Re: [PATCH] memory: transaction API

[Avi Kivity <avi@redhat.com>]

On 07/21/2011 02:04 PM, Ferry Huberts wrote:
> On 07/21/2011 12:21 PM, Avi Kivity wrote:
> >  Allow changes to the memory hierarchy to be accumulated and
> >  made visible all at once.  This reduces computational effort,
> >  especially when an accelerator (e.g. kvm) is involved.
> >
> >  Useful when a single register update causes multiple changes
> >  to an address space.
> >
> >
> >  +void memory_region_transaction_begin(void)
> >  +{
> >  +    ++memory_region_transaction_depth;
> >  +}
> >  +
>
> wouldn't you rather keep it safe by doing either here
>
> if (!memory_region_transaction_depth)
>    memory_region_transaction_depth++;
>

Why? I want to allow nesting transactions (not that I anticipate such a 
case).

> >  +void memory_region_transaction_commit(void)
> >  +{
> >  +    if (!memory_region_transaction_depth) {
> >  +        abort();
> >  +    }
>
>
> >  +    --memory_region_transaction_depth;
> >  +    memory_region_update_topology();
> >  +}
> >  +
>
> or by doing here
>
> while (!memory_region_transaction_depth)
>    memory_region_transaction_depth--;
>
>
> with your setup nesting transactions will not work correctly I think.
> You seem to have designed it to not do nesting, so it's safer to make
> that explicit in your code imho

Nesting should work just fine.

> therefore I'd go for the change in _begin
>
> also, wouldn't you rather rename memory_region_transaction_depth to
> memory_region_transaction_pending?

The existing name works for me, but if people want it changed, that's 
fine too.


-- 
error compiling committee.c: too many arguments to function