Messages in this thread | | | Date | Tue, 4 Nov 2008 18:05:01 +0100 | From | Andi Kleen <> | Subject | Re: [PATCH RFC/RFB] x86_64, i386: interrupt dispatch changes |
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> not taking into account the cost of cs reading (which I > don't suspect to be that expensive apart from writting,
GDT accesses have an implied LOCK prefix. Especially on some older CPUs that could be slow.
I don't know if it's a problem or not but it would need some careful benchmarking on different systems to make sure interrupt latencies are not impacted.
Another reason I would be also careful with this patch is that it will likely trigger slow paths in JITs like qemu/vmware/etc.
Also code segment switching is likely not something that current and future micro architectures will spend a lot of time optimizing.
I'm not sure that risk is worth the small improvement in code size.
An alternative BTW to having all the stubs in the executable would be to just dynamically generate them when the interrupt is set up. Then you would only have the stubs around for the interrupts which are actually used.
-Andi
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