From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EB9DEC43460 for ; Thu, 1 Apr 2021 14:04:15 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AA57461285 for ; Thu, 1 Apr 2021 14:04:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA57461285 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.104515.199965 (Exim 4.92) (envelope-from ) id 1lRxva-0001ZX-KW; Thu, 01 Apr 2021 14:04:06 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 104515.199965; Thu, 01 Apr 2021 14:04:06 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lRxva-0001ZQ-Gc; Thu, 01 Apr 2021 14:04:06 +0000 Received: by outflank-mailman (input) for mailman id 104515; Thu, 01 Apr 2021 14:04:06 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lRxva-0001ZL-0B for xen-devel@lists.xenproject.org; Thu, 01 Apr 2021 14:04:06 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lRxvY-0007IN-NU; Thu, 01 Apr 2021 14:04:04 +0000 Received: from 54-240-197-239.amazon.com ([54.240.197.239] helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1lRxvY-0007p5-HG; Thu, 01 Apr 2021 14:04:04 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=oxS3dMoshd19B3V90o3bmPWkqypn36Zp+eVdVJW1c4E=; b=DkDO9Rlno7NY5lYiCLZ7bBxP7X vlz9rOT7z1KvqT4SMU23FIwKKlETSMy1V9pkwtE+4xTDmBZcPVpnQegio9UEzJKaTICvhPVf84HLm JSY4fwB4lLmsxWimFO7ov096OovcG1wvF18i05MfPgsBGQNoa71vf6q/QR6g2OJaTj4Y=; Subject: Re: [PATCH 00/23] further population of xen/lib/ To: Jan Beulich Cc: Andrew Cooper , George Dunlap , Ian Jackson , Stefano Stabellini , Wei Liu , "xen-devel@lists.xenproject.org" References: <27916fa0-9ebd-a49a-bbb9-1ef47c2b5bf6@xen.org> <4f745d03-baa8-e9e6-692c-f9c9f401b766@suse.com> From: Julien Grall Message-ID: <6a38f0db-938b-fd13-48e6-6b538c85fe42@xen.org> Date: Thu, 1 Apr 2021 15:04:02 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <4f745d03-baa8-e9e6-692c-f9c9f401b766@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Hi Jan, On 01/04/2021 14:43, Jan Beulich wrote: > On 01.04.2021 13:54, Julien Grall wrote: >> On 01/04/2021 11:14, Jan Beulich wrote: >>> This is to dissolve / move xen/common/lib.c and xen/common/string.c. >>> One benefit of moving these functions into an archive is that we can >>> drop some of the related __HAVE_ARCH_* #define-s: By living in an >>> archive, the per-arch functions will preempt any loading of the >>> respective functions (objects) from the archive. (Down the road we >>> may want to move the per-arch functions into archives as well, at >>> which point the per-arch archive(s) would need to be specified ahead >>> of the common one(s) to the linker.) >> >> While I think it is a good idea to move code in xen/lib, I am not >> convinced that having a single function per file is that beneficial. >> >> Do you have numbers showing how much Xen will shrink after this series? > > In the default build, from all I was able to tell, there's one function > that's unused (strspn(), as mentioned in the respective patch description). > I don't think I've been claiming any space savings here, though, so I You didn't. I was trying to guess why you wrote this series given that your cover letter doesn't provide a lot of benefits (other than dropping __HAVE_ARCH_*). > wonder why you make this a criteria at all. Because this is the main reason I would be willing to ack this series. This outweight the increase number of files with just a single function implemented. > The functions being one per > CU is such that they can be individually overridden by an arch, without > pulling in dead code. I would agree with functions like memcpy/memset() because you can gain a lot to outweight the implementation in assembly. I am not convinced this would be true for functions such as strlen(). So overall, the number of functions requiring overriding will likely be pretty limited and #ifdef would be IMHO tolerable. Although, I would be OK with creating a file per function that are already overrided. For all the others, I think this is just pointless. Cheers, -- Julien Grall