From: Suravee Suthikulpanit Date: Mon, 18 Jan 2010 17:25:45 +0000 (-0600) Subject: oprofile/x86: implement lsfr pseudo-random number generator for IBS X-Git-Tag: v2.6.34-rc1~264^2~6 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f125be1469303f7b9324447f251d74a0da24952f;p=pandora-kernel.git oprofile/x86: implement lsfr pseudo-random number generator for IBS This patch implements a linear feedback shift register (LFSR) for pseudo-random number generation for IBS. For IBS measurements it would be good to minimize memory traffic in the interrupt handler since every access pollutes the data caches. Computing a maximal period LFSR just needs shifts and ORs. The LFSR method is good enough to randomize the ops at low overhead. 16 pseudo-random bits are enough for the implementation and it doesn't matter that the pattern repeats with a fairly short cycle. It only needs to break up (hard) periodic sampling behavior. The logic was designed by Paul Drongowski. Signed-off-by: Suravee Suthikulpanit Signed-off-by: Robert Richter --- Reading git-diff-tree failed