From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DAC9BC5CFCF for ; Fri, 14 Aug 2026 22:16:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=jsU+x82WmlajkDCJyuwvAb1ngGFbDbQuk3q0k9VNyK8=; b=Iehf98duYyHhiz8uqZcvRH+C2G WNycglpb6UeizStjR6eYT1/ZGhn8iTT1El/b6QsQ+TySrmiJyE6aMvJJJsvQTZDjYoYuxsG9sRAL2 wYYVDYI5EH3rkGVcP8hcYx1AIcb9rjeRpIp5se7gbYPV2K07qo9io4HCqSvivXV5hhiIEJAs5jWLI T7yx4WLwg4s/O7fnZEi4iRWv3zx9Ox6EpEYZ9o54WFvP7sq8JEans91MMjjQDkDaWBveXvimWKUs9 FoxU6eW7KdeyZHj0GYX628dYAkBOr9BLWK2G3HouxTfHN7fWg03UxkutSEDaMpIIEd13Gp5jxrbBi yfB34lMA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wv0Cd-00000003FtW-0GHv; Fri, 14 Aug 2026 22:16:39 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wv0Cb-00000003FtJ-03dp for linux-nvme@lists.infradead.org; Fri, 14 Aug 2026 22:16:37 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id C072140964; Fri, 14 Aug 2026 22:16:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51E8C1F000E9; Fri, 14 Aug 2026 22:16:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786745795; bh=jsU+x82WmlajkDCJyuwvAb1ngGFbDbQuk3q0k9VNyK8=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=af8HbGgthUZ+fERKOMj72iKEQoh04Cs4ok0rdxM7e7rQ4qbi4xCicToTQwNONSf3F 6HvxA5Rt/5kF8+zh9L7DRYe/v1PfYhVZn1ofXvaDF8SwXXurFMWmKaPPutSBmAhan8 SB41xegzOG5PGGn9WqJna1lVBeOv7+xt2l5RF8jSoOU/LFJguWQDZFZ6krDL6yopZW 0hSLCuZgkU3ON9GMXokQDqzX4AkvgAEXW57aM8FwJBP3CtmlzR2ITxm8kbC2NE9bsU TQRAYYA2Wmt7imHRbZM7rvmuu9/ikH+mG4NSQWttYzTaRwzAeJGJzLaMOdRjF5dzIa 0TMGOg28SwO1g== Date: Fri, 14 Aug 2026 16:16:33 -0600 From: Keith Busch To: Anuj Gupta Cc: changfengnan , axboe@kernel.dk, hch@lst.de, sagi@grimberg.me, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Guzebing , anuj20.g@samsung.com Subject: Re: [RESEND RFC PATCH v2] nvme-pci: add adaptive interrupt polling Message-ID: References: <20260806031058.40176-1-changfengnan@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Thu, Aug 13, 2026 at 09:15:31AM +0530, Anuj Gupta wrote: > > I also had a similar assesment on DIM. Emperically, with Keith's POC > interrupts per IO drop from ~1.0 to ~0.29 but with a small performance > regression (572K -> 557K IOPS). With your original approach they drop to > ~0.03 with a 23% performance gain. The DIM machinery overhead maybe > outweighing the partial interrupt reduction. I may ultimately adandon this suggestion, but it looks like a major factor in performance loss was from using IRQ_WAKE_THREAD with sleep cycles instead of the softirq hrtimer. Just changing that is getting me back to performance parity, but since it's not any better, perhaps the hill climb is a worse algorithm than trying to reason out the delayed poll time directly.