From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755768AbeDXFXC (ORCPT ); Tue, 24 Apr 2018 01:23:02 -0400 Received: from mx2.suse.de ([195.135.220.15]:43503 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751603AbeDXFXA (ORCPT ); Tue, 24 Apr 2018 01:23:00 -0400 Subject: Re: [Xen-devel] [RFC 0/2] To introduce xenwatch multithreading (xen mtwatch) To: Dongli Zhang , Wei Liu Cc: ian.jackson@eu.citrix.com, linux-kernel@vger.kernel.org, srinivas.eeda@oracle.com, xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com, Joao Martins References: <1523100355-27647-1-git-send-email-dongli.zhang@oracle.com> <20180423140911.bihiwfwtlneobgzd@citrix.com> <6c379249-886d-76ee-db9c-942967b23d80@oracle.com> From: Juergen Gross Message-ID: Date: Tue, 24 Apr 2018 07:22:56 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <6c379249-886d-76ee-db9c-942967b23d80@oracle.com> Content-Type: text/plain; charset=windows-1252 Content-Language: de-DE Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/04/18 01:55, Dongli Zhang wrote: > Hi Wei, > > On 04/23/2018 10:09 PM, Wei Liu wrote: >> On Sat, Apr 07, 2018 at 07:25:53PM +0800, Dongli Zhang wrote: >>> About per-domU xenwatch thread create/destroy, a new type of xenstore node is >>> introduced: '/local/domain/0/mtwatch/'. >>> >>> Suppose the new domid id 7. During the domU (domid=7) creation, the xen >>> toolstack writes '/local/domain/0/mtwatch/7' to xenstore before the insertion >>> of '/local/domain/7'. When the domid=7 is destroyed, the last xenstore >>> operation by xen toolstack is to remove '/local/domain/0/mtwatch/7'. >>> >>> The dom0 kernel subscribes a watch at node '/local/domain/0/mtwatch'. Kernel >>> thread [xen-mtwatch-7] is created when '/local/domain/0/mtwatch/7' is inserted, >>> while this kernel thread is destroyed when the corresponding xenstore node is >>> removed. >> >> Instead of inventing yet another node, can you not watch /local/domain >> directly? > > Would you like to watch at /local/domain directly? Or is your question "is there > any other way to not watch at /local/domain, while no extra xenstore node will > be introduced"? > > Actually, the first prototype of this idea was to watch at /local/domain > directly to get aware of the domU create/destroy, so that xen toolstack will not > get involved. Joao Martins (CCed) had a concern on the performance as watching > at /local/domain would lead to large amount of xenwatch events. That's what the special watches "@introduceDomain" and "@releaseDomain" are meant for. Juergen