| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <727e50150911241017h4bb1c0aex800e8c0ef7eee9fd@mail.gmail.com> Date: Tue, 24 Nov 2009 13:17:09 -0500 From: Aaron Cohen <remleduff@...il.com> To: Brian Gerst <brgerst@...il.com> Cc: Tim Blechmann <tim@...ngt.org>, linux-kernel@...r.kernel.org Subject: Re: [PATCH 0/5] branch hint tweaks On Tue, Nov 24, 2009 at 12:50 PM, Brian Gerst <brgerst@...il.com> wrote: > On Tue, Nov 24, 2009 at 5:54 AM, Tim Blechmann <tim@...ngt.org> wrote: >> hi all, >> >> doing some branch hint profiling of 2.6.31 on my nehalem machine showed >> a few >> incorrect branch hints. >> these patches remove or change the branch hints > > I'm not sure what version of GCC added this, but I wonder if this > option will fix the problem: > > -fno-guess-branch-probability > Do not guess branch probabilities using heuristics. > > GCC will use heuristics to guess branch probabilities if they are > not provided by profiling feedback (-fprofile-arcs). These heuristics > are based on the control flow graph. If some branch probabilities are Is the kernel's use of unlikely typically intended to mean "I consider the following unlikely so please optimize with that expectation" or is meant to indicate "the following is a slow-path so please pessimize it" or both? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists