From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by sourceware.org (Postfix) with ESMTPS id E7A543858D28 for ; Tue, 7 Dec 2021 14:16:33 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org E7A543858D28 Received: by mail-pj1-x1031.google.com with SMTP id j6-20020a17090a588600b001a78a5ce46aso2050414pji.0 for ; Tue, 07 Dec 2021 06:16:33 -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=4c8a17Nw5RAhX84IqyBbB1gMK+v8/ce0hje1+dyN+Sg=; b=jBNfA0DegLzN3gG5s/2N68u90GGUCtT3AKE+DMRbERNtEJadAJDRxWUV2Yizt3eC5N vMqRjiTfz3G6C0846G4On1vPk79lPygFFvw3cjmyif1tVfafgNwQdmL9LqLvKqEDA3S2 sLdaBn9cNLsnFRH+ygzjphz8cJLkb0hoyGyiqcwMGEDPkFB2fIC4yplqGHYAhHEolkJ+ 6dgqHN0MiLItIEwClupv8Eix8l3UHrvNK0LSAqedoG9uGUgoFSK4nKBctE34XHDZDuAu sA8YqYknC++gWK+pinUYSriICVnjx3J2MIMrMcjG5DQFmyQJXz6FAY8RCUpfoR6dUYTY uldA== X-Gm-Message-State: AOAM531qkSgQDI1nAm9oIP6Mbnr4vwmlMpV/X0ppVNF2aIAwhcZ9roZS 69cLFxnkD4M1sCBHItVpi9d45OkFzzCTxTSXv1c= X-Google-Smtp-Source: ABdhPJxFPVI5klruT9THxkA4vN9s7Jl2OJPJiP0ffQvsEY/5qHvXlyEkJNTfW9JnKOpwg1s42TKtde4UjkOTeVY93rg= X-Received: by 2002:a17:902:ced1:b0:141:e15d:49e0 with SMTP id d17-20020a170902ced100b00141e15d49e0mr51657117plg.27.1638886593047; Tue, 07 Dec 2021 06:16:33 -0800 (PST) MIME-Version: 1.0 References: <20211206032303.7159-1-hjl.tools@gmail.com> <3639bca9-e90d-d3ff-c758-d2d5c4c0a3d2@linux.intel.com> <87r1aoqzlz.fsf@oldenburg.str.redhat.com> In-Reply-To: <87r1aoqzlz.fsf@oldenburg.str.redhat.com> From: "H.J. Lu" Date: Tue, 7 Dec 2021 06:15:57 -0800 Message-ID: Subject: Re: [PATCH] x86: Don't set Prefer_No_AVX512 for processors with AVX512 and AVX-VNNI To: Florian Weimer Cc: "H.J. Lu via Libc-alpha" , Arjan van de Ven , Hongyu Wang , liuhongt , Thiago Macieira Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3022.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 07 Dec 2021 14:16:35 -0000 On Tue, Dec 7, 2021 at 6:05 AM Florian Weimer wrote: > > * H. J. Lu via Libc-alpha: > > > Hongtao, Hongyu, can you find a Rocket Lake to test? > > I've found a lab machine with an i7-11700 CPU. Is there something I > could test for you? You can enable AVX512 in glibc with: $ export GLIBC_TUNABLES=glibc.cpu.hwcaps=-Prefer_No_AVX512 While bootstrapping GCC with -j8, track CPU frequency with turbostat. If there is no CPU frequency drop and build time is less comparing against without GLIBC_TUNABLES, we can enable AVX512. > (This could be non-production silicon, though.) > The frequency behavior of non-production silicon can be different. -- H.J.