From owner-freebsd-virtualization@FreeBSD.ORG Sun May 10 13:17:02 2015 Return-Path: Delivered-To: freebsd-virtualization@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id F3240AB5 for ; Sun, 10 May 2015 13:17:01 +0000 (UTC) Received: from mail2.openmailbox.org (mail2.openmailbox.org [62.4.1.33]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id B38CB1CA8 for ; Sun, 10 May 2015 13:17:01 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mail2.openmailbox.org (Postfix) with ESMTP id D1A9820345E; Sun, 10 May 2015 15:16:51 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=openmailbox.org; h=user-agent:message-id:references:in-reply-to:subject:subject :from:from:date:date:content-transfer-encoding:content-type :content-type:mime-version:received:received; s=openmailbox; t= 1431263810; bh=9BN6HXpijYHFNGam0wRCKNEuHj2xxjnEkjrp3xkckT4=; b=c BpDjP/MIqEilcjckdI4LbBGDoRD7VXoTazRDOOoDjPmZZv399yzpasZ1b9UnpKYC Oykf05AfVcxyMDr8QjYefeZf37pgFSDAS7+nWWfQm9UX1fzm+8NTvpM3MF/P0mWI 7xFqHUYngDdhHH1Avn5npy3GV1Suin1Tyod3FP08TU= X-Virus-Scanned: amavisd-new at openmailbox.org Received: from mail2.openmailbox.org ([62.4.1.33]) by localhost (mail.openmailbox.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id s5GFDjOFdXKE; Sun, 10 May 2015 15:16:50 +0200 (CEST) Received: from www.openmailbox.org (mail2.openmailbox.org [62.4.1.33]) by mail2.openmailbox.org (Postfix) with ESMTP id 06397202D8F; Sun, 10 May 2015 15:16:49 +0200 (CEST) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Sun, 10 May 2015 18:46:49 +0530 From: Tinker To: Neel Natu Cc: freebsd-virtualization@freebsd.org Subject: Re: Is the BHyVe guest as suitable for high-performance disk IO as the =?UTF-8?Q?host=3F?= In-Reply-To: References: <7dd04a4cec612d18110a00b9020fd948@openmailbox.org> Message-ID: X-Sender: tinkr@openmailbox.org User-Agent: Roundcube Webmail/1.0.5 X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 10 May 2015 13:17:02 -0000 Hi Neel, Thank you very much for your response - That's great! I guess this should deliver the full capacity for basically any IO system around, be it a fast SSD or ramdisk. (Since the guest may not need to flush data immediately to the host, I guess read performance is the more sensitive point.) Which disk emulation mode is best for a BSD guest, "virtio-blk" or "ahci-hd"? In general, should any other consideration be made for performance (using the "direct" or "nocache" BHyVe configuration options, particular consideration for proper sector alignment when using a disk image stored on the host's SSD-based ZFS, mounting the host ZFS filesystem with "noatime")? Kind regards, Tinker On 2015-05-10 04:03, Neel Natu wrote: > Hi Tinker, > > On Sat, May 9, 2015 at 9:49 AM, Tinker wrote: >> Hi! >> >> For an environment with very heavy parallell IO, should the >> performance be >> just as good in a BHyVe guest as in the FreeBSD host environment? >> >> What I thought of is that I guess within the host environment, the >> storage >> subsystem should have all kinds of optimizations like an internal work >> queue >> that pushes lots of work alinearly/asynchronously to the disk >> controller and >> this way allows it, in turn, to give all its performance. >> >> Does the virtualized disk interface carry over all that goodness to >> the >> guest? >> > > bhyve creates 8 worker threads for each virtual disk controller (both > ahci and virtio-blk). > > All guest I/O is handled asynchronously by these worker threads which > provide parallelism. > >> (https://wiki.freebsd.org/bhyve seems to say yes, presuming you >> configure >> BHyVe to run the virtual disk in AHCI mode?) >> > > The wiki is out of date. > > Since r280037 the virtio-blk emulation also gets the benefits of using > the block_if worker threads. > > best > Neel > >> Thanks! >> Tinker >> >> _______________________________________________ >> freebsd-virtualization@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization >> To unsubscribe, send any mail to >> "freebsd-virtualization-unsubscribe@freebsd.org"