From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-x22f.google.com (mail-oi1-x22f.google.com [IPv6:2607:f8b0:4864:20::22f]) by sourceware.org (Postfix) with ESMTPS id 871813856967 for ; Thu, 11 May 2023 18:15:49 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 871813856967 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-oi1-x22f.google.com with SMTP id 5614622812f47-3944816b579so786073b6e.1 for ; Thu, 11 May 2023 11:15:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1683828949; x=1686420949; 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=GSUjRwPtxtQVP9vHCj+eO9p2hm2oZR3mncCjvN2I4tY=; b=fdMCtSE8bewE/arKtgeRIOPbkXwx4KWfRlAI2a946Zcqg9oqEjZ0ISDQVdqQAyXv0N COCOVShb5TBG10yFa64yjnrqNB3H3r8u8iYt2oD/4TsmYwC5VCIoYPGoHC/3S7C7Q4Bn Nt+oLXJB/sUlWcW1tkIZhwszoGIDDBJ50wq+EGaRN4gYcolvyn9nubqr4yZi1m8cf1Gn 5G+3KBce8GCUTVDfWTRLSchddVyi400hP2IUy7umH5HgRvBHZJqmueMzJj7ecS1o/Maj ZuldTkNHaNV3+k8btL5n5BvsB2c4oPLqKt3PQoK4tL2XnKi4tlvTB/FVrarwM3DX5u/8 zG1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1683828949; x=1686420949; 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=GSUjRwPtxtQVP9vHCj+eO9p2hm2oZR3mncCjvN2I4tY=; b=kfmRZ8srjI6nBnCtlZIapb7Rmh8tjXFCVwk17tlOKEKsY3nvAza2cGq5O95837ILUj qv3rUmIeH1a0TmmOcd8vk77EhNZW0mipJ77gkQrQrLMftjiTy6xFvdu6hekr+DNm6NJ/ YtjTXhNtul9UnZaKFcB9mN5ftu2t3ygVfqSjHY9GBGg7s7iQDLZSPjbJZC41oCbQViL4 bwIROQBWBrs7BDOdRUK7cTHG9NtGYZL7DaHJPSTiWu7/ppeaORhLbGS8rZtfbFMurN8Z NLoWF5dEJ78ApvsFJfREHqIbyjhxVCelRZedevSOgVGXWv8FfWfPxDGHwTWgzITcT4h9 A/fw== X-Gm-Message-State: AC+VfDxsMtQ/9YU+jJO8PXe2o+UPffu7wZWsz7kI4/As/vQa7LGdIi7O 0/P8vaOtI/AHc5Sald6nsPoIDtLI9l1QAvJF7zo= X-Google-Smtp-Source: ACHHUZ6rppecwS3jAX5TT37+328kzh6Q+GVKm1yJCptl9KKsMbsrOsuegwA/5OPs98YRLUjpERRtzYGWa3nmat+0jdY= X-Received: by 2002:a05:6808:1924:b0:394:68b3:2685 with SMTP id bf36-20020a056808192400b0039468b32685mr202548oib.22.1683828948861; Thu, 11 May 2023 11:15:48 -0700 (PDT) MIME-Version: 1.0 References: <20230509031020.3496291-1-goldstein.w.n@gmail.com> <87wn1h6fya.fsf@oldenburg.str.redhat.com> In-Reply-To: From: Noah Goldstein Date: Thu, 11 May 2023 13:15:37 -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=-3.3 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 11:01=E2=80=AFAM Noah Goldstein wrote: > > 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 sho= uld > only ever really happen if we failed to read cache info. What is the > surprise? florian? > > > Thanks, > > Florian > >