Messages in this thread | | | Date | Sun, 17 May 2009 21:46:15 +0200 | From | devzero@web ... | Subject | Re: Where do we stand with the Xen patches? |
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> >> As in the past, my main worry is performance overhead of paravirt in > >> general. > >> > >> The patches that dont affect any native kernel fast path are > >> probably OK (but still pending final review). > >> > >> Regarding patches that do change the fastpath i'll do a round of > >> measurements of CONFIG_PARAVIRT against !CONFIG_PARAVIRT kernels, > >> and make up my mind based on that. > >> > >> You could accelerate this by sending some "perf stat" hard numbers > >> to give us an idea about where we stand today. > >> > >> Ingo > > > > maybe this is iust a stupid comment (please forgive, i?m no advanced kernel > > hacker), but can?t the code inserted by the patches and which changes the > > fastpath just #IFDEF`ed at the critical offsets ? (as building a dom0 kernel is > > just another build target, isn`t it ?) > > no, if dom0 is going to be widely deployed, it will be because the distros > turn on dom0 support by default. as a result any penalties due to xen > support will be felt by all users of those distros (even if they don't use > xen) > > David Lang
so what?
print a huge warning on boot that running dom0 for xen may affect performance and that you should better run a normal kernel instead if you don`t use xen , and you`re done.
or is maintaining two different kernel packages a problem?
if so, instead of using IFDEF`s, can`t the critical path`s being generously circumvented by default, (if, else...), needing some dom0 kernel bootparam to be activated (i.e. use the kernel as dom0 kernel) ?
or is this too short-sighted view of the things ?
regards roland
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