From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Lameter Subject: Re: [PATCH for-next V2 0/9] Add completion timestamping support Date: Wed, 3 Jun 2015 19:55:58 -0500 (CDT) Message-ID: References: <1433074457-26437-1-git-send-email-ogerlitz@mellanox.com> <1433098827.114391.179.camel@redhat.com> <1433157904.114391.188.camel@redhat.com> <20150601164322.GA14391@obsidianresearch.com> <1433255724.114391.225.camel@redhat.com> <20150602180844.GD17776@obsidianresearch.com> <20150603204633.GE7902@obsidianresearch.com> Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: In-Reply-To: <20150603204633.GE7902-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jason Gunthorpe Cc: Or Gerlitz , Doug Ledford , Matan Barak , Or Gerlitz , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Amir Vadai , Tal Alon List-Id: linux-rdma@vger.kernel.org On Wed, 3 Jun 2015, Jason Gunthorpe wrote: > MHz is fine *for mlx hardware* but someone elses hardware that uses, > say 312.5 MHz (ie the ethernet symbol clock) is NOT OK because MHz > looses too much precision. Oscillator vary in frequency. In order to accurately convert to NS the drift due to temperature etc needs to be taken into consideration. The "ns" value there is pretty rough as well. Accurate time may need time software to continually monitor the *actual* frequency of the oscillator. I thknk the raw cycles and the rought oscillator speed are fine. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html