Messages in this thread | | | Subject | Re: x86, mce, Use user return notifier in mce | From | Huang Ying <> | Date | Fri, 13 Jan 2012 14:32:32 +0800 |
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On Thu, 2012-01-12 at 17:46 -0800, Tony Luck wrote: > On Thu, Jan 12, 2012 at 4:36 PM, Huang Ying <ying.huang@intel.com> wrote: > > Replace the home-made TIF_MCE_NOTIFY based code in MCE with user > > return notifier. > > When I looked at this before, I found that the existing user return notifier had > the meaning "call a function before THIS CPU returns to user space". Use in KVM > was to update some MSR that needed adjustment before a cpu ran another user > process. > > The MCE code wanted something slightly different: "call a function before THIS > PROCESS returns to user space". So my prototype code from last year made a > whole new set of interfaces - similar in style to the user return > notifier, but with > the MCE semantics. > > At first glance it looks like you are just using the user return > notifier code (perhaps > I'm mis-reading the diff?). This won't work - it's possible for a > context switch, and > then the process that hit the MCE may get moved to another cpu, when it will > be run. Meanwhile we'll execute our function in the context of some > other process.
You are right. User return notifier can not be used for SRAR. I think that may be useful for SRAO. Where we need a way to do notify earlier in case of the corresponding work_queue item is not executed in time.
Best Regards, Huang Ying
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