[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-bugs] [Bug 788] mv /lib/tls confusion
http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=788 ------- Comment #1 from samuel.thibault@xxxxxxxxxxxx 2007-11-27 05:51 ------- Both are. What happens is that on x86, TLS uses direct negative offsets, which can't be safely run natively, so that Xen has to emulate it, which is very slow. To sum it up: 1) TLS libc with direct negative offsets is very slow because Xen has to emulate all libc TLS accesses. 2) non-TLS libc is a bit slow because libc then accesses TLS data `by hand'. 3) TLS libc with indirect negative offsets is less slow because it uses true TLS mecanism, but without requiring Xen emulation. Unfortunately, very few distributions provide 3) (debian does in the libc6-xen package for instance), so that people end up with 1), which is very bad, thus the common advice to mv tls tls.disabled, so as to get into 2). However, that advice doesn't work any more with glibc starting from 2.6, which _requires_ TLS, so that there's no 2) anymore, and people will have to ask their distributions to provide 3). -- Configure bugmail: http://bugzilla.xensource.com/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee. _______________________________________________ Xen-bugs mailing list Xen-bugs@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-bugs
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