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SubjectRe: [PATCH RFC/RFB] x86_64, i386: interrupt dispatch changes
[Andi Kleen - Tue, Nov 04, 2008 at 06:05:01PM +0100]
| > 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
|

Thanks a lot for comments, Andi!

- Cyrill -


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