2013/3/5 Michael Wolf <mjw@xxxxxxxxxxxxxxxxxx>: > Sorry for the delay in the response. I did not see the email > right away. > > On Mon, 2013-02-18 at 22:11 -0300, Marcelo Tosatti wrote: >> On Mon, Feb 18, 2013 at 05:43:47PM +0100, Frederic Weisbecker wrote: >> > 2013/2/5 Michael Wolf <mjw@xxxxxxxxxxxxxxxxxx>: >> > > In the case of where you have a system that is running in a >> > > capped or overcommitted environment the user may see steal time >> > > being reported in accounting tools such as top or vmstat. This can >> > > cause confusion for the end user. >> > >> > Sorry, I'm no expert in this area. But I don't really understand what >> > is confusing for the end user here. >> >> I suppose that what is wanted is to subtract stolen time due to 'known >> reasons' from steal time reporting. 'Known reasons' being, for example, >> hard caps. So a vcpu executing instructions with no halt, but limited to >> 80% of available bandwidth, would not have 20% of stolen time reported. > > Yes exactly and the end user many times did not set up the guest and is > not aware of the capping. The end user is only aware of the performance > level that they were told they would get with the guest. > >> >> But yes, a description of the scenario that is being dealt with, with >> details, is important. > > I will add more detail to the description next time I submit the > patches. How about something like,"In a cloud environment the user of a > kvm guest is not aware of the underlying hardware or how many other > guests are running on it. The end user is only aware of a level of > performance that they should see." or does that just muddy the picture > more?? That alone is probably not enough. But yeah, make sure you clearly state the difference between expected (caps, sched bandwidth...) and unexpected (overcommitting, competing load...) stolen time. Then add a practical example as you made above that explains why it matters to make that distinction and why you want to report it. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
