From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from eggs.gnu.org (eggs.gnu.org [IPv6:2001:470:142:3::10]) by sourceware.org (Postfix) with ESMTPS id B56223858C2F for ; Mon, 19 Dec 2022 14:45:46 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B56223858C2F Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gnu.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gnu.org 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 1p7HOj-0003qF-VZ; Mon, 19 Dec 2022 09:45:45 -0500 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=krE+hTvXqtEzfNZAnn/rscWRDXbSgtFE2POAnjJHGxU=; b=nNqFsgUjBm4d ivakJMmrA2r4NRNVWCCaG2WPFBQciMNnPl/wn/eZwLj1DOaVs2gHiRaj3B+QxHrUZuE8XXUbgq6eQ CIKjFrg7TTUBUPg1chEbufAX/Gvrhg1zQW/NFpxAZSNoUDfntgcko2zVaTPQlfFirWYb5yXIuxn4K 29PvdkPR5p4gW8H/Gk3PwuydXCgG3GL1jJ/KaiLltD/scSrv2eN5XmKSbF+nM5TOU1J2ManKRgKM2 KLx5becKzlqJmPT5RdBiDC8/ATC2FXX2WYJO+v5enSNIuJ+ypBb95SYsjbyy1OejLPqfYG9WUu/n2 o4rSVAD1LGao5+SafyIWPQ==; Received: from [87.69.77.57] (helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p7HOj-0007bX-9D; Mon, 19 Dec 2022 09:45:45 -0500 Date: Mon, 19 Dec 2022 16:45:55 +0200 Message-Id: <835ye7e9jw.fsf@gnu.org> From: Eli Zaretskii To: Luis Machado , Tom Tromey Cc: gdb-patches@sourceware.org In-Reply-To: (message from Luis Machado on Mon, 19 Dec 2022 14:08:27 +0000) Subject: Re: Two observations using GDB 13 snapshot References: <83h6xugc5v.fsf@gnu.org> <58b64bf8-90b6-d080-c060-d03761501199@arm.com> <83k02neezy.fsf@gnu.org> X-Spam-Status: No, score=1.9 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_BARRACUDACENTRAL,SPF_HELO_PASS,SPF_PASS,TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Level: * X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: > Date: Mon, 19 Dec 2022 14:08:27 +0000 > Cc: gdb-patches@sourceware.org > From: Luis Machado > > On 12/19/22 12:48, Eli Zaretskii wrote: > > This build is without std::thread. Maybe it's related? > > Well, if the worker threads are disabled and things are read by a single thread, that may explain some slowness. But I don't think it would be as slow as you describe. > > > > > Does GDB 13 read DWARF debug info significantly differently than > > previous versions? > > > > Do you see this on GNU/Linux, when debugging GDB with itself, if you > > disable multithreaded DWARF reading? > > For a regular build of GDB 13 (threaded), I see a pretty quick startup (about 3.5 seconds) to start gdb within gdb. > > With a GDB 13 built with threading disabled, I see about 15 seconds to do the same. > > Now, I noticed -readnow doesn't seem to use the worker threads for reading symbols, so passing that option slow things down significantly, to the point it takes 2 minutes to read the symbols. > > I don't know if that's on purpose. Thanks. Tom, could you please chime in? What could explain such a slowdown using -readnow and in the MinGW build without worker threads (since GDB 12 didn't use threads, either)? And why -readnow is so different from a GDB built without threading?