The hardware has dual quad core CPUs and 8GB RAM. It has only 1 domU. I want to configure the domU and let the domU has maximum performance. So I configure "vcpus=8" in the domU configure file. Is this right? Do I need to add any other directions? _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, 2009-10-14 at 11:33 +0800, Zu wrote:> The hardware has dual quad core CPUs and 8GB RAM. It has only 1 domU. > I want to configure the domU and let the domU has maximum performance. > So I configure "vcpus=8" in the domU configure file. Is this right? Do > I need to add any other directions?If it is the only domU on this server, is there any reason why you want it in xen? vcpus=8 is a good start, maybe give it maximum ram possible too. Have a look around to find instructions on setting the dom0 maximum memory and have it only use one of the cores to itself. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
I want to run cPanel on the domU. The domU cPanel license is cheap ( $15/month , http://www.buycpanel.com/ ) On Wed, Oct 14, 2009 at 1:03 PM, Tait Clarridge <tait@clarridge.ca> wrote:> On Wed, 2009-10-14 at 11:33 +0800, Zu wrote: >> The hardware has dual quad core CPUs and 8GB RAM. It has only 1 domU. >> I want to configure the domU and let the domU has maximum performance. >> So I configure "vcpus=8" in the domU configure file. Is this right? Do >> I need to add any other directions? > > > If it is the only domU on this server, is there any reason why you want > it in xen? vcpus=8 is a good start, maybe give it maximum ram possible > too. > > Have a look around to find instructions on setting the dom0 maximum > memory and have it only use one of the cores to itself. >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, Oct 14, 2009 at 10:33 AM, Zu <zuzhihui@gmail.com> wrote:> The hardware has dual quad core CPUs and 8GB RAM. It has only 1 domU. > I want to configure the domU and let the domU has maximum performance. > So I configure "vcpus=8" in the domU configure file. Is this right? Do > I need to add any other directions?assuming is doesn''t support hyperthreading (or hyperthreading disabled), I''d set it to 7 (i.e. 8-1). dom0 needs CPU as well you know, and it''s best to give dom0 a dedicated CPU/core. -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Tue, Oct 13, 2009 at 11:31 PM, Fajar A. Nugraha <fajar@fajar.net> wrote:> On Wed, Oct 14, 2009 at 10:33 AM, Zu <zuzhihui@gmail.com> wrote: >> The hardware has dual quad core CPUs and 8GB RAM. It has only 1 domU. >> I want to configure the domU and let the domU has maximum performance. >> So I configure "vcpus=8" in the domU configure file. Is this right? Do >> I need to add any other directions? > > assuming is doesn''t support hyperthreading (or hyperthreading > disabled), I''d set it to 7 (i.e. 8-1). dom0 needs CPU as well you > know, and it''s best to give dom0 a dedicated CPU/core. > > -- > Fajar >What if the dom0 has no tasks once the domU is up and running? eg: disable syslog, cron, etc on dom0 Can one assign all cores to the domU? Or, must one core remain idle dedicated to handling dom0 processing? -Bruce _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
CPU0 should stay behind to handle IO. Don''t disable syslog, etc. Best Regards, Nathan Eisenberg Sr. Systems Administrator - Atlas Networks, LLC office: 206.577.3078 | suncadia: 206.210.5450 www.atlasnetworks.us | www.suncadianet.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > What if the dom0 has no tasks once the domU is up and running? > eg: disable syslog, cron, etc on dom0 > Can one assign all cores to the domU? > Or, must one core remain idle dedicated to handling dom0 processing?Dom0 can share a core, but it''ll be timesliced if the dom0 has things to do. Which may not be good overall. I like to pin dom0 to one (or more) core, and leave everything else to domU. Whether this helps you or not depends on what the domU is doing. If your domU is compute-intensive, it may benefit from having access to all cores. But if it routinely does any block or network I/O, the dom0 needs to get involved, since that''s where the backend drivers usually run. And if dom0 has to wait for a CPU to become available, that may delay domU I/O. -Jeff _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thu, Oct 15, 2009 at 7:40 AM, Jeff Sturm <jeff.sturm@eprize.com> wrote:>> -----Original Message----- >> What if the dom0 has no tasks once the domU is up and running? >> eg: disable syslog, cron, etc on dom0 >> Can one assign all cores to the domU? >> Or, must one core remain idle dedicated to handling dom0 processing? > > Dom0 can share a core, but it''ll be timesliced if the dom0 has things to > do. Which may not be good overall. I like to pin dom0 to one (or more) > core, and leave everything else to domU. > > Whether this helps you or not depends on what the domU is doing. If > your domU is compute-intensive, it may benefit from having access to all > cores. But if it routinely does any block or network I/O, the dom0 > needs to get involved, since that''s where the backend drivers usually > run. And if dom0 has to wait for a CPU to become available, that may > delay domU I/O. > > -Jeff >This clarifies a lot, thanks Jeff. I''m not intentionally being thick, but I want to cover all possibilities :-) To extrapolate from that, if I wanted to avoid having dom0 competing for a core, I would have to pass through any devices the domU needed to access, or have hardware that supports sr-iov? Just for the sake of argument, if I could eliminate all hardware proxying requirements of the dom0, would a domU be able to hold on to all the cores, or would the dom0 or hypervisor still periodically "steal" a core? -Bruce _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > I''m not intentionally being thick, but I want to cover allpossibilities :-) No worries, I can appreciate wanting to know. Whenever I have the luxury of time, I like to experiment with settings I have not tried before, or to otherwise "push the envelope". I usually learn something new, useful or not...> To extrapolate from that, if I wanted to avoid having dom0 competing > for a core, I would have to pass through any devices the domU needed > to access, or have hardware that supports sr-iov?Yes, I think so. But I have no experience with this--I''ve used standard PV drivers for all my domU hosts.> Just for the sake of argument, if I could eliminate all hardware > proxying requirements of the dom0, would a domU be able to hold on to > all the cores, or would the dom0 or hypervisor still periodically > "steal" a core?Theoretically, if your domU were standalone and didn''t rely on dom0 for drivers or anything else, the dom0 could cease to operate entirely. Though I don''t know if that''s possible or practical with the Xen software as it is currently released. (Can you even pause a dom0? Never tried it...) As I understand Xen''s hypervisor architecture, a dom0 isn''t all that special, it''s just more privileged than any other domain. If a dom0 shuts down, I assume it must take down the hypervisor with it. But if the dom0 were just really, really quiet, there''s no reason I can think of that a domU can''t use most or all of the available hardware CPU resources. But keep in mind, as long as there is interrupt activity (e.g. timer0) there is at least some CPU activity on dom0. -Jeff _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users