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

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Mar 09, 2015 at 12:41:25PM +0000, Stefano Stabellini wrote:
> 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.
> 

Sorry, I missed that one. Adding the comment is enough.

Wei.

> > 
> > >  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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