime for doing a live migration with ms > precision. > (I am not bothered about whole migration time which is close to 1 minute.. > I need to measure > the live migration downtime during which the DomU is out of service.. the > figure quoted in the xen > documentation says it as ~60 ms.. ) > I hope someone must have tried to measure this before.What about the methods and results in our NSDI 2005 paper, don''t they tell you what you need? You can use in tcpdump on an independent machine and log timestamps of packets send from the migrating domain''s IP, in response to fx a flood-ping. You can also sync the two machine''s clocks using NTP and instrument the tools to measure timestamp of domain suspend resp. resume. Jacob _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jacob, Thanks for replying. I did read your paper, which gives the results in detail . Infact I need to do some tests exactly like the ones in your paper..(but not in such detail) The method discussed estimates downtime with the idea of writable working set & information on number of pages dirtied and hence evaluating the count of dirty pages to be transfered during the final stop-copy phase. I am quite new to xen and am not sure how much effort need to be put in to get information on shadow page table, dirty page count etc to repeat the tests you have performed ... Please let me know if we have more detailed information on the method of measuring this! I am currently trying to estimate is based on a simple socket application running on the guest domain, which does an infinite connect()-close() to a service running on original host. When it migrates to the destination, it wont be able to access the service.(i hav my n/w that way) I am using the time of last successful connect() call and first error in connect() to estimate downtime.(approximately) This gives finer values than the ones you suggested - tcpdump with floodping But I have a problem automating in my method: If migration happens exactly after connect() call and gettimeofday() of a successful/failed connect, then no longer the last succesful connect/first failed connect logic holds. (But always i can manually calculate with the dumps of timestamps) It would be of great help if you can suggest a better method! Sorry for a long mail! Arun On 6/11/06, Jacob Gorm Hansen <jacobg@diku.dk> wrote:> > What about the methods and results in our NSDI 2005 paper, don''t they > tell you what you need? > > You can use in tcpdump on an independent machine and log timestamps of > packets send from the migrating domain''s IP, in response to fx a > flood-ping. > > You can also sync the two machine''s clocks using NTP and instrument > the tools to measure timestamp of domain suspend resp. resume. > > JacobOn 6/9/06, Arun Babu <arunbabu.n@gmail.com> wrote:> > Hi, > I need to get the exact downtime for doing a live migration with ms > precision. > (I am not bothered about whole migration time which is close to 1minute..> I need to measure > the live migration downtime during which the DomU is out of service.. the > figure quoted in the xen > documentation says it as ~60 ms.. ) > I hope someone must have tried to measure this before._______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel