From mboxrd@z Thu Jan 1 00:00:00 1970 From: "John Daley (johndale)" Subject: Re: [PATCH v3 07/13] enic: use Tx completion messages instead of descriptors Date: Fri, 10 Jun 2016 22:28:01 +0000 Message-ID: <6fdf2e090a4142a5ba4e3b78086267a5@XCH-RCD-007.cisco.com> References: <1464071579-30072-1-git-send-email-johndale@cisco.com> <1464913377-30879-1-git-send-email-johndale@cisco.com> <1464913377-30879-8-git-send-email-johndale@cisco.com> <20160610211813.GA15176@bricha3-MOBL3> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Cc: "dev@dpdk.org" , "bruce.richarsdon@intel.com" To: Bruce Richardson Return-path: Received: from rcdn-iport-3.cisco.com (rcdn-iport-3.cisco.com [173.37.86.74]) by dpdk.org (Postfix) with ESMTP id 07DB02A07 for ; Sat, 11 Jun 2016 00:28:02 +0200 (CEST) In-Reply-To: <20160610211813.GA15176@bricha3-MOBL3> Content-Language: en-US List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" > -----Original Message----- > From: Bruce Richardson [mailto:bruce.richardson@intel.com] > Sent: Friday, June 10, 2016 2:18 PM > To: John Daley (johndale) > Cc: dev@dpdk.org; bruce.richarsdon@intel.com > Subject: Re: [dpdk-dev] [PATCH v3 07/13] enic: use Tx completion messages > instead of descriptors >=20 > On Thu, Jun 02, 2016 at 05:22:51PM -0700, John Daley wrote: > > The NIC can either DMA a separate completion message for each > > completed send or periodically just DMA an index of the last completed > > send. Switch to the second method which improves cache locality and > > performance. > > > > Signed-off-by: John Daley >=20 > Can you perhaps send me an updated wording for this commit message as > the title and commit message conflict. The title says to use completion > messages not descriptors, while the body talks about moving away from a > completion message way of working. > Is the former method a descriptor writeback method, while the latter a he= ad > pointer writeback? If so, I think the title could be: >=20 > "enic: use Tx head pointer not descriptor writeback" >=20 > or something similar. >=20 > Again, if you send on the updated commit text, I'll just update it on app= ly. I'd > ideally like to get this patchset pushed to next-net first thing Monday. Ok, I agree that it is confusing. We moved from having the hardware send a completion descriptor for every pa= cket to having it send the index of the last completed packet every once in= a while. We can use the word 'index' and 'message' to describe the 2 metho= ds and drop the word 'descriptor'. Here is a suggestion: enic: use Tx completion index instead of completion messages The NIC can either DMA a separate completion message for each completed sen= d or periodically just DMA an index of the last completed send. Switch to t= he latter method which improves cache locality and performance. Thank you, John >=20 > /Bruce