From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B9E731EA7C2 for ; Thu, 15 May 2025 02:17:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747275477; cv=none; b=iZHN0xsRQOA5SxsGzwzuENB2+yCOWN1my7CL0ZGoBxVm8pnBGDca0ClH099WP5ZWgNinSLRXjY3K9tUNfXlfTWMOVWDoKDuj9KYcxTSiKZSHw0Rv5EBC02j2DJRXbclc6USYglZIYuq0a+qYL3CvM6Xh9FQ2DtgtHtBxRndR0lo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747275477; c=relaxed/simple; bh=tfw8zsMwGXtaSny6fvX/ec13kqYkzMfWrjcWnFJUdDg=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=K38lHcDzn37oPv9Zs6Tag2ie9dOKtEoAR1m1rnlOJucXAxsMqHb66Mm79POxDS7LWoF/Qahf6oTeqC05XKlSmzbz5OMjWICX3fcSmLyHNb3MVPXj5y1jzvkgmVvX+KgtBI4PVbFDa/KP+4wRWvQ4IToGRarGzLdVDP5uZ5ZWcAo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=UuIUN/nN; arc=none smtp.client-ip=192.198.163.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="UuIUN/nN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1747275476; x=1778811476; h=from:to:subject:date:message-id:in-reply-to:references: mime-version:content-transfer-encoding; bh=tfw8zsMwGXtaSny6fvX/ec13kqYkzMfWrjcWnFJUdDg=; b=UuIUN/nNKUrvfJ+z0sNUA1kO2/rbp3ZFZ8Rpq6iXaSHpRLae9rHAZ8dz XNirTm44GmSarjD5r6X1v/eMbXWyE6MprBQJegwne0E+x+Kmm/9qsh6As a/FYLQIacTGS7NQ8kKRHUjjVMu+FHlyc5DWZtY6vGUZWAZRu4MgkCH+Ln WIQXw/qAiBCyBwD+aJAVpn75bVMMo7/Y8wxw7UqNC5EsqIwbGZVggkPQ/ 3waN8yeuzUyX2h/J798mVtQP7xqb1sfCA1eDxJku4TsqTVjmrTmFKQsCb 8pVuqX/EFw5WQFI7y0Hz6ZjbnBAVZ5JwLKKtDmXvBZOMiwZusTH8oHmKY A==; X-CSE-ConnectionGUID: Jsh+miYMQQyyMyAJG+l+7w== X-CSE-MsgGUID: UzCEV6L1RF6r+8yViqiOjg== X-IronPort-AV: E=McAfee;i="6700,10204,11433"; a="66749936" X-IronPort-AV: E=Sophos;i="6.15,289,1739865600"; d="scan'208";a="66749936" Received: from fmviesa010.fm.intel.com ([10.60.135.150]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 May 2025 19:17:53 -0700 X-CSE-ConnectionGUID: i8eCsDggQS+ZqOQcxqMVLg== X-CSE-MsgGUID: c1eLZHsUTKmIMuiMNQ1lHQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,289,1739865600"; d="scan'208";a="138724650" Received: from unknown (HELO hyperion.jf.intel.com) ([10.243.61.29]) by fmviesa010-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 May 2025 19:17:49 -0700 From: marc.herbert@linux.intel.com To: linux-cxl@vger.kernel.org, nvdimm@lists.linux.dev, alison.schofield@intel.com Subject: Date: Thu, 15 May 2025 02:14:44 +0000 Message-ID: <20250515021730.1201996-1-marc.herbert@linux.intel.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Major changes in v2: - The old $SECONDS variable is dropped from journalctl. Which allows: - ... dropping the very short-lived COOLDOWN proposed in version 1. - A new, optional NDTEST_LOG_DBG code which allows "stress testing" the approach and proving that it is safe. I tested and compared for many hours $SECONDS versus the NDTEST_START approach that Alison submitted a few months ago and the conclusion is very clear: - $SECONDS does require a ~1.2 cool down between every test. As it was done in v1. - NDTEST_START requires zero cool down. So that is why I dropped $SECONDS and the cool down. > Split them into a patchset for easier review and then I'll take a > look. Thanks! There are 3 logical changes in the main commit: A1) Dropping $SECONDS, replaced with NDTEST_START A2) The new NDTEST_LOG_DBG which was/is critical for: - proving that $SECONDS required a "cool down" (with version 1) - proving NDTEST_START does _not_ require any cool down, safe even without any. B) The new, _harden_ journalctl check in check_dmesg() and its kmsg_fail_if_missing and kmsg_no_fail_on. The main feature! - B) requires A1) because $SECONDS is too imprecise. With B) only, the tests fail. - The A2) test code achieves nothing without B), it cannot prove anything without B). - A1) and A2) are logically independent but their code are fairly intertwined and very painful to separate. Plus, B) would have to sit in the middle: A1->B->A2 Long story short: - while they could be logically separate, these changes are tightly coupled with each other. - breaking down that (relatively small) commit is theoretically possible but would be very labor intensive. I know because I just went through a similar "git action" to compare $SECONDS versus NDTEST_START for COOLDOWN reasons and it was not fun at all.