From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 7F28C20248 for ; Fri, 15 Mar 2019 15:13:47 +0000 (UTC) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:references:date:in-reply-to :message-id:mime-version:content-type; q=dns; s=default; b=tCyyJ +EQePKZ7cTfqFAvhuPRtXFlOTLBsfo//dA4fzZCqj7qBrDAP214dZRzzxwZEU1qn nfTs7Aqsyr+9rTb4BtJKRFXqzz8Bw0dK2f3rZqiPSZE/SWrYn+mB44RLNevL8OkD yCAuG1DxchLww2GF9yoggHcV5AiJHoAJVDQ0FA= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:references:date:in-reply-to :message-id:mime-version:content-type; s=default; bh=/rehHkBka52 UvdL8K2kulRLli8s=; b=Q54RdnUhraRxF/DZUb5hbePQ5djbn5cGeEuJPeDtS9X aKImpJ+xoLR/YHfS6IMpgZtWa+VAfQdfKwjn3zZoFNXXmABbpshoSrVGknyBHEEH pICdUEbzkC19Mz909X6RAKGtiks/w0bwY9hQsh+IcfkzdYPCfbMlknd6CDdHcVFY = Received: (qmail 68417 invoked by alias); 15 Mar 2019 15:13:33 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 68398 invoked by uid 89); 15 Mar 2019 15:13:33 -0000 Authentication-Results: sourceware.org; auth=none X-HELO: albireo.enyo.de From: Florian Weimer To: Yann Droneaud Cc: Paul Eggert , libc-alpha@sourceware.org Subject: Re: [PATCH] Fix multiple minor tzset glitches [BZ #24004] References: <20190211163728.31655-1-eggert@cs.ucla.edu> <87h8d1e8tk.fsf@oldenburg2.str.redhat.com> <9f3882f6-e056-95d1-4506-58fd87cbf6c2@cs.ucla.edu> <87d0muesi3.fsf@oldenburg2.str.redhat.com> <4d46da6e-6901-f736-f573-3dfbef27a3df@cs.ucla.edu> <87d0mt5yxa.fsf@oldenburg2.str.redhat.com> <877ed1uwal.fsf@oldenburg2.str.redhat.com> <683f2a6c6a5cb4543545ff1253fa67ceee1deec7.camel@opteya.com> Date: Fri, 15 Mar 2019 16:05:05 +0100 In-Reply-To: <683f2a6c6a5cb4543545ff1253fa67ceee1deec7.camel@opteya.com> (Yann Droneaud's message of "Fri, 15 Mar 2019 14:12:56 +0100") Message-ID: <87ef78faam.fsf@mid.deneb.enyo.de> MIME-Version: 1.0 Content-Type: text/plain * Yann Droneaud: >> With the mapped file, there is no file polling as such, just a few >> memory loads. The cost is that the system administrator needs to run a >> command after updating any of the covered configuration files, which is >> why this has to be optional (and opt-in per configuration file). There >> probably aren't that many configuration files where this is needed. > > I think there's a caveat with memory mapped file: if a new version of > the configuration file is created and renamed to the configuration > location, replacing the previous one, applications won't notice the > update, as the memory mapping will still reference the previous file. Sure, but the configuration compiler can write a flag to the old mapping that indicates it is out of date. Checking that flag has to be part of the sequence that verifies if polling is required. I believe nscd does something similar when it invalidates a mapping.