From: Jeremy Fitzhardinge Date: Tue, 13 Feb 2007 12:26:20 +0000 (+0100) Subject: [PATCH] i386: Convert i386 PDA code to use %fs X-Git-Tag: v2.6.21-rc1~184^2~88 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=464d1a78fbf8cf6c7fd970e7b3e2db50a320ce28;p=pandora-kernel.git [PATCH] i386: Convert i386 PDA code to use %fs Convert the PDA code to use %fs rather than %gs as the segment for per-processor data. This is because some processors show a small but measurable performance gain for reloading a NULL segment selector (as %fs generally is in user-space) versus a non-NULL one (as %gs generally is). On modern processors the difference is very small, perhaps undetectable. Some old AMD "K6 3D+" processors are noticably slower when %fs is used rather than %gs; I have no idea why this might be, but I think they're sufficiently rare that it doesn't matter much. This patch also fixes the math emulator, which had not been adjusted to match the changed struct pt_regs. [frederik.deweerdt@gmail.com: fixit with gdb] [mingo@elte.hu: Fix KVM too] Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Andi Kleen Cc: Ian Campbell Acked-by: Ingo Molnar Acked-by: Zachary Amsden Cc: Eric Dumazet Signed-off-by: Frederik Deweerdt Signed-off-by: Andrew Morton --- Reading git-diff-tree failed