From mboxrd@z Thu Jan 1 00:00:00 1970 From: anupam.kapoor@gmail.com (Anupam Kapoor) Date: Thu, 19 Feb 2015 17:04:07 +0530 Subject: unlikely compiler flag propagation In-Reply-To: <20150218183801.GA1773@opentech.at> References: <20150218182453.GB21740@kroah.com> <20150218183801.GA1773@opentech.at> Message-ID: <87lhjuxhhs.fsf@fatcat.parallelwireless> To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org >>>>> [2015-02-19T00:08:01+0530]: "Nicholas Mc Guire" (nicholas-mcguire): nicholas-mcguire> On Wed, 18 Feb 2015, Greg KH wrote: ,----[ greg-kh ] | As proof of this, there was a test of the kernel a year or so ago that | measured the placement of the existing likely/unlikely markers in the | kernel and 90% of the usages were wrong and actually slowed down the | processor. `---- ,----[ nicholas-mcguire ] | interesting - would you have a reference to some talk/paper/data/... ? `---- couple of 'slightly' oldish posts: http://blog.man7.org/2012/10/how-much-do-builtinexpect-likely-and.html and http://thread.gmane.org/gmane.linux.kernel/1072767 --- thanks anupam