Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263167AbUDAUvs (ORCPT ); Thu, 1 Apr 2004 15:51:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263163AbUDAUv1 (ORCPT ); Thu, 1 Apr 2004 15:51:27 -0500 Received: from barry.mail.mindspring.net ([207.69.200.25]:45870 "EHLO barry.mail.mindspring.net") by vger.kernel.org with ESMTP id S263161AbUDAUvV (ORCPT ); Thu, 1 Apr 2004 15:51:21 -0500 To: ak@suse.de, gcc@gcc.gnu.org, linux-kernel@vger.kernel.org Subject: Re: Linux 2.6 nanosecond time stamp weirdness breaks GCC build Message-Id: <20040401205133.6C94F4B104@berman.michael-chastain.com> Date: Thu, 1 Apr 2004 15:51:33 -0500 (EST) From: mec.gnu@mindspring.com (Michael Elizabeth Chastain) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1436 Lines: 41 Andi Kleen writes: > The solution from back then I actually liked best was to just round > up to the next second instead of rounding down when going from 1s > resolution to ns. (My understanding of kernel internals is way rusty, so if I am talking nonsense here, just hit me with a cluestick or ignore me or something). Ummm, I think that will just fail in the converse way if insn-conditions.o is retained in the inode cache while insn-conditions.c is dropped from the cache? That is, consider these time-stamps: insn-conditions.c SSSS.NS1 insn-conditions.o SSSS.NS2 Where SSSS is the same value on both files, and NS2 > NS1. According to Ulrich, the current problem is that insn-conditions.o is dropped from the cache, so NS2 becomes 0, and insn-conditions.o becomes older than insn-conditions.c. With your patch, suppose that insn-conditions.c is dropped from the cache, while insn-conditions.o remains. Then the timestamps will be: insn-conditions.c SSSS+1.0 insn-conditions.o SSSS.NS2 We lose again, insn-conditions.c has become newer than insn-conditions.o. insn-conditions.c is a generated file so I think this can actually happen during a gcc build. Michael C - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/