From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa1-x35.google.com (mail-oa1-x35.google.com [IPv6:2001:4860:4864:20::35]) by sourceware.org (Postfix) with ESMTPS id 2E2A63854142 for ; Tue, 9 May 2023 16:01:55 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 2E2A63854142 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-oa1-x35.google.com with SMTP id 586e51a60fabf-195ee1be41aso2624098fac.1 for ; Tue, 09 May 2023 09:01:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1683648114; x=1686240114; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=Az0u9OcTawQsCQTOQtv1MOnWsDhMwiIcr4FA2V8XRcQ=; b=FNYK9LXKeQeKbwt4jMbab011O2syS7TLdG9ZnAXBF+WHJMG5eA+1ko5zBhpywOd3uK HIko9HVLvj4ZkIcuplnfiZu8zmhf9T2xQHhzYEnVssHKjVYU1w2mwjeWcQl5XBSfYWUc 31Vx8t9QhHs9Ji+sY4gUs/iIBMi364/uE0f9kCLoBLMN1ZbgHwBnUyasukiSTLcDDhNQ ehT53qpiarSQ9Vr2tG5sVAYOX7lQ7RsCqEsCumuAEYnnfMoMNUIhgbZ639MNf5DYpsXI 8uurk8uHbA4of5ZBVsN0Vl8JL1OPnmxSbHC22fVIuvYYr6TWxKkfBGxNAP+2mzgVBkoU WOFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1683648114; x=1686240114; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Az0u9OcTawQsCQTOQtv1MOnWsDhMwiIcr4FA2V8XRcQ=; b=fYYGmrMY46W6AmAJFJLtPC14FFSopRmfS/qej5ARRGuy+dwqi4dhFp+UtwwJZzkQWJ vO3mGKftrXmR5Fs5JaVlV1yq5GMYP0pxb5WzAcw2juT1wPZO1d6q6S0WUhjW2WGLJk99 cyyIpJHl9kT2K2cS7p+8c8ZWmM78ld6TvYHqjy87697gOAmaumA+wqpSUO/89DpINZEb MhF28E3v/bBg2cKt4rXlWPhEeaWYjCt09k6G2vnR7CcMOXIGZWmlJtYBlTw0J/pBFa4I 43sfvzsDuDiX1POsWj5hhPcBrqoXVPM/oBVSfExwvxCbcFQEhy2WKYeN/rs505Y57Mye G0WA== X-Gm-Message-State: AC+VfDweYVb4th6YoU/+ctiiUAGgIcw2klNcOUEryDabgMsyGY/du5tx A16bGDZ00GEZoxSFsonHC/QSJL/5Z3kTVfyv8EA= X-Google-Smtp-Source: ACHHUZ4bSNnzNJhKm1fbrN+hTIeke6D+FeuPzOcBOINQDCWQ1rA+10eegReYTgpdEHnV176cW9xkYIhtfLqCx5tPCRY= X-Received: by 2002:a05:6870:44d6:b0:172:7fc0:9188 with SMTP id t22-20020a05687044d600b001727fc09188mr6707729oai.35.1683648114213; Tue, 09 May 2023 09:01:54 -0700 (PDT) MIME-Version: 1.0 References: <20230509031020.3496291-1-goldstein.w.n@gmail.com> <87wn1h6fya.fsf@oldenburg.str.redhat.com> In-Reply-To: <87wn1h6fya.fsf@oldenburg.str.redhat.com> From: Noah Goldstein Date: Tue, 9 May 2023 11:01:42 -0500 Message-ID: Subject: Re: [PATCH v1] x86: Use 64MB as nt-store threshold if no cacheinfo [BZ #30429] To: Florian Weimer Cc: Noah Goldstein via Libc-alpha , hjl.tools@gmail.com, carlos@systemhalted.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-3.1 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,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Tue, May 9, 2023 at 3:56=E2=80=AFAM Florian Weimer = wrote: > > * Noah Goldstein via Libc-alpha: > > > If `non_temporal_threshold` is below `minimum_non_temporal_threshold`, > > it almost certainly means we failed to read the systems cache info. > > > > In this case, rather than defaulting the minimum correct value, we > > should default to a value that gets at least reasonable > > performance. 64MB is chosen conservatively to be at the very high > > end. This should never cause non-temporal stores when, if we had read > > cache info, we wouldn't have otherwise. > > I think that's quite surprising for GLIBC_TUNABLES. Maybe that logic > should only activate if the default was set from cache sizes? > I don't quite understand what you mean by "only active if the default was set from cache sizes"? This logic only triggers if total_cachesize / 8 < ~16kb. I think this shoul= d only ever really happen if we failed to read cache info. What is the surprise? > Thanks, > Florian >