From: David G. <dav...@oc...> - 2006-04-08 12:53:11
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Okay. I got a Xen VPS host, because I can therefore install whatever the hell I want and e.g. recode my vanity website in lisp. So, installed SBCL in it, just playing about. NPTL TLS, as implemented by GLIBC by default, works under xen but has severe performance problems due to the implementation technique. So... recompile glibc with -mno-tls-direct-seg-refs , as indicated in http://wiki.xensource.com/xenwiki/XenSpecificGlibc *** All well and good, but just in case: might sbcl itself be generating native code that use segment offsets in a Xen-unfriendly manner? It might not be at all, but I'm not well-versed enough in sbcl internals to know, or even know where to look. |
From: Juho S. <js...@ik...> - 2006-04-10 06:09:26
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<dav...@oc...> wrote: > NPTL TLS, as implemented by GLIBC by default, works under xen but > has severe performance problems due to the implementation > technique. So... recompile glibc with -mno-tls-direct-seg-refs , as > indicated in http://wiki.xensource.com/xenwiki/XenSpecificGlibc > > *** All well and good, but just in case: might sbcl > itself be generating native code that use segment offsets > in a Xen-unfriendly manner? Not if I understand their description of the problem correctly. Threaded x86 SBCL uses segments a lot (for example on every dynamic variable access), but only with positive offsets. -- Juho Snellman |