From: Jose R. <re...@cs...> - 2000-07-07 19:57:13
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If the idea is to increase the performance, why not no change the "int $80" for a "call um_syscall". um_syscall can "communicate" when it's strictly necessary. For example, a getpid could be done locally. This optimization could do te umlinux even faster than the "default" Linux. Suggestions? On Fri, 7 Jul 2000, Chris Lattner wrote: > Currently, syscall entry requires the tracing thread to wake up, munge the > registers around, and do other stuff before the syscall'ing thread > continues in the kernel... I have two ideas to improve syscall > performance: > > 1. Instead of changing EAX to make the syscall do a getpid, why not just > add 2 to the EIP to skip over the int 80? > 2. Additionally, why not change that int 80 to be "ud2" or some other > opcode that will cause a SIGILL? When receiving a sigill, just check for > the magic opcode and if it is set, do the syscall... this would have the > advantage that the ptrace/c-switch overhead would be reduced... > > Does anyone see any problems with these suggestions? I may be interested > in implementing them if not... > > -Chris > > > > _______________________________________________ > User-mode-linux-devel mailing list > Use...@li... > http://lists.sourceforge.net/mailman/listinfo/user-mode-linux-devel > ------------------------------------------------------------------- Jose Renau Ardevol | The great things in life are what they re...@ui... | seem to be. Oscar Wilde ------------------------------------------------------------------- |