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 E6A7EC0015E for ; Fri, 28 Jul 2023 16:57:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230081AbjG1Q5b (ORCPT ); Fri, 28 Jul 2023 12:57:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58768 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232604AbjG1Q5T (ORCPT ); Fri, 28 Jul 2023 12:57:19 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 00DE84483 for ; Fri, 28 Jul 2023 09:57:02 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id DABB91F853; Fri, 28 Jul 2023 16:57:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1690563420; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cB3b2RteAJTicCMa04OTTGBeRFsXbKxK1XcIggZI2AU=; b=pTCxgUB467kOJalRwySFTQyubC+ILW17hcRfmTtjm9h/N8CYwIF8WwAWr3VZoKODRG4Tr0 9H93EyqJebhWiAPzdPHkIr56ftVIdVas7pwcqmxhX04CqH708ic/uokq3KgtRS/Gazsihe vu8w7qGJmG+/r1vnsmhnsFt4aVSfkQA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1690563420; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cB3b2RteAJTicCMa04OTTGBeRFsXbKxK1XcIggZI2AU=; b=ZqxqpKb01a+cmTIpv2muvwiVqozzVICBMPbrjfmKe7ErggpqpP1IGHJh73dcjw6JuY4Ihc o4M2uq8kTzoWnFAQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 8EC2613276; Fri, 28 Jul 2023 16:57:00 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id dd5rIFzzw2S8aQAAMHmgww (envelope-from ); Fri, 28 Jul 2023 16:57:00 +0000 Date: Fri, 28 Jul 2023 18:50:37 +0200 From: David Sterba To: Martin Steigerwald Cc: linux-btrfs@vger.kernel.org, Qu Wenruo Subject: Re: [PATCH 0/5] btrfs: scrub: improve the scrub performance Message-ID: <20230728165037.GJ17922@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <6543972.G0QQBjFxQf@lichtvoll.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6543972.G0QQBjFxQf@lichtvoll.de> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Fri, Jul 28, 2023 at 02:38:35PM +0200, Martin Steigerwald wrote: > Qu Wenruo - 28.07.23, 13:14:03 CEST: > > The first 3 patches would greately improve the scrub read performance, > > but unfortunately it's still not as fast as the pre-6.4 kernels. > > (2.2GiB/s vs 3.0GiB/s), but still much better than 6.4 kernels > > (2.2GiB vs 1.0GiB/s). > > Thanks for the patch set. > > What is the reason for not going back to the performance of the pre-6.4 > kernel? Isn't it possible with the new scrubbing method? In that case > what improvements does the new scrubbing code have that warrant to have > a lower performance? Lower performance was not expected and needs to be brought back. A minor decrease would be tolerable but that's something around 5%, not 60%. > Just like to understand the background of this a bit more. I do not mind > a bit lower performance too much, especially in case it is outweighed by > other benefits. The code in scrub was from 3.0 times and since then new features have been implemented, extending the code became hard over time so a bigger update was done restructuring how the IO is done.