From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Cochran Date: Wed, 21 Mar 2018 07:59:30 -0700 Subject: [Intel-wired-lan] [RFC v3 net-next 08/18] net: SO_TXTIME: Add clockid and drop_if_late params In-Reply-To: References: <20180307011230.24001-1-jesus.sanchez-palencia@intel.com> <20180307011230.24001-9-jesus.sanchez-palencia@intel.com> <1520391209.109662.33.camel@gmail.com> <20180307052410.m2yqmokrivjlwcjz@localhost> Message-ID: <20180321145930.4hlmihghljpv2wrq@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: On Wed, Mar 21, 2018 at 01:58:51PM +0100, Thomas Gleixner wrote: > Errm. No. There is no way to support fd based clocks or one of the CPU > time/process time based clocks for this. Why not? If the we have HW offloading, then the transmit time had better be expressed in terms of the MAC's internal clock. Otherwise we would need to translate between a kernel clock and the MAC clock, but that is expensive (eg over PCIe) and silly (because in a typical use case the MAC will already be synchronized to the network time). Thanks, Richard