From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: last_marked array is now ifdef'ed away Date: Sun, 15 Sep 2024 09:01:16 +0300 Message-ID: <86ldzte9qr.fsf@gnu.org> References: <86zfokyp64.fsf@gnu.org> <86ed5pkz53.fsf@gnu.org> <851C7C12-44A1-4661-9EA7-16B0B7209D11@gmail.com> <86a5gbk295.fsf@gnu.org> <8634m2f8ii.fsf@gnu.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="39238"; mail-complaints-to="usenet@ciao.gmane.io" Cc: mattias.engdegard@gmail.com, emacs-devel@gnu.org To: Stefan Kangas Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sun Sep 15 08:02:06 2024 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1spiKk-000A5Z-E2 for ged-emacs-devel@m.gmane-mx.org; Sun, 15 Sep 2024 08:02:06 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1spiK2-0002L5-Ch; Sun, 15 Sep 2024 02:01:22 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1spiK0-0002Kq-Gs for emacs-devel@gnu.org; Sun, 15 Sep 2024 02:01:20 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1spiK0-00050v-7b; Sun, 15 Sep 2024 02:01:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=References:Subject:In-Reply-To:To:From:Date: mime-version; bh=kiDHuKSy5PKrHut/6gvW8LHEaKYHG8ubQz8S6PDzF54=; b=hOORmijrrzut HiY/j3xlFxKOeJbRkBVl8pdT8J9FEbdEv2lIStFzVhPLgNCJSPU98A6rNolbsiyqZQuq89N8Eq+dh E7O5QzWmCB0Edmaz8Hs04uXLu/+Z5fFsBw6zGhGbzgAgMRp4U4/2AJ7j9iRkS1BygpgWy/dKOg+hY 7XwrqMRnD8QbRBDl74kFUyY/xr7j6/0q1n783N3d+p/DJ0AIfzBUK6BUxKkvdEhy7PuhE1XJLsGf2 VmmcGIgWHMrNuh+6TE0g9b84N8fxVxaoqmaVeq02e5x1Bo+bhNTOKWP5lmrek0+jQTTmb0+cv/EM+ Wwvr1WbqchmMyHoY1yoIwA==; In-Reply-To: (message from Stefan Kangas on Sat, 14 Sep 2024 15:50:03 -0700) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:323630 Archived-At: > From: Stefan Kangas > Date: Sat, 14 Sep 2024 15:50:03 -0700 > Cc: emacs-devel@gnu.org > > Eli Zaretskii writes: > > > I'm quite confident that I want this be turned on again. > > Since this affects performance by quite a bit (4.5-6.5 %, reportedly), > how about the suggestion to "hitch it to another existing config option > like ENABLE_CHECKING, or even make this an independent config option"? This feature is useless if it is optional, because its main (perhaps the only) use is when Emacs crashes during GC on a user machine, especially without enough debug info. Crashes during GC are rarely if at all reproducible, so the only hope to investigate them is to look at the objects recorded in the last_marked array, and asking users to rebuild with some non-default option will not help. If we are going to make it a compilation option, we might as well remove it entirely. 5% of slowdown during GC (if that's a well-established number) is a small price to pay for the possibility of investigating rare crashes. A typical GC cycle takes tens or hundreds of milliseconds, so these few percents are just a couple of msec.