From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ej1-x62e.google.com (mail-ej1-x62e.google.com [IPv6:2a00:1450:4864:20::62e]) by sourceware.org (Postfix) with ESMTPS id 66DA73858D37 for ; Wed, 2 Mar 2022 00:16:18 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 66DA73858D37 Received: by mail-ej1-x62e.google.com with SMTP id bg10so314309ejb.4 for ; Tue, 01 Mar 2022 16:16:18 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=+7JDoo0Sd3+UPlEpysG3Od2YWvzjVBgsUK6DtL5pBgU=; b=MDx0NlljqPMNNg9hx94cS0AqDablvcyquBZ4d/jjqNTpj7yybaHpwWPs+WQWKzXESA 0AhQtiOyiyGZDJ+y4G8awZ68m+p60CbcoJiayOvjHMkyRErRDyWMdf2AKgm1Z43ESFSF AGxoVjOJBoRwnmjvvedwHbTNlwLYekx9oGLSer0HFZMiDoRxXWPc+SsGf1Iqm99vjCK8 AAq+AvBrFknUqupSic1+9t5QpNHMrsZR4Hn1bNu0hBVYCLYDq1JhHTfMhhAb0hERoGkr r00+cKBXa6tK6VUDfOGoQ9jyCweGM1qqRuQBHyUj4vhRb1BG6i6/3C5DbjVODn2WXlc1 ZpjQ== X-Gm-Message-State: AOAM530mObMjNyUMejiy+HEgb7VmQhPbpAzrNugH1/K5Ss7ZxTq5Apqf r1oimBuZS0+UvdYkxEpcpK3LJ8VlyK+6iaCGb8yG2g== X-Google-Smtp-Source: ABdhPJyeZmf05Vc0dYGIKHQgmS8l1EM8bOU22YdlNPhk7P7z0UImnsXMQIqa1Jw3b6ddXiH4S4D2Yl4hpKpNDIBOZUI= X-Received: by 2002:a17:907:10d7:b0:6cf:1163:90bc with SMTP id rv23-20020a17090710d700b006cf116390bcmr21431877ejb.664.1646180177126; Tue, 01 Mar 2022 16:16:17 -0800 (PST) MIME-Version: 1.0 References: <6349834d9ea31f579b04ba9215b6449ce13f008e.camel@mengyan1223.wang> <1bb8ab09556727917d07ec31683996bb7e493fa6.camel@mengyan1223.wang> <20220224201334.GQ614@gate.crashing.org> <37e3b73aba3fd6dd6c109d0a06680af3577c4b41.camel@mengyan1223.wang> <874k4nvye3.fsf@oldenburg.str.redhat.com> <313b0e6eca1846dd5e994fd4c9f5d77d000247a0.camel@mengyan1223.wang> <9623880f9cd3d097bb76440413eae16b94204cae.camel@mengyan1223.wang> In-Reply-To: From: Satish Vasudeva Date: Tue, 1 Mar 2022 16:16:29 -0800 Message-ID: Subject: Re: Libatomic 16B To: Xi Ruoyao Cc: Florian Weimer , Stefan Ring , Xi Ruoyao via Gcc-help X-Spam-Status: No, score=-1.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, HTML_MESSAGE, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: gcc-help@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-help mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 02 Mar 2022 00:16:22 -0000 Hi, Just a quick clarification. Looking back at the description in https://gcc.gnu.org/legacy-ml/gcc-patches/2017-01/msg02344.html It sounds like CAS based implementation is a problem for volatile atomic loads. Can any one please elaborate what is the issue with volatile atomic loads. I am trying to do risk analysis in our code. Thanks Satish On Fri, Feb 25, 2022 at 9:25 AM Satish Vasudeva < satish.vasudeva@cohesity.com> wrote: > That's a great answer. Thank you > > Have a nice weekend. > > On Fri, Feb 25, 2022 at 9:16 AM Xi Ruoyao wrote: > >> On Fri, 2022-02-25 at 09:05 -0800, Satish Vasudeva wrote: >> > Thanks for a quick action on this. >> > >> > I see that a patch has been posted. >> > >> > I am new to this, can you please clarify what is the build option for >> > new and older Intel CPUs? >> >> You don't need to add any build option if you'll use the posted patch. >> The patch uses ifunc (https://sourceware.org/glibc/wiki/GNU_IFUNC) >> feature. It means libatomic will automatically select a best variant of >> 16B atomic load applicable for the CPU when it's loaded at runtime. >> >> > > Opened as https://gcc.gnu.org/PR104688 >> -- >> Xi Ruoyao >> School of Aerospace Science and Technology, Xidian University >> >