From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.alien8.de (mail.alien8.de [65.109.113.108]) (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 779681E51E; Fri, 26 Jan 2024 18:57:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=65.109.113.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706295436; cv=none; b=UPeBlPPMgzrOqEVCoGqyrUmCLNVyRgbjYAkJIAxmriBF00hzgIq0k0ZnYCKmYov0lUEGc5ooeyI8hu1lfIAPVy3fLrxf3tFJsZmbXQSNWWY0M0gOz7fXk3uJvm5prl6bjPo9+P4TZNSKm7TsFH/2uvZT/JQCb7Rpjuu49DjtvEM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706295436; c=relaxed/simple; bh=QJe1FJ1iBaalO5uoFk0dCsivP88lPhMfWnHVPQV7TEg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=V6KKfJzSR3aD5UmZRmz5Ur+FOiAxAk0SJ7NB33z8vCwgc++05ou+BK4W9nzpws7WTGPJ5k9DQm9XJUwAOMTP1bkUdIrqtOXFOrQd66nYZ7Tt1pvPqwue57VtbmSZ/lSzvPburKAubyfD4k86CCV0NJ2Lpn+fGomTlRMupFStnkQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de; spf=pass smtp.mailfrom=alien8.de; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b=Gk6qPLPc; arc=none smtp.client-ip=65.109.113.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alien8.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b="Gk6qPLPc" Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id 79D1240E016C; Fri, 26 Jan 2024 18:57:05 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Authentication-Results: mail.alien8.de (amavisd-new); dkim=pass (4096-bit key) header.d=alien8.de Received: from mail.alien8.de ([127.0.0.1]) by localhost (mail.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 5WLNMonkyGe7; Fri, 26 Jan 2024 18:57:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=alien8; t=1706295423; bh=xhhU0pI4cvWOVs/8fChYblqpo/BatkU5qzvZCo8PM24=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Gk6qPLPcz3QyHGb+YZrdeyar1yu/82X4/OlpJjJe/3pC3U1xpXztdO1fqU3mosVLv UlsfzXIVa55o6ZrUHl5/auceFNgMAzyq7VJiNGjV7opMRfbyum2pVY7dGgHDZjxZbr dYJq7D+T2rgLX6KsRaYGsDn23zcIXobLBMTQWhQXlMkJ1r+D6zZ7bRMEgu+tCyDjx0 XUYp/QMRJ/2x29ucUkKlG5uVKjCyBow1ySc6rHRNfGWE7/qXB2A8vA4a9wbkDgs5kK 7qHrYLRdyf/vF8e55qq27+E4zJzFin7H2ZCqCVL+f8Ht/xx1VJCrDaWKvBaA/c/Eku J7izqRGN2k8vZ36o4hGuubBn4h04D4h68ZHx4wSc1A+5ODc0YSPjL+11qXVUK0i/Ie NshSqXqMHaOSAUWnETUBy+dvVeatGrvtlsOmLdXfcLFIFn+psEC2LzzIDEeGano4gD qTUjJi0C+3YBjLqqDwRnAqUxGhkYys5dO4hm42c2dxIUjFhClEp3bCMhAor5nv7hy5 S8rXEnukgKW6CmkvaoLDq6YvPpPwsK/r+vdpnt76JfrGjqXlNebks1B3wzs0t3GUYi 69hulmUU0AXfVHHBlckzj+BBhEXYwVTVQYSlEDkjI8O9oeeFOFv9E0gHnGJ7TM7W3h /byjo3FsQMKAO3RyWAMVTD/8= Received: from zn.tnic (pd953033e.dip0.t-ipconnect.de [217.83.3.62]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 3E04340E0196; Fri, 26 Jan 2024 18:56:54 +0000 (UTC) Date: Fri, 26 Jan 2024 19:56:49 +0100 From: Borislav Petkov To: "Luck, Tony" Cc: Avadhut Naik , "linux-trace-kernel@vger.kernel.org" , "linux-edac@vger.kernel.org" , "rostedt@goodmis.org" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "yazen.ghannam@amd.com" , "avadnaik@amd.com" Subject: Re: [PATCH v2 0/2] Update mce_record tracepoint Message-ID: <20240126185649.GFZbQAccZphdW_0CkH@fat_crate.local> References: <20240125184857.851355-1-avadhut.naik@amd.com> <20240125185821.GDZbKvTW93APAiY1LP@fat_crate.local> <20240126102721.GCZbOJCTqTVmvgOEuM@fat_crate.local> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Fri, Jan 26, 2024 at 05:10:20PM +0000, Luck, Tony wrote: > 12 extra bytes divided by (say) 64GB (a very small server these days, may laptop has that much) > = 0.00000001746% > > We will need 57000 changes like this one before we get to 0.001% :-) You're forgetting that those 12 bytes repeat per MCE tracepoint logged. And there's other code which adds more 0.01% here and there, well, because we can. > But the key there is keeping the details of the source machine attached to > the error record. My first contact with machine check debugging is always > just the raw error record (from mcelog, rasdaemon, or console log). Yes, that is somewhat sensible reason to have the PPIN together with the MCE record. > Knowing which microcode version was loaded on a core *at the time of > the error* is critical. So is the rest of the debug info you're going to need from that machine. And yet we're not adding that to the tracepoint. > You've spent enough time with Ashok and Thomas tweaking the Linux > microcode driver to know that going back to the machine the next day > to ask about microcode version has a bunch of ways to get a wrong > answer. Huh, what does that have to do with this? IIUC, if someone changes something on the system, whether that is updating microcode or swapping a harddrive or swapping memory or whatever, that invalidates the errors reported, pretty much. You can't put it all in the trace record, you just can't. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette