Re: [Xen-devel] [PATCH v2 2/4] libxl_wait_for_memory_target: wait as long as dom0 is making progress

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 9 Mar 2015, Wei Liu wrote:
> On Fri, Mar 06, 2015 at 05:19:15PM +0000, Stefano Stabellini wrote:
> [...]
> >  int libxl_wait_for_free_memory(libxl_ctx *ctx, uint32_t domid, uint32_t 
> > memory_kb, int wait_secs);
> > -/* wait for the memory target of a domain to be reached */
> > +/* 
> > + * Wait for the memory target of a domain to be reached. Does not
> > + * decrement wait_secs if the domain is making progress toward reaching
> > + * the target. If the domain is not making progress, wait_secs is
> > + * decremented. If the timeout expires before the target is reached, the
> > + * function returns ERROR_FAIL.
> > + *
> > + * Older versions of this function (Xen 4.5 and older), decremented
> > + * wait_secs even if the domain was making progress, resulting in far
> > + * lower overall wait times. To make sure that your calling routine
> > + * works with new and old implementations of the function, pass enough
> > + * time for the guest to reach its target as an argument.
> > + */
> 
> Need to have a #define LIBXL_HAVE_$FOO to mark the change in behaviour,
> so that client can cope with this change.
> 

Given the very limited change in behaviour (in fact existing callers
should work as-is) I thought that we could do without one. Also see:
http://marc.info/?l=xen-devel&m=142563879603876&w=2.

> 
> >  int libxl_wait_for_memory_target(libxl_ctx *ctx, uint32_t domid, int 
> > wait_secs);
> >  
> >  int libxl_vncviewer_exec(libxl_ctx *ctx, uint32_t domid, int autopass);
> > diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
> > index f4c4122..2dc7574 100644
> > --- a/tools/libxl/xl_cmdimpl.c
> > +++ b/tools/libxl/xl_cmdimpl.c
> > @@ -2226,8 +2226,8 @@ static int freemem(uint32_t domid, 
> > libxl_domain_build_info *b_info)
> >          else if (rc != ERROR_NOMEM)
> >              return rc;
> >  
> > -        /* the memory target has been reached but the free memory is still
> > -         * not enough: loop over again */
> > +        /* wait until dom0 reaches its target, as long as we are making
> > +         * progress */
> >          rc = libxl_wait_for_memory_target(ctx, 0, 1);
> >          if (rc < 0)
> >              return rc;
> > -- 
> > 1.7.10.4
> 

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