Re: [Xen-devel] [PATCH v5 2/4] mm: modify domain_adjust_tot_pages() to better handle a zero adjustment

["Durrant, Paul" <pdurrant@xxxxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: 29 January 2020 11:13
> To: Durrant, Paul <pdurrant@xxxxxxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Andrew Cooper
> <andrew.cooper3@xxxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxxxxx>;
> Ian Jackson <ian.jackson@xxxxxxxxxxxxx>; Julien Grall <julien@xxxxxxx>;
> Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>; Stefano Stabellini
> <sstabellini@xxxxxxxxxx>; Wei Liu <wl@xxxxxxx>
> Subject: Re: [PATCH v5 2/4] mm: modify domain_adjust_tot_pages() to better
> handle a zero adjustment
> 
> On 29.01.2020 11:16, Paul Durrant wrote:
> > Currently the function will pointlessly acquire and release the global
> > 'heap_lock' in this case.
> >
> > NOTE: No caller yet calls domain_adjust_tot_pages() with a zero 'pages'
> >       argument, but a subsequent patch will make this possible.
> 
> With this memory_exchange(), as previously indicated, now needlessly
> prevents the call when !dec_count. I do think, as said there, that
> together with the addition here then redundant checks in callers
> should be dropped (and as it looks the named one is the only one).
> 

Ok, yes I missed that.

  Paul

> Jan
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