From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca (simark.ca [158.69.221.121]) by sourceware.org (Postfix) with ESMTPS id 25E6E3858D1E for ; Fri, 23 Dec 2022 03:34:03 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 25E6E3858D1E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=simark.ca Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=simark.ca Received: from [10.0.0.11] (unknown [217.28.27.60]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPSA id 178761E0D3; Thu, 22 Dec 2022 22:34:01 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=simark.ca; s=mail; t=1671766442; bh=GN9hX/Gf65KcPePmpL8mSDqs2n+iudhnS5NtIXP/CYE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pGqzsXYjnD0Y6h8wplQ745hQgT/ckv1FaqDvVlT8lK/Ag5hOxcbJQ17dy3+ZWWw2X xJyy5agE9uNZYxFNUeWMXqN0lWaBVt36p/8KjQqvYHhD6+mEUKeg55/PYPzqxBkboR +0uln+qO2611n9w/JmOfnEo+qWzMudootafFW2w0= Message-ID: Date: Thu, 22 Dec 2022 22:34:01 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.1 Subject: Re: Two observations using GDB 13 snapshot Content-Language: en-US To: Eli Zaretskii , Tom Tromey Cc: gdb-patches@sourceware.org, luis.machado@arm.com References: <83h6xugc5v.fsf@gnu.org> <58b64bf8-90b6-d080-c060-d03761501199@arm.com> <83k02neezy.fsf@gnu.org> <835ye7e9jw.fsf@gnu.org> <87h6xrks77.fsf@tromey.com> <83mt7idacj.fsf@gnu.org> From: Simon Marchi In-Reply-To: <83mt7idacj.fsf@gnu.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-5.5 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,SPF_HELO_PASS,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 12/19/22 22:26, Eli Zaretskii via Gdb-patches wrote: >> From: Tom Tromey >> Cc: Luis Machado , Tom Tromey , Eli >> Zaretskii >> Date: Mon, 19 Dec 2022 14:18:52 -0700 >> >>>>>>> "Eli" == Eli Zaretskii via Gdb-patches writes: >> >> Eli> Tom, could you please chime in? What could explain such a slowdown >> Eli> using -readnow and in the MinGW build without worker threads (since >> Eli> GDB 12 didn't use threads, either)? And why -readnow is so different >> Eli> from a GDB built without threading? >> >> Just a quick answer for now, I haven't tried to reproduce or >> investigate... >> >> -readnow should not really be affected by the DWARF scanner rewrite. >> With -readnow, all the new code is bypassed anyway. For quite a while >> now, -readnow (when using DWARF anyway) has operated on the principle >> that since gdb is reading full symbols, it might as well not bother with >> partial symbols (or now, the index). >> >> Threads also should not matter here, because only the initial scan can >> use multiple threads. The full symbol reader is single-threaded and >> hasn't changed in any deep way since GDB 12. >> >> It's possible that some other change affected this -- the DWARF reader >> in general sees a lot of patches. I don't know which one it might be >> offhand, though. > > So you are saying that the rewrite of the DWARF scanner could be the > reason for the slowness? > > Let me know if I can provide any additional information that could be > useful in investigating this. Just wondering, do you build with or without optimizations? Simon