From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 8526 invoked by alias); 2 Apr 2004 19:16:49 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 8480 invoked by alias); 2 Apr 2004 19:16:47 -0000 Date: Fri, 02 Apr 2004 19:16:00 -0000 Message-ID: <20040402191647.8479.qmail@sources.redhat.com> From: "geoffk at apple dot com" To: gcc-bugs@gcc.gnu.org In-Reply-To: <20040303083528.14400.schmid@snake.iap.physik.tu-darmstadt.de> References: <20040303083528.14400.schmid@snake.iap.physik.tu-darmstadt.de> Reply-To: gcc-bugzilla@gcc.gnu.org Subject: [Bug pch/14400] Cannot compile qt-x11-free-3.3.0 X-Bugzilla-Reason: CC X-SW-Source: 2004-04/txt/msg00205.txt.bz2 List-Id: ------- Additional Comments From geoffk at apple dot com 2004-04-02 19:16 ------- Subject: Re: Cannot compile qt-x11-free-3.3.0 On 02/04/2004, at 7:17 AM, Ian Lance Taylor wrote: > "geoffk at apple dot com" writes: > >> On Mar 29, 2004, at 11:06 PM, Ian Lance Taylor wrote: > >>> PR 14206 is fixed on mainline by RTH's patch. For 3.4 I put in a doc >>> fix. > >> I've now caught up enough that I read RTH's patch (I've been on >> vacation). Yes, that patch should fix this problem too. I'd suggest >> backporting it to 3.4. > > We can do that. However, I am still troubled by the fact that the > default fallback for gt_pch_get_address/gt_pch_use_address is > unreliable. RTH's patch may well fix the problem on GNU/Linux for all > but strange cases. But it seems to me that with that patch PCH will > work reasonably on GNU/Linux and on Darwin, but will not work reliably > on any other system. > > That is, I don't think that any system can reliably use > mmap_gt_pch_get_address/mmap_gt_pch_use_address, although they are the > default functions on a system which supports mmap. > > Is it better to have PCH which unpredictably fails or PCH which > reliably fails? Right now, in mainline, I think we have the former, > except on GNU/Linux and Darwin. I think that PCH that fails on one case out of a thousand is better than PCH that fails in one thousand cases out of one thousand. However, it would be better if we could make failure even less frequent by tweaking the heuristic. Ian, you've studied the problem, do you have any suggestions for a better heuristic? Maybe gt_pch_get_address should map, say, 32M of unused memory before trying to allocate space for the PCH. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14400