From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Landman Subject: Re: crush: straw is dead, long live straw2 Date: Fri, 12 Dec 2014 11:39:08 -0500 Message-ID: <548B1A2C.2050605@gmail.com> References: <20141212091408.GN4150@thinkpad.thebehrens.net> <548B0C16.4000509@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ig0-f174.google.com ([209.85.213.174]:50468 "EHLO mail-ig0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933666AbaLLQjL (ORCPT ); Fri, 12 Dec 2014 11:39:11 -0500 Received: by mail-ig0-f174.google.com with SMTP id hn15so1745318igb.1 for ; Fri, 12 Dec 2014 08:39:10 -0800 (PST) In-Reply-To: Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Sage Weil Cc: Thorsten Behrens , ceph-devel@vger.kernel.org On 12/12/2014 11:20 AM, Sage Weil wrote: > > We can't use floating point. The code needs to run in the kernel. We also > need the rseults to be perfectly deterministic and consistent across all > architectures; I'm not sure if all floating point implementations (and log > implementations) will do that? Nope ... that is a whole different subject. Ok, why not start looking at what some of the GFX folks do? https://graphics.stanford.edu/~seander/bithacks.html#IntegerLog