From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A081FC433DF for ; Tue, 16 Jun 2020 16:37:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74A8A208B3 for ; Tue, 16 Jun 2020 16:37:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KxXudJv/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729289AbgFPQhq (ORCPT ); Tue, 16 Jun 2020 12:37:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728860AbgFPQho (ORCPT ); Tue, 16 Jun 2020 12:37:44 -0400 Received: from mail-ot1-x344.google.com (mail-ot1-x344.google.com [IPv6:2607:f8b0:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55E20C061573 for ; Tue, 16 Jun 2020 09:37:44 -0700 (PDT) Received: by mail-ot1-x344.google.com with SMTP id d4so2037781otk.2 for ; Tue, 16 Jun 2020 09:37:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:reply-to:mime-version :content-disposition:user-agent; bh=TE/ZKWyB2620TP2EStc7D0hpU9orgSRap32pD2tzkHA=; b=KxXudJv/oNfqh/xAZsh+IWTtda1LPW3x4Y6CV2p6pCnOWAGf6Gui0vR0G+5T8eqjFp TxXhkHSmNl/MW9pamMii/v57kxZ1lUvkhEJ+m/rlgtjzbew8eTmMA+0s4wGC76YZqGyA ZsnefV2t7mrSBpOaSU1a4OAm45v3IsYr2ChHivKaqKV96cioQ3jPpGOZsotthZDWbIF3 g+dqtpoQGjvobZM9D2dicx+3tohp9Bkb6FesK8rhtiZxgkHYl6UdpP3xkuzhB0joo88i Y6a9Y39M9G6sBSBzJ9Q2/pqb3vUz5IAcf649+HMvoRw4VI03uWOb9rUeV/M5gM5alAXi aQog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :reply-to:mime-version:content-disposition:user-agent; bh=TE/ZKWyB2620TP2EStc7D0hpU9orgSRap32pD2tzkHA=; b=LlTXubLgK6ypxfAnyMGREi1HwsIoZK70R2WzY3mdhPHpSexAFDsB2IQw4pi6Una6yS tHW0lIDPmYkv9BVhx7Mg6xBWO8HEaOdQCREnyKnsJWnRq5DdqhPCz8ZixchnZ0Mz6A4g UJWfiYZMssrIa9ozARnhuiC6om6AfluJlFXTjWVk8awRNWBt+nFbv1T+9st1ST7/qm0S ZVS1Yeh6sjPXMBB2D6024KaZJ+eM5crcC/fo8e33jop5l3BxPhcTxBzLtGSxaMBFDWLe G/YRigvgmJT23/g+1L9QJEaVHBqg6AfZECbm3b6N6Jgbuaaq6KbTiqfzKgBqxP+UvWMK eCQg== X-Gm-Message-State: AOAM532VciJi68XpbiWpbTaByRZ35sgc5iZxNvXZhyce2Z5g+/4tSg8T 83DgCTqJOzEeCZ/cJoPfgw== X-Google-Smtp-Source: ABdhPJwTDwGop6YHLh+8FJsGMCWNnVfiMMG3DuZdcfQj4N2/e7jLsRlPwcBbucT61GfZsJSBl9M6hQ== X-Received: by 2002:a05:6830:120f:: with SMTP id r15mr2994107otp.348.1592325463561; Tue, 16 Jun 2020 09:37:43 -0700 (PDT) Received: from serve.minyard.net (serve.minyard.net. [2001:470:b8f6:1b::1]) by smtp.gmail.com with ESMTPSA id 94sm4137736otb.47.2020.06.16.09.37.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Jun 2020 09:37:42 -0700 (PDT) Received: from minyard.net (unknown [192.168.27.193]) by serve.minyard.net (Postfix) with ESMTPSA id E46E4180050; Tue, 16 Jun 2020 16:37:41 +0000 (UTC) Date: Tue, 16 Jun 2020 11:37:40 -0500 From: Corey Minyard To: linux-watchdog@vger.kernel.org, Wim Van Sebroeck , Guenter Roeck Cc: Gabriele Paoloni Subject: Millisecond level watchdog interface Message-ID: <20200616163740.GF3090@minyard.net> Reply-To: minyard@acm.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org Hi, I'm representing the Elisa group, an organization working on making it easier to use Linux in safety critical applications. As part of this, one thing we need is a watchdog that has a much finer granularity than one second. In some applications, that is just too long. Would the watchdog maintainers be ameniable to changes to the interface to support finer granularity? Milliseconds should be fine, though higher resolution would be fine, too. If so, there are a number of ways you can implement this. You could make the interface modal, meaning that you "throw a switch" and the standard interfaces become millisecond-level. Or you could create new ioctls with millisecond level granularity. You would probably want some way to fetch the granularity of the timer, too. Maybe there's another better way. Thanks, -corey