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=-5.0 required=3.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 05896C43215 for ; Mon, 2 Dec 2019 09:25:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB0B520833 for ; Mon, 2 Dec 2019 09:25:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727428AbfLBJZk (ORCPT ); Mon, 2 Dec 2019 04:25:40 -0500 Received: from ns.iliad.fr ([212.27.33.1]:58668 "EHLO ns.iliad.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726254AbfLBJZk (ORCPT ); Mon, 2 Dec 2019 04:25:40 -0500 Received: from ns.iliad.fr (localhost [127.0.0.1]) by ns.iliad.fr (Postfix) with ESMTP id 907632041C; Mon, 2 Dec 2019 10:25:37 +0100 (CET) Received: from [192.168.108.51] (freebox.vlq16.iliad.fr [213.36.7.13]) by ns.iliad.fr (Postfix) with ESMTP id 7DB261FFCE; Mon, 2 Dec 2019 10:25:37 +0100 (CET) Subject: Re: [PATCH v1] clk: Convert managed get functions to devm_add_action API To: Dmitry Torokhov , Bjorn Andersson Cc: linux-clk , Linux ARM , LKML , Stephen Boyd , Michael Turquette , Kuninori Morimoto , Russell King , Sudip Mukherjee , Guenter Roeck References: <3d8a58bf-0814-1ec1-038a-10a20b9646ad@free.fr> <20191128185630.GK82109@yoga> <20191202014237.GR248138@dtor-ws> From: Marc Gonzalez Message-ID: Date: Mon, 2 Dec 2019 10:25:37 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: <20191202014237.GR248138@dtor-ws> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV using ClamSMTP ; ns.iliad.fr ; Mon Dec 2 10:25:37 2019 +0100 (CET) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/12/2019 02:42, Dmitry Torokhov wrote: > On Thu, Nov 28, 2019 at 10:56:30AM -0800, Bjorn Andersson wrote: > >> On Tue 26 Nov 08:13 PST 2019, Marc Gonzalez wrote: >> >>> Date: Tue, 26 Nov 2019 13:56:53 +0100 >>> >>> Using devm_add_action_or_reset() produces simpler code and smaller >>> object size: >>> >>> 1 file changed, 16 insertions(+), 46 deletions(-) >>> >>> text data bss dec hex filename >>> - 1797 80 0 1877 755 drivers/clk/clk-devres.o >>> + 1499 56 0 1555 613 drivers/clk/clk-devres.o >>> >>> Signed-off-by: Marc Gonzalez >> >> Looks neat >> >> Reviewed-by: Bjorn Andersson > > This however increases the runtime costs as each custom action cost us > an extra pointer. Given that in a system we likely have many clocks > managed by devres, I am not sure that this code savings is actually > gives us overall win. It might still, I just want to understand how we > are allocating/packing devres structures. I'm not 100% sure what you are saying. Are you arguing that the proposed patch increases the run-time cost of devm_clk_put() so much that the listed improvements (simpler source code, smaller object size) are not worth it? AFAIU, the release action is only called - explicitly, when devm_clk_put() is called - implicitly, when the device is removed How often are clocks removed? In hot code-path (called hundreds of times per second) it makes sense to write more complex code, to shave a few cycles every iteration. But in cold code-path, I think it's better to write short/simple code. Regards.