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 E25FAC79F8B for ; Sat, 5 Sep 2026 20:30:39 +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:Content-Transfer-Encoding: Content-Type:MIME-Version:Message-ID:Date:References:In-Reply-To:Subject:Cc: To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=hwgSr9LF1AaQKstntdYXF4tsMbm8X5Lx15fwX+9hr5k=; b=ABBi6vPPCHcx7s/A6ir5sAwrsm WcILWJIkNxA2SkZal7Bwym/sGnI+jNUYBVLMkbbEFtxl7vNItsGxvZpaQBQgEVlEOwCLlsRu02BK6 gefb90EtpFsSaLyUm5A3DRBrSGLti8xmcDs5P5QPvknDS8JCTtXSABhHoRF7qtb4+A9agZL5ktLd0 fGL/MVFfk+EMv9NUmEi78NSIQXXsb2e3N87n5ORAYFgi8/MN7zaOOlMzIFLxsxSiW/tFvWKdZ6prj MSAKCOImjwsvIzG6bo+kHbEQ1iSnkH6rhAlAT/yTampR4uSnZpYbWqL+t83W4S35i/acVnhwrw5K8 oNvXmpkQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x2x21-00000004OoU-1yEs; Sat, 05 Sep 2026 20:30:33 +0000 Received: from galois.linutronix.de ([193.142.43.55]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x2x1v-00000004Oo2-1cx9 for linux-nvme@lists.infradead.org; Sat, 05 Sep 2026 20:30:28 +0000 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1788640223; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hwgSr9LF1AaQKstntdYXF4tsMbm8X5Lx15fwX+9hr5k=; b=skPCZuyWro0VW6391LtWlzrr/B1W1w/re6wD9oT3npVcauGo05kkwL78ny2VUxbQ4h4nbp cj5IQ+1A4obQd3tT2NMZcEwGhi0c5VkXgIW/swYV/fKuOcb60G6nAD8BMfDY97pE5EUxdz N+J4pmuFMOZgRS3xtYHK/ZLzjFjp1dz85hlulDsMZKKwBjhzlReZuhzkcRzKmSkLjNUSNz p/+UYHaNiWMKrbJoxMk+kuMyrENVwuJh78/3RcXtrncBlBwN8CAy2nzvj42sWOKRkXJG8U 2zmQrWEee/uqKDmY/58HJDUl+wCj1r8M31dMqCCj0QvWtKV3vswOf73AZpTpNA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1788640223; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hwgSr9LF1AaQKstntdYXF4tsMbm8X5Lx15fwX+9hr5k=; b=xClnT4gxHr/HnwlWOjClcB0G5DjEE+jqWtE0d0pRDLr92cUPXaH+71Z+zm3v2cOwKwImZi iqdeo1gS0rmQ50CQ== To: changfengnan , Luigi Rizzo Cc: Christoph Hellwig , Marc Zyngier , Luigi Rizzo , Paolo Abeni , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Bjorn Helgaas , netdev@vger.kernel.org, linux-nvme@lists.infradead.org Subject: Re: [PATCH v5 0/7] Global Software Interrupt Moderation (GSIM) In-Reply-To: References: <20260819124341.4185621-1-lrizzo@google.com> Date: Sat, 05 Sep 2026 22:30:22 +0200 Message-ID: <878q5f5tlt.ffs@fw13> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260905_133027_576851_7CE134E2 X-CRM114-Status: GOOD ( 15.36 ) 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 20 2026 at 19:46, changfengnan@bytedance.com wrote: >> From: "Luigi Rizzo" >> Date:=C2=A0 Thu, Aug 20, 2026, 15:35 >> Subject:=C2=A0 Re: [PATCH v5 0/7] Global Software Interrupt Moderation (= GSIM) >> To: "Christoph Hellwig" >> Cc: "Thomas Gleixner", "Marc Zyngier", "Luigi Rizzo", "Paolo Abeni", = , , "Bjorn Helgaas= ", , , "Fengnan Chang" >> On Thu, Aug 20, 2026 at 9:09=E2=80=AFAM Christoph Hellwig wrote: Can you please fix yuur mail client so it does not copy all that redundant headers into your reply? >> > Also how does this interact with adaptive polling code inside drivers >> > like NAPI or the upcoming nvme variant? >>=C2=A0 >> GSIM acts at hardirq level (so below NAPI, and above device moderation e= .g. >> the one in ethtool -C ...) and is completely orthogonal to those other >> mechanisms. > > Hi Luigi: > The NVMe variant that Christoph mentioned is this patch of mine. > https://lore.kernel.org/linux-nvme/d9210bcdf73fbe1ac8b6ec132865609a3ed686= 88.99d43a8b.dfff.41d1.b07d.0592a12473d2@bytedance.com/T/#m561d1366119620556= 41f331e600e719de1e7c573 > I took a quick look at your implementation, and I wouldn't say our two > approaches are completely independent. > I=E2=80=99ve run some tests, the test methods, environment, and data are = detailed in > this document: > https://docs.google.com/spreadsheets/d/1p3XqVpKgx18QhqTFb0KlJfEW9giWDGSUu= oKqCZzdZLg/edit?gid=3D1100001004#gid=3D1100001004 > > it appears that GSIM is only effective in scenarios where multi disks at = very high > IOPS; in some cases, there was a noticeable performance regression.=C2=A0 > If there=E2=80=99s something wrong with my configuration, please correct = me. So we have a NVME specific mechanism to tackle the same problem and a more generic version which is subsystem "independent". Can you folks please coordinate and get your act together so that we don't end up with two competing mechanisms which make things worse than they are now. TBH. I despise the NVME is special approach because it's fricking obvious that this is _NOT_ a NVME specific issue. But sure NVME is special as all other subsystems are special. Q: When do driver folks actually start to look beyond the brim of their tea cup? A: Probably never ... Thanks, tglx