From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BDEC62BDC05 for ; Thu, 31 Jul 2025 09:25:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753953939; cv=none; b=L2WXc9KxwxsVZwTWDLlNcjLzT6AadoFK+/nrXlgg4eNpjEp6A0cuJv8maEvC8S7gl8zRIla3Y8NcFJlMBkHHVaSPLvUze4Nn+9mU6IwJlq25hRmFc6njV/ZEjUFFflNkvN4It+M25I89Qkw2pfywtOy0mHnGMKWYQU6k5Dnq5tc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753953939; c=relaxed/simple; bh=F/kyMRg9amWHy5VNn12meu3kJW8SbR2vDu83nieisB4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZaRoOAjH/3HH60V+BBKDc3sFfAmlZB+2Mw9ZJf4X73tNR8sSTc8pPNEFWSPZKDSJ3V7WNsheKaGbR45SFziqEbWTk7FkAIyNTc1xrezKRZ61hFtcjaVhXAFmqeSqbBfZmH9MvF2YqK7eVS3LL0g0Jb/Wk+tx+8v/BOihUYe7Vr0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=JK4mQJiN; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JK4mQJiN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1753953936; 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=xKeh7VJ5S9c7YzR0dFENlYj0yyHuQf1HeWrzZHEAVrI=; b=JK4mQJiNO4PPg1JYr1JzL41kie/DwakW/oItai6kQOmYXxs9fAVaEB5JJ3UMO7ytbKwSEE Xeca+OZfiN+XqhBIgqssz4Xm0c6VMhpdr2yxCYRAic9YIt2KpPr6zgAidJFY15/KDy7LE/ WTsE7VMy9fVPDE26gRcWQdl/DyNtw7Y= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-118-MKYe2GG6PwSFD4D4UfMOBw-1; Thu, 31 Jul 2025 05:25:32 -0400 X-MC-Unique: MKYe2GG6PwSFD4D4UfMOBw-1 X-Mimecast-MFC-AGG-ID: MKYe2GG6PwSFD4D4UfMOBw_1753953930 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2BA2A180035F; Thu, 31 Jul 2025 09:25:29 +0000 (UTC) Received: from fedora (unknown [10.72.116.62]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BEB5E19776D1; Thu, 31 Jul 2025 09:25:20 +0000 (UTC) Date: Thu, 31 Jul 2025 17:25:15 +0800 From: Ming Lei To: Yu Kuai Cc: dlemoal@kernel.org, hare@suse.de, jack@suse.cz, tj@kernel.org, josef@toxicpanda.com, axboe@kernel.dk, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com, "yukuai (C)" Subject: Re: [PATCH v2 0/5] blk-mq-sched: support request batch dispatching for sq elevator Message-ID: References: <20250730082207.4031744-1-yukuai1@huaweicloud.com> <99e9aa7e-b33c-ce2e-bf0f-0021434690e8@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <99e9aa7e-b33c-ce2e-bf0f-0021434690e8@huaweicloud.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On Thu, Jul 31, 2025 at 04:42:10PM +0800, Yu Kuai wrote: > Hi, > > 在 2025/07/31 16:18, Ming Lei 写道: > > batch dispatch may hurt io merge performance which is important for > > elevator, so please provide test data on real HDD. & SSD., instead of > > null_blk only, and it can be perfect if merge sensitive workload > > is evaluated. > > Ok, I'll provide test data on HDD and SSD that I have for now. > > For the elevator IO merge case, what I have in mind is that we issue > small sequential IO one by one with multiple contexts, so that bios > won't be merged in plug, and this will require IO issue > IO done, is > this case enough? Long time ago, I investigated one such issue which is triggered in qemu workload, but not sure if I can find it now. Also many scsi devices may easily run into queue busy, then scheduler merge starts to work, and it may perform worse if you dispatch more in this situation. Thanks, Ming