On Wed, Oct 16, 2002 at 02:20:42PM +0200, Maciej W. Rozycki wrote: > > It also introduces an indirect call (jump?) overhead. Anyway, you don't > need to sacrifice anything. We may simply assume the universally > compatible way is the R3k one (be it sysmips() or whatever, if it gets > replaced). Then there is the branch-likely way, which requires > branch-likely support (thus excludes R3k-class processors). Then there is > the ll/sc way, which requires ll/sc (thus excludes R3k-class processors > and ones that lack the ll/sc instructions). And you select the minimum > set of features required at the build time. sysmips is history with current glibc since the Linux kernel emulates LL/SC for CPUs that don't have it. This emulation is actually faster than sysmips. (You'd think it's slower because it's one syscall vs. two emulated instructions. But with LL/SC glibc can use test-and-set which enables a more efficient linux-threads mutex implementation.) AFAIK, current Linux distributions based on glibc-2.2.5 were built for R3K be default and thus used sysmips even on platforms which have LL/SC. > > But all that is of interest only, if VR41XX-like platforms > > would use a glibc from a binary distribution like RedHat or > > Debian (I use Debian for development, but have a custom > > compiled glibc for production use). > > I wouldn't care of distributions -- if one really needs optimized > binaries it may make them be build somehow (either by doing the task > oneself or by convincing someone else). OK, that simplifies the issue. I will prepare a patches for Linux and glibc. Regards, Johannes
