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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0112FC433F5 for ; Tue, 15 Mar 2022 14:14:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347714AbiCOOPT (ORCPT ); Tue, 15 Mar 2022 10:15:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349051AbiCOOPR (ORCPT ); Tue, 15 Mar 2022 10:15:17 -0400 Received: from wout5-smtp.messagingengine.com (wout5-smtp.messagingengine.com [64.147.123.21]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1C9B4704D for ; Tue, 15 Mar 2022 07:14:05 -0700 (PDT) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id 4D28E3200A2F; Tue, 15 Mar 2022 10:14:03 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Tue, 15 Mar 2022 10:14:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=georgianit.com; h=cc:cc:content-transfer-encoding:content-type:date:date:from :from:in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:sender:subject:subject:to:to; s=fm3; bh=lNsc7Vo0Ni5o6Y WIH2hy4ImpGC+foIx6KCgLVXarEzM=; b=lFoQDOIJrnYiAj4zmhNb5RIxx3Y+I0 BKcJc2RymvH9JNjnMgjfwy2yStSGMzu1IO/p2D4uQp0yHDNdlZzA2GzdpuIRaTKz 1TlXTITiceVCDD/EjPVwzHnKfDHekcNeVwLiOoWyLAkkzJbPOt/BxoVySnd9Kuob pVEXGjho1tqMTkTRYGz9shtg94EVp9kKjmlwRQyDz3m3K/XIoDJNYsGz0+PyLS9p 5w3bxZ2SerZ3aWKkrFDdGCFbJuIoM2tUAgLb9dKtndfR8xA2xxaTnR6p8O3HyR8f j2KaAi3sqli5/0l9kSw0rX4Ynm8iSQNQuyrUbqYZ1lmks0nXcKjCMGZQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; bh=lNsc7Vo0Ni5o6YWIH2hy4ImpGC+foIx6KCgLVXarE zM=; b=EG4ADOqvSG9IrTweHp3Mh59FCL/bIXTnnAS9r7wpw+8HWEbU/bAKMGdBy mjMX7IUiSl0Plc73UjJy87siu96CTIC62+u952JJ8JEwSal85DPti+pujDT93hZc q6u8B6GtQhZTJSNSIGIiCH8ztOTrJGowt6iFj+h1xKULaxgY0p1QvPP4orYUdrVZ llkc2/sgsghZv7lvH+//VU6BWKyn2jU9/TGwE0vZKCASsTDK8m5m4KmJTWIlOEea D0sd/FbWix7DWEL4itzC9zYJOut1vzaHEQmtGkCUb6Lfdx0+i97KbrANrVHciEVk cu/HhxVubxx7n8BEXjjFokmRDd0kg== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvvddrudeftddgieduucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefvfhfhuffkffgfgggjtgfgsehtke ertddtfeejnecuhfhrohhmpeftvghmihcuifgruhhvihhnuceorhgvmhhisehgvghorhhg ihgrnhhithdrtghomheqnecuggftrfgrthhtvghrnhepheejhfetudduffffgfduheeive dtleekffeludekhfehheffuefggeegkeejiedunecuvehluhhsthgvrhfuihiivgeptden ucfrrghrrghmpehmrghilhhfrhhomheprhgvmhhisehgvghorhhgihgrnhhithdrtghomh X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 15 Mar 2022 10:14:02 -0400 (EDT) To: Zygo Blaxell Cc: linux-btrfs References: <87tuc9q1fc.fsf@vps.thesusis.net> <87tuc7gdzp.fsf@vps.thesusis.net> <87ee34cnaq.fsf@vps.thesusis.net> <23441a6c-3860-4e99-0e56-43490d8c0ac2@georgianit.com> From: Remi Gauvin Subject: Re: Btrfs autodefrag wrote 5TB in one day to a 0.5TB SSD without a measurable benefit Message-ID: Date: Tue, 15 Mar 2022 10:14:01 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 2022-03-14 7:39 p.m., Zygo Blaxell wrote: > > If we're adding a mount option for this (I'm not opposed to it, I'm > pointing out that it's not the first tool to reach for), then ideally > we'd overload it for the compressed batch size (currently hardcoded > at 512K). Are there any advantages to extents larger than 256K on ssd Media? Even if a much needed garbage collection process were to be created, the smaller extents would mean less data would need to be re-written, (and potentially duplicated due to snapshots and ref copies.) The fine details on how to implement all of this is way over my head, but it seemed to me like the logic to keep the extents small is already more or less already there, and would need relatively very little work to manifest.