Re: [PATCH 0/4] RFC: jump label - (tracepoint optimizations)

From: Roland McGrath
Date: Thu Sep 03 2009 - 17:12:13 EST

> This looks really interesting and desired. Once GCC adds this (or an
> equivalent) feature, i'd love to have your optimization in the
> kernel.

We expect it will be in gcc 4.5 and backported to Fedora's 4.4 pretty soon.
But it's not finalized yet, so we are only doing proof-of-concept so far.

> Basically everything that is optional and touches some very hot
> codepath would be eligible - not just tracepoints.

Sure. Any place you have a load+conditional-jump where that is too costly,
we can make it a nop that costs a only cycle or so. We probably want to
think a little harder about the nicest macro setup we can do to make
employing this trivial in the source.

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