copy_from_user() loops, in SKAS mode, calls do_op inside the inner loop; do_op acts on 4k at once, so with modern pipelines, the potential cost of the function call can be very big.
Beyond that, we also call setjmp_wrapper, which simply puts a sigjmp_buf on the stack. Wouldn't the code be cleaner if we rip that out, together with the va_arg() calls, and do everything inside do_buffer_op? Doh, those are from userspace headers. However it looks they would be includable from kernel code (no reference to kernel headers), by adding them at the end of the include search path. Also, could I then turn it into a macro taking a param, and then inline the do_op calls (which are very little ones), or at least turn them into normal calls (i.e. faster ones). I feel like the resulting code could even be cleaner to read. Yes, more wasted space, but I think we win in the trade-off. What's your opinion? I'm ready to work on this. -- Paolo Giarrusso, aka Blaisorblade Skype user "PaoloGiarrusso" Linux registered user n. 292729 http://www.user-mode-linux.org/~blaisorblade ------------------------------------------------------- This SF.Net email is sponsored by Oracle Space Sweepstakes Want to be the first software developer in space? Enter now for the Oracle Space Sweepstakes! http://ads.osdn.com/?ad_id=7393&alloc_id=16281&op=click _______________________________________________ User-mode-linux-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
