From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 29EE621ABAA for ; Fri, 22 May 2026 08:03:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779436984; cv=none; b=UOjMNVfoXxMk0g4HANil8zoAQRRV10IzvhIr9w/Nxc4vPC0/voJnYWw4WrhCrZPXmtJxJFGjZEZkfcSTfdPUR2Bd7qopI+NyYqbuLBE3pBlGZGf2Et05mafDL+lwHtS3xvo3Ai68T+4LTJrZVxKsQAf27sGh9WdZYHpKXaSfpx0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779436984; c=relaxed/simple; bh=bLHNW91Ut0l12qvdLfCEOJaxhvE2J+uLHry5QtikrYY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=oKd58q8HBLZJId6NkJdJatEWg7VZ0jvi/vAxjOxhjidmEBOeZZXeoE6rQmLw2gGzaOzzeY+UtC5e0N2h9p2TNxY5zj253g46HX4MBINLM0EIoKZp+vxdp2cHhYvNzQNyKeNvwA6zqLXLn5v3VDmc/INwDTyuN9tqiQou/zpWYrs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EENLwacW; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EENLwacW" Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id EAFEF1F000E9; Fri, 22 May 2026 08:03:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779436982; bh=6q0Z3PeIlNHU4B/1AsG6NJz3W5sChRJ0VJIMYY/cSlo=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=EENLwacWWpxAn9EOc5rpcN7iA3J82Iw6Oblq0Hem4Vj8XE/77R6tnRTDitGYaqjdb Ou1QkqKvzl+1YdycKsDTO6VkiGnKPwiygx0HMq0Yz8K4vS/g7RVIcoG5VHByTeTGrv 5r2o7E9Kr7v+ZTeTLaOq1tEqihwCxqxwTabt7Vwd1D6K4AxO3GvGdblo2G9arRPN82 X64MOrRSoCJimOYGeEJmBt406/3a4uz/f5CYwJfHnfIP0q3N7eXSYZjkfwnUHaTk4T yuNo/sTrkvgmkpVyrGxfJEg9WQmf9bbMEBpSn7Mu86zTQkC4LCfyKswiKV5bI8PkEa M6kkv3giyyN9g== From: Thomas Gleixner To: David Woodhouse , Miroslav Lichvar Cc: Richard Cochran , Wen Gu , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , John Stultz , Stephen Boyd , Anna-Maria Behnsen , Frederic Weisbecker , Shuah Khan , Peter Zijlstra , Thomas =?utf-8?Q?Wei=C3=9Fschuh?= , Arnd Bergmann , Julien Ridoux , Ryan Luu , linux-kernel@vger.kernel.org, Marcelo Tosatti Subject: Re: [RFC PATCH v2 0/8] timekeeping: Fix draft tracking precision and add feed-forward discipline via vmclock In-Reply-To: <6c7137748ccea288fdf55e7c2e24817ccc1673ef.camel@infradead.org> References: <20260517220326.4625-1-dwmw2@infradead.org> <0d32da75fa88c92ac0225ef23a9045afdf2ac9fe.camel@infradead.org> <87o6i8vcni.ffs@tglx> <6c7137748ccea288fdf55e7c2e24817ccc1673ef.camel@infradead.org> Date: Fri, 22 May 2026 10:02:59 +0200 Message-ID: <874ijzvpl8.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; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Thu, May 21 2026 at 22:06, David Woodhouse wrote: > On Thu, 2026-05-21 at 20:30 +0200, Thomas Gleixner wrote: >>=20 >> As I said in the other thread, that's just creating yet another private >> mechanism instead of collecting the counter value together with e.g. >> CLOCK_REALTIME=C2=A0 > > On the plus side, at least he wasn't providing a counter value at *all* > for the system timestamps, which is better than using a bogus one :) At least ... for now :) > Can we have a signed-off-by for your ktime_get_snapshot_id() please? Are you kidding? That's a PoC to demonstrate how it should be done and it needs some thought to implement it correctly along with the get_device_cross_timestamp() one, which is actually not entirely correct as I noticed a few minutes ago. >> or utilizing the PMT correlated one which is available in >> get_device_crosstime_stamp(). > > AFAICT that was the *only* one he was exposing, wasn't it? The vmclock > driver literally did expose the cycle count used to create the device > timestamp, which is equivalent to PTM and looked correct for that > part? The vmclock driver lives in it's own made up world, so yes this looks consistent on the first glance. Thanks, tglx