From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 627093A9851 for ; Thu, 14 May 2026 07:53:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778745218; cv=none; b=N3bDNlD+K6gjn5mCbuJBeYtA5dMSDrL94mAtp0iq6MGu7ZW0kAH2jm6ygIX+vzXfC8QIo1q9/T/xx+jH5K/6IJEz7/Sp5U5utYUIVJFf+E1bJmN4wSfqSpnRXhvr+hL2aVzn0/LUQ3WTAujIFL4O95PdAd212+qJvLM22gpOfnI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778745218; c=relaxed/simple; bh=dqHAiy8N4GKusiFmjSXYFO5zN6/xIzrnuFVNwBX1oFw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=o1GC9lUyUAIH9l1eaRirwrLs7qVDPhEK5wypJI/vvGFzt8vsP2Ji4UBb44IWc5q/Ks7QaAPTqTCf5lwFZOj6QPaQf9kXjLGJC2XZEPVlThCrtD0f9NrA9MBi9v8gWDeOMgGyfDqqlD8+l6FR90Rjn6F8D+RvjKts+YRofa2FMlY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de; spf=pass smtp.mailfrom=suse.de; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=NLobmCHR; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=A9w6PMis; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=NLobmCHR; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=A9w6PMis; arc=none smtp.client-ip=195.135.223.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="NLobmCHR"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="A9w6PMis"; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="NLobmCHR"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="A9w6PMis" Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id C7E2C5DA1D; Thu, 14 May 2026 07:53:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1778745215; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=U1ZRMTI8Ywd13megUVyotbWjue2n81p1QBp0eWqva3U=; b=NLobmCHRcXW6IChPw0zbCwTXQBdtblx5PSitCp6/XZhSPtAOTE0Ado231tFn0hefLYiCtG 3KOUt4XP3YXDQ9N6kkOyZM+bjKkrV+k424X80ByFBY248qN+RUnDJBW7Gwrx556OfNqozG DfkOl6xLitXPav76LNTHszIQur8ZVCc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1778745215; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=U1ZRMTI8Ywd13megUVyotbWjue2n81p1QBp0eWqva3U=; b=A9w6PMisWL7GFM0mrtAV5oXtt/4JjidQsIbHnX+euHGAdwM0YARFovS0c7KPoB0MgnOGx/ oLS3T3+2thtO7YCA== Authentication-Results: smtp-out1.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1778745215; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=U1ZRMTI8Ywd13megUVyotbWjue2n81p1QBp0eWqva3U=; b=NLobmCHRcXW6IChPw0zbCwTXQBdtblx5PSitCp6/XZhSPtAOTE0Ado231tFn0hefLYiCtG 3KOUt4XP3YXDQ9N6kkOyZM+bjKkrV+k424X80ByFBY248qN+RUnDJBW7Gwrx556OfNqozG DfkOl6xLitXPav76LNTHszIQur8ZVCc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1778745215; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=U1ZRMTI8Ywd13megUVyotbWjue2n81p1QBp0eWqva3U=; b=A9w6PMisWL7GFM0mrtAV5oXtt/4JjidQsIbHnX+euHGAdwM0YARFovS0c7KPoB0MgnOGx/ oLS3T3+2thtO7YCA== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id B42FD593A9; Thu, 14 May 2026 07:53:35 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id etR1K39/BWqqBwAAD6G6ig (envelope-from ); Thu, 14 May 2026 07:53:35 +0000 Received: by incl.suse.cz (Postfix, from userid 1000) id 67A8310719A; Thu, 14 May 2026 09:53:31 +0200 (CEST) Date: Thu, 14 May 2026 09:53:31 +0200 From: Jiri Wiesner To: Dimitri Sivanich Cc: Linux Kernel Mailing List , Steve Wahl , Justin Ernst , Kyle Meyer , Russ Anderson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , "Peter Zijlstra (Intel)" , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , Marco Elver , "Guilherme G. Piccoli" , Nikunj A Dadhania , "Xin Li (Intel)" , Dimitri Sivanich Subject: Re: [PATCH v3] x86/tsc: Disable clocksource watchdog for TSC on recent UV Message-ID: References: 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=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Flag: NO X-Spam-Score: -3.80 X-Spamd-Result: default: False [-3.80 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MISSING_XM_UA(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[19]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCVD_TLS_LAST(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo] X-Spam-Level: Hello, On Tue, Oct 07, 2025 at 11:32:17AM -0500, Dimitri Sivanich wrote: > Disable clocksource watchdog checking on recent and future UV platforms > to avoid false positives. > > Commits 'b50db7095fe0 ("x86/tsc: Disable clocksource watchdog for TSC on > qualified platforms")' and '233756a640be ("Extend watchdog check exemption > to 4-Sockets platform")' were introduced to avoid an issue where the TSC > is falsely declared unstable by exempting qualified platforms of up to > 4-sockets from TSC clocksource watchdog checking. Extend that exemption > to include recent and future UV platforms. I am sorry for being MIA for all this time. Apart from HPE customers who do not follow the instruction to add tsc=nowatchdog to the kernel command line, there is another use case for this patch. It has to do with SUSE's efforts to ship a single image per product for deploying machines in the cloud. HPE UV systems that will be used as bare metal are one of the planned instances. The old implementation of the clocksource watchdog needs to be switched off on those UV systems. So, the intention is to backport this patch to all SLES releases that are in active use in the cloud. A new implementation of the clocksource watchdog has been merged into the upstream kernel. One of the changes made by the new clocksource watchdog implementation is that reference clocksource reads are made on the boot CPU only. Perhaps, the sgi_rtc clocksource would work well with this implementation. So, testing is needed in order to find out if this patch are any future in the upstream Linux. Dimitri, would you be able to run tests on UV systems to check if the new clocksource watchdog implementation works and the hardware limitations of sgi_rtc do not get in the way? -- Jiri Wiesner SUSE Labs