Re: [PATCH 0/4] fix freemem loop

[Ian Campbell <ian.campbell@citrix.com>]

On Fri, 2015-03-06 at 09:48 +0000, Stefano Stabellini wrote:
> On Thu, 5 Mar 2015, Ian Campbell wrote:
> > On Tue, 2015-03-03 at 11:08 +0000, Stefano Stabellini wrote:
> > > Hi all,
> > > 
> > > this patch series fixes the freemem loop on machines with very large
> > > amount of memory, where the current wait time is not enough.
> > > 
> > > In order to be able to handle arbitrarly large amount of ram, we
> > > implement in libxl_wait_for_memory_target a policy of waiting until dom0
> > > is making progress.
> > 
> > What is the impact of the libxl API change made here on other callers,
> > in particular libvirt?
> > 
> > If it is expected that existing callers should continue to work as
> > before (perhaps with a redundant call etc) then please state this in the
> > relevant commit message(s).
> 
> The change to libxl_wait_for_memory_target will cause the function to
> wait as long as dom0 is ballooning down by any amount of memory in a 2
> seconds time frame. Therefore callers might end up waiting for longer
> than before, specifically longer than the amount of seconds they pass to
> libxl_wait_for_memory_target.
> 
> I'll add this message to the relevant commit.

Thanks. It might be worth waiting for Jim to say what the impact on new
libvirt (i.e. updated to take advantage of the fixed interface) built
against old libxl would be -- since we may want to include a #define
LIBXL_HAVE_SOMETHING in the resend.

> 
> 
> > >   The patch series also reverts "libxl: Wait for
> > > ballooning if free memory is increasing", that is not actually
> > > implemented correctly.
> > > 
> > > 
> > > Stefano Stabellini (4):
> > >       Revert "libxl: Wait for ballooning if free memory is increasing"
> > >       libxl_wait_for_memory_target: wait as long as dom0 is making progress
> > >       freemem: remove call to libxl_wait_for_free_memory
> > >       libxl_wait_for_memory_target: wait for 2 sec at a time
> > > 
> > >  tools/libxl/libxl.c      |   31 +++++++++++++++++++++++--------
> > >  tools/libxl/xl_cmdimpl.c |   29 ++++++-----------------------
> > >  2 files changed, 29 insertions(+), 31 deletions(-)
> > > 
> > > Cheers,
> > > 
> > > Stefano
> > 
> >