Martinx - ジェームズ
2010-Mar-17 17:10 UTC
[Xen-users] Linux CONFIG_HZ_100=y or CONFIG_HZ_1000=y for Xen dom0/domUs?
Hi! The kernel shipped by Citrix for Debian via xen-tools are configured with CONFIG_HZ_100=y, but the Debian kernels and my custom kernels are configured for CONFIG_HZ_250=y or even CONFIG_HZ_1000=y. So, what is the impact of this clock to a Xen system? Which option is more suitable for Xen systems? Regards, Thiago _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Pasi Kärkkäinen
2010-Mar-18 19:23 UTC
Re: [Xen-users] Linux CONFIG_HZ_100=y or CONFIG_HZ_1000=y for Xen dom0/domUs?
On Wed, Mar 17, 2010 at 02:10:11PM -0300, Martinx - ?$B%8%''!<%`%: wrote:> Hi! > > The kernel shipped by Citrix for Debian via xen-tools are configured with > CONFIG_HZ_100=y, but the Debian kernels and my custom kernels are > configured for CONFIG_HZ_250=y or even CONFIG_HZ_1000=y. > > So, what is the impact of this clock to a Xen system? > > Which option is more suitable for Xen systems? >This is really common for all virtualized environments, so it also applies to VMware etc. Your _guest_ kernel should have HZ=100 rather than HZ=1000. HZ=100 will use a lot less CPU time when the guest is idle. -- Pasi _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Martinx - ジェームズ
2010-Mar-18 19:47 UTC
Re: [Xen-users] Linux CONFIG_HZ_100=y or CONFIG_HZ_1000=y for Xen dom0/domUs?
Gotcha! But, the dom0 Linux should be 1000 or 100? On 18 March 2010 16:23, Pasi Kärkkäinen <pasik@iki.fi> wrote:> On Wed, Mar 17, 2010 at 02:10:11PM -0300, Martinx - ?$B%8%''!<%`%: wrote: > > Hi! > > > > The kernel shipped by Citrix for Debian via xen-tools are configured > with > > CONFIG_HZ_100=y, but the Debian kernels and my custom kernels are > > configured for CONFIG_HZ_250=y or even CONFIG_HZ_1000=y. > > > > So, what is the impact of this clock to a Xen system? > > > > Which option is more suitable for Xen systems? > > > > This is really common for all virtualized environments, so it also applies > to VMware etc. > > Your _guest_ kernel should have HZ=100 rather than HZ=1000. HZ=100 will use > a lot less CPU time when the guest is idle. > > -- Pasi > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users