A bit like the VDSO in reverse:
Posted Feb 16, 2006 14:27 UTC (Thu) by mingo
In reply to: A bit like the VDSO in reverse:
Parent article: Robust futexes - a new approach
correct - this is about a complex and constantly changing userspace data structure being parsed by the kernel in certain cases. This is not the usual 'pass info the kernel' or 'pass info to userspace' kernel<->userspace data interaction that we normally do.
you are also right that there is a single (very fast) syscall per thread-lifetime. While this is already quite close to 'zero cost', and it is alot cheaper than the other solutions presented before, we could speed this up further by passing this pointer to sys_clone() - that would eliminate the extra syscall in the case of pthread_create().
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