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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E2216FF885E for ; Mon, 27 Apr 2026 10:51:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2E4636B008C; Mon, 27 Apr 2026 06:51:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 295ED6B0092; Mon, 27 Apr 2026 06:51:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 15DB66B0093; Mon, 27 Apr 2026 06:51:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 0268F6B008C for ; Mon, 27 Apr 2026 06:51:18 -0400 (EDT) Received: from smtpin15.hostedemail.com (lb01b-stub [10.200.18.250]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 9ED38C0372 for ; Mon, 27 Apr 2026 10:51:18 +0000 (UTC) X-FDA: 84704019036.15.CA5A9B6 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf24.hostedemail.com (Postfix) with ESMTP id EB1EA180009 for ; Mon, 27 Apr 2026 10:51:16 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=J6S5CIiR; spf=pass (imf24.hostedemail.com: domain of jlayton@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=jlayton@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1777287077; h=from:from:sender: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:dkim-signature; bh=+s+jvyR4tVTm7frnUubATJ33G+0M/yXy2HB+sdsgbhs=; b=KlCTy4aTUD19UN8YE+8jzofj+Z2oAZN3FRED6HPi+2AK/mVoKkWOAzv9Wx+ljY0LChuMb2 muriTyaDL0BIxOMF3AL8yiW/UsF3IHE+3GVR8FXnILmY6L9Rkql3qNvCoJ5fpHMz83X89u S/92CQwMg1CkIXM8Aj9HpvWv6o9dZNo= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=J6S5CIiR; spf=pass (imf24.hostedemail.com: domain of jlayton@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=jlayton@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1777287077; a=rsa-sha256; cv=none; b=KQpCHGVbg3Dvj+ou1mAKGiQ2jskLyxgagXk3ylEQ7PI/OHJNYNUqZa1xMeBP8hsGcBXbAJ eo4oy2FBaf6N1iu8GQtaqvO1dIz1NmKKtwdOAoRk3vUKLIEFx5mdn8bIfIDDvAmWJLyDEj k/osNnAPpDdQ7NQpMkHcZhM1ysuhRuU= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 42E0B60172; Mon, 27 Apr 2026 10:51:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B2D2C19425; Mon, 27 Apr 2026 10:51:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777287075; bh=4y5Hx2p1vfu1q6BX9Nc9yJRTCjDae/1D0McLv8t6YTM=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=J6S5CIiRa1hWNaETencFFnmkhauL2uLmQ4xAcfCSHFSp4l4k/ekAF1+quBzg4NbQ2 Tqyd5GRu/aEDA0asIOYFH+ircHMN78CQKpHNZNkPzYP6w60dXmWICU8wlWsF6d4u43 CDXAHomkg2d4IKoKgsBp9fRERU1lej7BhnTJmKhAFIcwmX1C55NRtqx+h9/9C0D1g6 5oBHHL5oGl+UfpYp62dXFp0lfLADZbXBTjncWjrpjGWbnPvmHLC/EmVaKfBv2Y8fHn ZHuUHMciTEPJ1WZhrkvOoBNey+nLDBICmObfl5Qz63DcxYAOots+b7JMkDt1z3DGoY FDtZ4m7RUwQQw== Message-ID: Subject: Re: [PATCH v3 2/4] mm: kick writeback flusher for IOCB_DONTCACHE with targeted dirty tracking From: Jeff Layton To: Matthew Wilcox Cc: Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Mike Snitzer , Jens Axboe , Ritesh Harjani , Christoph Hellwig , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Chuck Lever , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Date: Mon, 27 Apr 2026 11:51:07 +0100 In-Reply-To: References: <20260426-dontcache-v3-0-79eb37da9547@kernel.org> <20260426-dontcache-v3-2-79eb37da9547@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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 dr5pX53v aHRrUCU9clr0D6dmQswadNEX17gxRdSETwi8xMSOlYYahCTpxDpxeFdTnf3TgxnnWIXDHRhUXci66Abiuid1XsyMnya+d5tQWTBFea/Dq1XdUJxw1DbHcCV5Fa9gp34kZ/XDaH0uVUbHH4LTTzA+Sb5ydJqWstxxWjk4Dhcw+yh9DMITJ4mdN6QHNIi2hOLfAGtv4bB+2zUSl2nIFgBg2CKp24o8RRsvs8ATEhpBMTkLZ3TWs0Wu269WRcsHclOhy8poqYxFQhybd6jOSeM7Z5RmYUPvSu3B+sy4kJPeHiHouPFLbS6XD5291/UmDMwS0B2lb+dr6eTIgPnJ86ny1dwHht/KPTrKhCR+YCejnON5SHe8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, 2026-04-26 at 21:44 +0100, Matthew Wilcox wrote: > On Sun, Apr 26, 2026 at 07:56:08AM -0400, Jeff Layton wrote: > > Mixed-mode noisy neighbor (dontcache writer + buffered readers): > > baseline patched change > > writer (MB/s) 1297.6 1471.1 +13.4% > > readers avg (MB/s) 855.0 462.4 -45.9% >=20 > hm. This wasn't what I thought of when I thought of "noisy neighbour". > I'd have process A doing DONTCACHE writes to file A and process B doing > normal buffered writes to file B. Originally, I was benchmarking this via nfsd and only later did I add the suite for local benchmarks. With nfsd, setting the iomode affects all reads or writes. So initially, I had it testing them with both reads and writes set to the same setting, but then later I decided to play with different modes for reads and writes. The best performing one was buffered reads + dontcache writes. It's possible a mix of different modes will be better on a local fs. I can't easily do a benchmark like you're suggesting with nfsd, but it should be possible on a local benchmark. I'll see what I can come up with. Thanks, --=20 Jeff Layton