From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0EFCA3624D4; Wed, 1 Apr 2026 19:37:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775072244; cv=none; b=sSK6QypSSSCT8A8JqqNOrxAEgwGVvzxuQwQ4TyQFV90E332og8bwQTwVSlr9WAwl+Gqh1KE6uHsZ2vZhNe0/cyvt4GnPqgPmnDdVKtSNdabY8KFct9+zEUJbAtp0UFVN7aufvbPGkR03juGd0+q4/tCYdMHKVmoqQB+vd4hZIJo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775072244; c=relaxed/simple; bh=eKiFTT1ZlkeE5A5Gd+8gkkUl2okHYY0q+wXdr6il8xQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=oilEG4P7mNGggWipZO+msVHJ/oI47Ix0o7zAHYLLEV+wVucX1L1IUge6bdP10Sd3HWLaFdDGGc58M91Yohov1edDlLfTo5fzGWWMUZypTUyTCshykW/WbBr1SVSMNvlNJl+qITQ88Mn1hQZdJT8AxebdSUDXtvzlJVB7cCGRxk8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=umVDHa8g; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="umVDHa8g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29DE4C4CEF7; Wed, 1 Apr 2026 19:37:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775072243; bh=eKiFTT1ZlkeE5A5Gd+8gkkUl2okHYY0q+wXdr6il8xQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=umVDHa8gUXwRGSI+9JpfG/Xazi8yFmBXEhLpWU7yrAvfN6qz1FKcjioR9Ctf9DS2u amWG2D8VViEmr+Pki0AY5M5dLiqzSVz2Tbq2/U0i258pQ9NNhUdNf8fb4Qlk/b6yQD zPtJ1bKx7KkkIqaTvIENamru679rIU9PPvapvaLSAeFrlWcvjWulZtvYs4U2rMqSOu QK1qzl9051sEAF86R0daqFGoAgx1H0dE9lSK+2mlCQBz5h4vzNDAnDRg91KVqX21G0 aE+kASEsiNy6mIer8K0qGAFq3y2Wu1T9CQjTE+y/BQH7QJvt2Jz8OE/WY7UkBtlHJQ nMbQQiEwo5gMQ== From: Thomas Gleixner To: Steven Rostedt Cc: "Bird, Tim" , "pmladek@suse.com" , "senozhatsky@chromium.org" , Shashank Balaji , "john.ogness@linutronix.de" , "francesco@valla.it" , "geert@linux-m68k.org" , "linux-embedded@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v3] printk: fix zero-valued printk timestamps in early boot In-Reply-To: <20260401111244.5057a89c@gandalf.local.home> References: <39b09edb-8998-4ebd-a564-7d594434a981@bird.org> <20260210234741.3262320-1-tim.bird@sony.com> <87zf3ud92r.ffs@tglx> <87jyuvboo2.ffs@tglx> <87jyus9xft.ffs@tglx> <87ldf78tc5.ffs@tglx> <20260331200519.58930ece@gandalf.local.home> <87h5pv84h5.ffs@tglx> <20260401111244.5057a89c@gandalf.local.home> Date: Wed, 01 Apr 2026 21:37:20 +0200 Message-ID: <87tstu79qn.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Wed, Apr 01 2026 at 11:12, Steven Rostedt wrote: > On Wed, 01 Apr 2026 10:33:26 +0200 > Thomas Gleixner wrote: >> As I've demonstrated the time until the first time stamp is available >> has nothing to do with the number of CPUs and is more or less constant: > > So my question is, if something changes in this time frame, where it goes > from 30ms to 300ms, how would we find out? > > Again, for Chromebooks, we get these timestamps from the firmware and it's > very useful. I understand all of that and I'm not opposed to make that happen if it's integrated properly into sched clock as I demonstrated with the PoC hack. Thanks, tglx