From: Stanislaw Gruszka Date: Tue, 30 Apr 2013 15:14:42 +0000 (+0200) Subject: sched: Avoid cputime scaling overflow X-Git-Tag: omap-for-v3.10/dt-fixes-for-merge-window~56^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=55eaa7c1f511af5fb6ef808b5328804f4d4e5243;p=pandora-kernel.git sched: Avoid cputime scaling overflow Here is patch, which adds Linus's cputime scaling algorithm to the kernel. This is a follow up (well, fix) to commit d9a3c9823a2e6a543eb7807fb3d15d8233817ec5 ("sched: Lower chances of cputime scaling overflow") which commit tried to avoid multiplication overflow, but did not guarantee that the overflow would not happen. Linus crated a different algorithm, which completely avoids the multiplication overflow by dropping precision when numbers are big. It was tested by me and it gives good relative error of scaled numbers. Testing method is described here: http://marc.info/?l=linux-kernel&m=136733059505406&w=2 Originally-From: Linus Torvalds Signed-off-by: Stanislaw Gruszka Cc: Frederic Weisbecker Cc: rostedt@goodmis.org Cc: Dave Hansen Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20130430151441.GC10465@redhat.com Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed