Re: [Xen-devel] [PATCH 2 of 2] libxc: Print domain ID in save restore messages

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On Fri, 2012-03-09 at 18:19 +0000, Ian Campbell wrote:
> On Fri, 2012-03-09 at 12:29 -0500, George Dunlap wrote:
> > XenServer redirects all libxc output to /var/log/messages, so when a
> > large stress test is running, it's hard to tell which message belongs
> > to which domain.
> > 
> > This patch adds the domain ID to output made by the save/restore
> > functions.
> > 
> > To do this, we introduce a layer of indirection in the libxc print
> > macros, so that they can be "interposed on" by individual functions.
> > 
> > We then add the domain ID to the context structs in the save and restore
> > paths, and replace the toplevel macros with ones which add the domain to the
> > output.
> > 
> > Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> > 
> > diff --git a/tools/libxc/xc_domain_restore.c 
> > b/tools/libxc/xc_domain_restore.c
> > --- a/tools/libxc/xc_domain_restore.c
> > +++ b/tools/libxc/xc_domain_restore.c
> > @@ -33,7 +33,20 @@
> >  #include <xen/hvm/ioreq.h>
> >  #include <xen/hvm/params.h>
> >  
> > +/* Override default output f'ns with functions that include the domain id 
> > */
> > +#undef IPRINTF
> > +#define IPRINTF(_F, _A...) _IPRINTF("d%d:" _F, ctx->dom, ## _A)
> 
> I think
> 
> #define DIPRINTF(_F, _A...) IPRINTF("d%s:" _F, ctx->dom, ## _A)
> 
> (or DOMIPRINTF etc) would end up looking nicer than these undef and the
> _IPRINTFs you've had to scatter around the place.

Perhaps; but that also requires that every person changing this file
forever more must remember to write "DIPRINTF" instead of "IPRINTF".
(And it requires me to change 10x as many LoC.)

 -George


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