From mboxrd@z Thu Jan 1 00:00:00 1970 From: Noah Watkins Subject: Re: towards a user-mode diagnostic log mechanism Date: Tue, 10 Jan 2012 17:06:55 -0800 Message-ID: <4F0CE0AF.6090702@cs.ucsc.edu> References: <4EEFF614.8040207@dreamhost.com> <4F0CDA9A.4070500@cs.ucsc.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-01.cse.ucsc.edu ([128.114.48.32]:38545 "EHLO mail-01.cse.ucsc.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754211Ab2AKBG2 (ORCPT ); Tue, 10 Jan 2012 20:06:28 -0500 In-Reply-To: Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Tommi Virtanen Cc: Noah Watkins , Colin McCabe , Mark Kampe , ceph-devel@vger.kernel.org On 1/10/12 5:04 PM, Tommi Virtanen wrote: > On Tue, Jan 10, 2012 at 16:40, Noah Watkins wrote: >> >> Older Linux kernels force a thread into the kernel when calling gettimeofday >> adding enormous overhead relative to the newer vsyscall implementations that >> evaluate gettimeofday within userspace. > > So turning debug to full blast on older kernels will be painful. I'm > personally ok with that, especially when the alternative is > implementing all of the TSC logic myself. This is really complex code, > and somebody went through the effort of solving the hard problems for Yeh, that was just a bit of fyi noise. > us -- let's use their code! I definitely agree :)