UKUUG Linux 2001 — Linux Developers' Conference 29 June - 1 July 2001, Renold Building, UMIST, Manchester

Andrea Arcangeli

vsyscalls

Syscalls such as gettimeofday are very fast internally and get called with a very high frequency by some applications. The overhead of entering and exiting the kernel to run them is very significant. But moving gettimeofday to unprivileged userspace is not feasible because it needs to get information about interrupts and chipsets in the hardware.

Instead, since we cannot move gettimeofday into userspace, we'll see how we moved part of the x86-64 kernel into userspace and what this change means for userspace/glibc/gdb/exceptions.

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