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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7216DC433FE for ; Wed, 26 Oct 2022 10:31:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233230AbiJZKb2 (ORCPT ); Wed, 26 Oct 2022 06:31:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35260 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231628AbiJZKb1 (ORCPT ); Wed, 26 Oct 2022 06:31:27 -0400 Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F9F489CF7 for ; Wed, 26 Oct 2022 03:31:26 -0700 (PDT) Received: by mail-pl1-x631.google.com with SMTP id g24so8604619plq.3 for ; Wed, 26 Oct 2022 03:31:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=o3WIGqmDVFhlGjUFlqXNdRIfQzvN1HtZiVx+H8leinM=; b=VfEtiLQslMh/3TkpwXoKybHiJzUCKs0GYdPqrpc9rfAYVuZeBBoEx8dj1i4f7rd5pj XCad0fbIQNZ4IO6B+NIzHRfZhMwSuNTV02S/LZynCEsdZJU0MvfL4ZOH+Qtvh+wfwaGP GS1rgiNS7dz+elSz3dKJYslAM4+q8Dcs3B2lk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=o3WIGqmDVFhlGjUFlqXNdRIfQzvN1HtZiVx+H8leinM=; b=li92nKwqS6PNp7Y7qqm58Owazt8pzsVPnlV3uVxuc214FhU7eColRoATLBNikHvWaV mTBqsB0489vSEr5owrl3hdDnhZCWQuVphFcRsq7qmNNppoDmPyAZuLFCcsB8czJxlOcH QGAHUaSWchfVfuaPKvlbW5K7WPL6DItUDnIJoZI+D4PKoK+/v0aoIJ6GJTkDAvvtyDk0 borPtpIoQQPfWxNJGI9MO1e8qw2GvfJHyzUxHh7h2BPc0KiyE+J5GGZ/dFO2MWGFpkZ8 q8tzubpqjqrfMaj+3OTef3J6wnlArgATAMlnhMe74A/gLNl77Tv2ApoQeSEqp2AVcD8v kYNQ== X-Gm-Message-State: ACrzQf2loJ1aOBuPhBhnLycihsIwrAWNDMjXewrr4BiowiOh1RbWjc5k wUHBi213S2jLToUuBdd/K4NmJw== X-Google-Smtp-Source: AMsMyM5cWloPs/ejDnpQuQqlrBqj3Pmyy7NLWKvLszO7kuTyCdAGjLO4p9oITmGdV++NxSSwGoc1nA== X-Received: by 2002:a17:902:c24d:b0:186:a2d6:9f7f with SMTP id 13-20020a170902c24d00b00186a2d69f7fmr16324990plg.131.1666780286094; Wed, 26 Oct 2022 03:31:26 -0700 (PDT) Received: from google.com ([240f:75:7537:3187:faf6:e503:6cac:3b53]) by smtp.gmail.com with ESMTPSA id j7-20020a17090276c700b0017f73caf588sm2584663plt.218.2022.10.26.03.31.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Oct 2022 03:31:25 -0700 (PDT) Date: Wed, 26 Oct 2022 19:31:21 +0900 From: Sergey Senozhatsky To: Andrew Morton Cc: mm-commits@vger.kernel.org, senozhatsky@chromium.org, ngupta@vflare.org, minchan@kernel.org, ubizjak@gmail.com Subject: Re: + zram-use-try_cmpxchg-in-update_used_max.patch added to mm-unstable branch Message-ID: References: <20221018205005.52F6CC433C1@smtp.kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221018205005.52F6CC433C1@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org On (22/10/18 13:50), Andrew Morton wrote: > Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in > update_used_max. x86 CMPXCHG instruction returns success in ZF flag, so > this change saves a compare after cmpxchg (and related move instruction in > front of cmpxchg). > > Also, reorder code a bit to remove additional compare and conditional jump > from the assembly code. Together, hese two changes save 15 bytes from the > function when compiled for x86_64. > > No functional change intended. > > Link: https://lkml.kernel.org/r/20221018145154.3699-1-ubizjak@gmail.com > Signed-off-by: Uros Bizjak > Cc: Minchan Kim > Cc: Nitin Gupta > Cc: Sergey Senozhatsky > Signed-off-by: Andrew Morton I totally missed that patch. Reviewed-by: Sergey Senozhatsky