From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (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 lists.proxmox.com (Postfix) with ESMTPS id C8BA1F373 for ; Thu, 15 Dec 2022 10:59:11 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id ACBC85CCF for ; Thu, 15 Dec 2022 10:59:11 +0100 (CET) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS for ; Thu, 15 Dec 2022 10:59:09 +0100 (CET) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id AF039443A8 for ; Thu, 15 Dec 2022 10:59:09 +0100 (CET) From: Fiona Ebner To: pve-devel@lists.proxmox.com Date: Thu, 15 Dec 2022 10:59:06 +0100 Message-Id: <20221215095906.46835-1-f.ebner@proxmox.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL -0.472 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment KAM_EVIL_NUMBERS4 1 Phone Numbers used by scammers SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record URIBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [proxmox.com] Subject: [pve-devel] [PATCH docs] qm: IO thread: be more precise about how QEMU handles IO X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Dec 2022 09:59:11 -0000 Reported in the community forum[0]. The setting can already help with a single disk. Without the option, there is not one IO thread as the old wording suggested, but IO is handled in the main event loop or vCPU threads (see the kvm man page). [0]: https://forum.proxmox.com/threads/118390/post-518532 Signed-off-by: Fiona Ebner --- qm.adoc | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/qm.adoc b/qm.adoc index f923ccf..fb11e29 100644 --- a/qm.adoc +++ b/qm.adoc @@ -249,12 +249,11 @@ Note that *SSD emulation* is not supported on *VirtIO Block* drives. [[qm_hard_disk_iothread]] IO Thread ^^^^^^^^^ -The option *IO Thread* can only be used when using a disk with the -*VirtIO* controller, or with the *SCSI* controller, when the emulated controller - type is *VirtIO SCSI single*. -With this enabled, Qemu creates one I/O thread per storage controller, -rather than a single thread for all I/O. This can increase performance when -multiple disks are used and each disk has its own storage controller. +The option *IO Thread* can only be used when using a disk with the *VirtIO* +controller, or with the *SCSI* controller, when the emulated controller type is +*VirtIO SCSI single*. With *IO Thread* enabled, Qemu creates one I/O thread per +storage controller, rather than handling all I/O in the main event loop or vCPU +threads. This can increase performance, because of improved work distribution. [[qm_cpu]] -- 2.30.2