From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [LSF/MM TOPIC][LSF/MM ATTEND] NAPI polling for block drivers Date: Wed, 11 Jan 2017 09:15:26 -0700 Message-ID: <5b2229ee-a225-b59f-ccdf-710767941920@kernel.dk> References: <20170111134312.GH6286@linux-x5ow.site> <1484150893.2619.1.camel@sandisk.com> <20170111161238.GA18881@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-it0-f48.google.com ([209.85.214.48]:37745 "EHLO mail-it0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758056AbdAKQP3 (ORCPT ); Wed, 11 Jan 2017 11:15:29 -0500 Received: by mail-it0-f48.google.com with SMTP id r185so76702169ita.0 for ; Wed, 11 Jan 2017 08:15:28 -0800 (PST) In-Reply-To: <20170111161238.GA18881@infradead.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "hch@infradead.org" , Bart Van Assche Cc: "jthumshirn@suse.de" , "lsf-pc@lists.linux-foundation.org" , "Linux-scsi@vger.kernel.org" , "keith.busch@intel.com" , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" , "sagi@grimberg.me" On 01/11/2017 09:12 AM, hch@infradead.org wrote: > On Wed, Jan 11, 2017 at 04:08:31PM +0000, Bart Van Assche wrote: >> A typical Ethernet network adapter delays the generation of an interrupt >> after it has received a packet. A typical block device or HBA does not delay >> the generation of an interrupt that reports an I/O completion. > > NVMe allows for configurable interrupt coalescing, as do a few modern > SCSI HBAs. Unfortunately it's way too coarse on NVMe, with the timer being in 100 usec increments... I've had mixed success with the depth trigger. -- Jens Axboe