Messages in this thread | | | Date | Tue, 18 May 2010 00:36:10 +0200 (CEST) | From | Thomas Gleixner <> | Subject | RE: [PATCH] x86: Export tsc related information in sysfs |
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On Mon, 17 May 2010, Dan Magenheimer wrote: > > OK, so let's invert the sense of the sysfs file and call it (for now) > "tsc_detected_as_UNreliable". Then anytime the kernel detects > a failed warp test (or any other suspicious condition), it changes > the bit from 0 to 1 effectively saying "if you are using rdtsc > against our recommendation, we told you that it might go bad and > it has, so consider yourself warned that some of the timestamps > you've taken since the last time you've checked this flag > may be b*rked" > > IMHO, addressing the issue directly and clearly documenting it > (instead of trying to hide the dirty laundry in the kernel) > will result in far better education of systems programmers > and far fewer end user problems. Which raises another good analogy: > > You are telling teenagers to abstain and I am proposing that we > instead encourage them to use a condom.
Wrong. A vsyscall _is_ the protection which you want them to pull over the rdtsc.
You are basically telling them: Go ahead, but keep in mind to look for that well hidden tag behind the left earlobe which might change suddenly from "no disease" to "infectous".
Thanks,
tglx
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