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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 E5044C36008 for ; Wed, 26 Mar 2025 05:39:43 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1txJTY-0003NF-Gv; Wed, 26 Mar 2025 01:38:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1txJTS-0003Mq-SW for qemu-devel@nongnu.org; Wed, 26 Mar 2025 01:38:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1txJTQ-0005hQ-7l for qemu-devel@nongnu.org; Wed, 26 Mar 2025 01:38:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1742967522; 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: in-reply-to:in-reply-to:references:references; bh=q+dcLXC/15M/sFI5qSwuwlJhmvzVGh2puUHpfwp7v2I=; b=ZOWXCfKicmkR7sEt4ffDiTk3Z2EKaixNFuiypwJzc7hT1CUP2qV+VjXIGpimuPJp1XfD2r BIQq8ICrhX1eJNirmVDMyyIlBdfczHI23vB3aoDCdLVJnYWAf7tvY8Ysaq9qel2kclNA9y gLHvZXN3esynN2C4g2V5rFD54ZMcz7s= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-345-bXzdUSDJN_ag074U4LH9uQ-1; Wed, 26 Mar 2025 01:38:38 -0400 X-MC-Unique: bXzdUSDJN_ag074U4LH9uQ-1 X-Mimecast-MFC-AGG-ID: bXzdUSDJN_ag074U4LH9uQ_1742967517 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 692A7196D2CC; Wed, 26 Mar 2025 05:38:36 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.22.74.4]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 33919180B492; Wed, 26 Mar 2025 05:38:35 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 4E74421E66C7; Wed, 26 Mar 2025 06:38:32 +0100 (CET) From: Markus Armbruster To: Hanna Czenczek Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, Kevin Wolf Subject: Re: [PATCH 14/15] fuse: Implement multi-threading In-Reply-To: <20250325160655.119407-13-hreitz@redhat.com> (Hanna Czenczek's message of "Tue, 25 Mar 2025 17:06:54 +0100") References: <20250325160529.117543-1-hreitz@redhat.com> <20250325160655.119407-13-hreitz@redhat.com> Date: Wed, 26 Mar 2025 06:38:32 +0100 Message-ID: <87sen0fj1j.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hanna Czenczek writes: > FUSE allows creating multiple request queues by "cloning" /dev/fuse FDs > (via open("/dev/fuse") + ioctl(FUSE_DEV_IOC_CLONE)). > > We can use this to implement multi-threading. > > Note that the interface presented here differs from the multi-queue > interface of virtio-blk: The latter maps virtqueues to iothreads, which > allows processing multiple virtqueues in a single iothread. The > equivalent (processing multiple FDs in a single iothread) would not make > sense for FUSE because those FDs are used in a round-robin fashion by > the FUSE kernel driver. Putting two of them into a single iothread will > just create a bottleneck. > > Therefore, all we need is an array of iothreads, and we will create one > "queue" (FD) per thread. [...] > Signed-off-by: Hanna Czenczek > --- > qapi/block-export.json | 8 +- > block/export/fuse.c | 214 +++++++++++++++++++++++++++++++++-------- > 2 files changed, 179 insertions(+), 43 deletions(-) > > diff --git a/qapi/block-export.json b/qapi/block-export.json > index c783e01a53..0bdd5992eb 100644 > --- a/qapi/block-export.json > +++ b/qapi/block-export.json > @@ -179,12 +179,18 @@ > # mount the export with allow_other, and if that fails, try again > # without. (since 6.1; default: auto) > # > +# @iothreads: Enables multi-threading: Handle requests in each of the > +# given iothreads (instead of the block device's iothread, or the > +# export's "main" iothread). When does "the block device's iothread" apply, and when "the export's main iothread"? Is this something the QMP user needs to know? > +# For this, the FUSE FD is duplicated so > +# there is one FD per iothread. (since 10.1) Is the file descriptor duplication something the QMP user needs to know? > +# > # Since: 6.0 > ## > { 'struct': 'BlockExportOptionsFuse', > 'data': { 'mountpoint': 'str', > '*growable': 'bool', > - '*allow-other': 'FuseExportAllowOther' }, > + '*allow-other': 'FuseExportAllowOther', > + '*iothreads': ['str'] }, > 'if': 'CONFIG_FUSE' } > > ## [...]