Hi all,
I have just noticed that the timer mode default in libxl is not the
default in Xen.
The Xen default is HVMPTM_delay_for_missed_ticks, while libxl by
default sets it to LIBXL_TIMER_MODE_NO_DELAY_FOR_MISSED_TICKS that
obviously is HVMPTM_no_delay_for_missed_ticks.
Is there a reason for this?
If so, should we change the defalt in Xen too?
commit 2d058a444a1fa71ec47a673d08c2e74790ae67fb
Author: Ian Campbell <ian.campbell@citrix.com>
Date: Thu Mar 1 12:26:13 2012 +0000
libxl: use an explicit LIBXL_TIMER_MODE_DEFAULT value
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
On 25/04/2013 18:13, "Stefano Stabellini" <stefano.stabellini@eu.citrix.com> wrote:> Hi all, > I have just noticed that the timer mode default in libxl is not the > default in Xen. > The Xen default is HVMPTM_delay_for_missed_ticks, while libxl by > default sets it to LIBXL_TIMER_MODE_NO_DELAY_FOR_MISSED_TICKS that > obviously is HVMPTM_no_delay_for_missed_ticks. > > Is there a reason for this? > If so, should we change the defalt in Xen too?Default in Xen is the original mode before multiple modes were supported. We kept that as default for old/other toolstacks, to avoid surprising change in behaviour (e.g., when they restore old saved guests). Default in libxl is the sane one for newly-created guests. Hardly any guests care about or even want time to be delayed until timer interrupts are fired off. -- Keir> commit 2d058a444a1fa71ec47a673d08c2e74790ae67fb > Author: Ian Campbell <ian.campbell@citrix.com> > Date: Thu Mar 1 12:26:13 2012 +0000 > > libxl: use an explicit LIBXL_TIMER_MODE_DEFAULT value > > Signed-off-by: Ian Campbell <ian.campbell@citrix.com> > Acked-by: Ian Jackson <ian.jackson@eu.citrix.com> > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel
On Thu, 2013-04-25 at 18:13 +0100, Stefano Stabellini wrote:> Hi all, > I have just noticed that the timer mode default in libxl is not the > default in Xen. > The Xen default is HVMPTM_delay_for_missed_ticks, while libxl by > default sets it to LIBXL_TIMER_MODE_NO_DELAY_FOR_MISSED_TICKS that > obviously is HVMPTM_no_delay_for_missed_ticks. > > Is there a reason for this? > If so, should we change the defalt in Xen too? > > commit 2d058a444a1fa71ec47a673d08c2e74790ae67fb > Author: Ian Campbell <ian.campbell@citrix.com> > Date: Thu Mar 1 12:26:13 2012 +0000 > > libxl: use an explicit LIBXL_TIMER_MODE_DEFAULT value > > Signed-off-by: Ian Campbell <ian.campbell@citrix.com>This commit just changed the way the default was set, but it didn''t change that default. Tracking back through the history it seems the original change was: commit 85bd32d9085828dcfa29215c78d472afa0cfd3ad Author: Ian Jackson <Ian.Jackson@eu.citrix.com> Date: Wed Jul 14 16:31:59 2010 +0100 xl: default timer_mode to 1 Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c index e7aa89b..9706a6a 100644 --- a/tools/libxl/xl_cmdimpl.c +++ b/tools/libxl/xl_cmdimpl.c @@ -205,7 +205,7 @@ static void init_build_info(libxl_domain_build_info *b_info, libxl_domain_create b_info->u.hvm.viridian = 0; b_info->u.hvm.hpet = 1; b_info->u.hvm.vpt_align = 1; - b_info->u.hvm.timer_mode = 0; + b_info->u.hvm.timer_mode = 1; } else { b_info->u.pv.slack_memkb = 8 * 1024; } So you tell us ;-) (you see now why I''m picky about changelogs...)
On Fri, 26 Apr 2013, Ian Campbell wrote:> On Thu, 2013-04-25 at 18:13 +0100, Stefano Stabellini wrote: > > Hi all, > > I have just noticed that the timer mode default in libxl is not the > > default in Xen. > > The Xen default is HVMPTM_delay_for_missed_ticks, while libxl by > > default sets it to LIBXL_TIMER_MODE_NO_DELAY_FOR_MISSED_TICKS that > > obviously is HVMPTM_no_delay_for_missed_ticks. > > > > Is there a reason for this? > > If so, should we change the defalt in Xen too? > > > > commit 2d058a444a1fa71ec47a673d08c2e74790ae67fb > > Author: Ian Campbell <ian.campbell@citrix.com> > > Date: Thu Mar 1 12:26:13 2012 +0000 > > > > libxl: use an explicit LIBXL_TIMER_MODE_DEFAULT value > > > > Signed-off-by: Ian Campbell <ian.campbell@citrix.com> > > This commit just changed the way the default was set, but it didn''t > change that default. Tracking back through the history it seems the > original change was: > > commit 85bd32d9085828dcfa29215c78d472afa0cfd3ad > Author: Ian Jackson <Ian.Jackson@eu.citrix.com> > Date: Wed Jul 14 16:31:59 2010 +0100 > > xl: default timer_mode to 1 > > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c > index e7aa89b..9706a6a 100644 > --- a/tools/libxl/xl_cmdimpl.c > +++ b/tools/libxl/xl_cmdimpl.c > @@ -205,7 +205,7 @@ static void init_build_info(libxl_domain_build_info *b_info, libxl_domain_create > b_info->u.hvm.viridian = 0; > b_info->u.hvm.hpet = 1; > b_info->u.hvm.vpt_align = 1; > - b_info->u.hvm.timer_mode = 0; > + b_info->u.hvm.timer_mode = 1; > } else { > b_info->u.pv.slack_memkb = 8 * 1024; > } > > So you tell us ;-) (you see now why I''m picky about changelogs...)LOL It must have been to match the default in xend.