From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pdx1-sub0-mail-fallback-a200.dreamhost.com (pop.dreamhost.com [64.90.62.162]) by sourceware.org (Postfix) with ESMTPS id AAACC3858C35 for ; Tue, 17 Oct 2023 15:59:38 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org AAACC3858C35 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=gotplt.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gotplt.org ARC-Filter: OpenARC Filter v1.0.0 sourceware.org AAACC3858C35 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=64.90.62.162 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1697558380; cv=none; b=H3iqnqktk9xJ+pb6QfFztBa+sq1FpGcYJOLg3A11HjopCfAWpDRUgs9A89M8HAeHAG0G2JFD0OxOZRAA0y/aRfHlZoI+RD9CP8g/gzKU+TH5vSu2ZrpeHlopC2o+1r21wV4k5S8x50FUR2RW6pdnzAB0iKeXoNPzH3sdwtEU7ZU= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1697558380; c=relaxed/simple; bh=h175hIOkR5xLA2x07jL1QEuq77cCMxRsr7bcC9kT95w=; h=DKIM-Signature:Message-ID:Date:MIME-Version:Subject:To:From; b=Ik/ip8VMrv2DidBoSMWTsr3NCDToX9/6LjJLp/oeE05vc3GPsbQpzhYlGGNDdoRGreJPU/FJLHIrbBMLILnHpJkYympu2oOxnrc+B7uHflmPrDPQNqxFl/5O3723ovE7K3nceZyIt6XaWRDcg7WgRPHszFhQ25rcv8YYBfnuTZM= ARC-Authentication-Results: i=1; server2.sourceware.org Received: from pdx1-sub0-mail-a202.dreamhost.com (pdx1-sub0-mail-a202.dreamhost.com [10.35.49.224]) by pdx1-sub0-mail-fallback-a200.dreamhost.com (Postfix) with ESMTP id 4S8zFL0gJdz4Dc; Tue, 17 Oct 2023 08:59:34 -0700 (PDT) Received: from [192.168.2.12] (bras-vprn-toroon4834w-lp130-02-142-113-138-136.dsl.bell.ca [142.113.138.136]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: siddhesh@gotplt.org) by pdx1-sub0-mail-a202.dreamhost.com (Postfix) with ESMTPSA id 4S8zCr0cywzHY; Tue, 17 Oct 2023 08:58:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gotplt.org; s=dreamhost; t=1697558296; bh=gl3tH0TxFo0LywjI3eO3BQ1K5babbc24hXeNoViwCTc=; h=Date:Subject:To:Cc:From:Content-Type:Content-Transfer-Encoding; b=TaKOmwlwcknkeEuL14b07+aa62mIIN2tAEDxQH+oBV1LpXpvGqZJlSfayqbL5BtRk rujfxqCeXfrQ4b0nZ1iTCkuZSsR+A0QqXJuIiDNLJK8Ed5I5XqLJKnbW04SOHuYgC6 PsyOlLD7uTJADQpgMsJtr4aFf2IDoaslni8cnrYxMhe7XjSrKa34+/aeqgejRK5W0U GurD0R970c8dljZ+66u9djrOfVXQlTGWALpL1x5ikU0v1I2+OZ87miWoCar4aSy/li UuTwotDx/F2A1M5p+3GBXr4otNMQEiLXQUylbQc1feLEW5SzvjHkJoBBrIaaZltHvh 1rZLObS8wv6ww== Message-ID: <0516e7f2-6622-234e-1741-23313a58a78e@gotplt.org> Date: Tue, 17 Oct 2023 11:58:15 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: RFC: system-wide default tunables Content-Language: en-US To: DJ Delorie Cc: adhemerval.zanella@linaro.org, libc-alpha@sourceware.org References: From: Siddhesh Poyarekar In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-3031.4 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,TXREP 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 2023-10-17 11:43, DJ Delorie wrote: > Siddhesh Poyarekar writes: >> Only stricter overrides to systemwide tunables should be allowed, e.g. >> going from enabled memory tagging to disabled memory tagging. For >> numeric values such as mmap_threshold, we may need to figure out on a >> case by case basis what constitutes "stricter". > > Encoding "stricter" in the cache file might be difficult. If we were to > include enforcement, I'd opt for "can't override" vs "can't override > unless stricter". > That check would have to live in the code rather than in the cache file and would end up being per-tunable. Maybe enhance the callback routine in tunable_initialize path to pass the systemwide default, allowing the subsystem where the tunable is initialized to decide whether the envvar override should stick or not. Sid