From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH rfc 0/5] generic adaptive IRQ moderation library for I/O devices Date: Tue, 6 Feb 2018 11:34:04 +0200 Message-ID: <73df42b8-106d-0c06-45e2-49285ed01ab5@grimberg.me> References: <20180205220316.30236-1-sagi@grimberg.me> <4c8a45cb-bd4b-8dce-b8d2-2d26c471ef7b@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4c8a45cb-bd4b-8dce-b8d2-2d26c471ef7b@mellanox.com> Content-Language: en-US Sender: linux-block-owner@vger.kernel.org To: Tal Gilboa , Or Gerlitz Cc: linux-block@vger.kernel.org, RDMA mailing list , Jason Gunthorpe , Christoph Hellwig , Jens Axboe , Idan Burstein , Bart Van Assche List-Id: linux-rdma@vger.kernel.org Hi Tal, >> I think Tal has idea/s on how the existing library can be changed to >> support more modes/models >> > What I was thinking is allowing DIM algorithm to disregard data which is > 0. Currently if bytes == 0 we return "SAME" immediately. We can change > it to simply move to the packets check (which may be renamed to > "completions"). This way you could use DIM while only optimizing to (P1) > high packet rate and (P2) low interrupt rate. That was exactly where I started from. But unfortunately it did not work well :( From my experiments, the moderation was all over the place failing to converge. At least the workloads that I've tested with, it was more successful to have a stricter step policy and pulling towards latency if we are consistently catching single completion per event. I'm not an expert here at all, but at this point, based on my attempts so far, I'm not convinced the current net_dim scheme could work.