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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 77FB8EE01E0 for ; Wed, 13 Sep 2023 16:56:47 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qgT9n-0000ib-6l; Wed, 13 Sep 2023 12:56:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qgT9m-0000hX-AP for qemu-devel@nongnu.org; Wed, 13 Sep 2023 12:56:02 -0400 Received: from mail-pl1-x634.google.com ([2607:f8b0:4864:20::634]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qgT9j-0004OK-J5 for qemu-devel@nongnu.org; Wed, 13 Sep 2023 12:56:02 -0400 Received: by mail-pl1-x634.google.com with SMTP id d9443c01a7336-1c0ecb9a075so52917025ad.2 for ; Wed, 13 Sep 2023 09:55:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1694624158; x=1695228958; darn=nongnu.org; h=content-transfer-encoding:in-reply-to:from:references:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=1KRCjUOxyzReqnQBZmjiPDgFqMCswZgDzYqJUA6afw8=; b=l+dlCtlD7Gvt594sBp6d82bnhNJjCgLRi5LDfEQaVl7FLyDuOWeCFShUsxP3o0a2zZ RjTD0uWu60YL+Xb9MrLQfS4ZFPr/yCcmP4A7qCmBuruIHAmUv9841l2yR71qXxlN2rJ7 ms1FFBOauIn4Q7EwYX8fOA6pJiGlUWprK3zylpIZvgP3vx3T+G7KqCcXsSX2FlsiKHnR xGjAxh8y47DD1HtPWTBUhaVdpN/fTp9pHGIwd0IK+n7nN+CV4aI2evTdombooMErMbv0 TqzzNAkNZpaoAzlQcW4FD3Apy2qMaTbAEySFB7S8xqLC03e4TyuSSZFkCEhst7gNm3x4 ymyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694624158; x=1695228958; h=content-transfer-encoding:in-reply-to:from:references:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1KRCjUOxyzReqnQBZmjiPDgFqMCswZgDzYqJUA6afw8=; b=qqs4lO5bGdnS7w17vxUnkFbf2DSPWmdZ1dNS1lIsslFWlppIvEMIjBpfjj+LSGVrvQ 0QcmPkP/tk+yPcNiBeI1XJmY+zzVxKbo4W/4Loq9sxj3wTeGRTbG8Kc/yrTyju2rD0l8 kUB7dbI8JkuVsXJ8SKl4PZ0XpTJePQMF1MEGdu9QoY7jQ+8ab/MPgvEeLLv1qIb7YzFH MCzwx93fDtsMxTkLkCzPeZ4Pcrb3fjywKUpfSZxnIRkylCFyIxmoJ9fd4XZigv1vdpiO DfshTUTtQketytqenNLgcdbdwwsFfHvriFkI4OFfg96YWYm4ZgQTTZ9ioIKOFt0YGWwQ YlGQ== X-Gm-Message-State: AOJu0YwrpDwEgTu8oozSwQQZ/3iXh4fEap/KpKvZPca1PuGPxr/CVE4B iPPXwPfpSTXHdtki8byVs7LhVQ== X-Google-Smtp-Source: AGHT+IGBYHqSCZPgWpS6wHaIx5pxkJRlA41vhQUH+7gk8e8rzcSW2rOLBa3ldnhd0tcPP34afntM+w== X-Received: by 2002:a17:902:c244:b0:1c3:94a4:34bd with SMTP id 4-20020a170902c24400b001c394a434bdmr3327556plg.40.1694624157654; Wed, 13 Sep 2023 09:55:57 -0700 (PDT) Received: from [192.168.0.4] ([71.212.131.115]) by smtp.gmail.com with ESMTPSA id p12-20020a170902a40c00b001b891259eddsm10637946plq.197.2023.09.13.09.55.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Sep 2023 09:55:57 -0700 (PDT) Message-ID: Date: Wed, 13 Sep 2023 09:55:55 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.0 Subject: Re: [PATCH] target/hppa: Optimize ldcw/ldcd instruction translation Content-Language: en-US To: Helge Deller , qemu-devel@nongnu.org, =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= References: From: Richard Henderson In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::634; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x634.google.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-1.473, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 9/13/23 07:47, Helge Deller wrote: > + haddr = (uint32_t *)((uintptr_t)vaddr); > + old = *haddr; This is horribly incorrect, both for user-only and system mode. > + /* if already zero, do not write 0 again to reduce memory presssure */ > + if (old == 0) { > + return 0; > + } > + old = qatomic_xchg(haddr, (uint32_t) 0); You're also dropping the required host memory barrier. Frankly, the current tcg_gen_atomic_xchg_reg is as optimized as you'll be able to do. I really doubt the "avoid write 0" is measurable at all. r~