> -----Original Message-----
> From: Dave Hansen [mailto:d...@sr71.net]
> Sent: Wednesday, July 24, 2013 5:04 PM
> To: KY Srinivasan
> Cc: gre...@linuxfoundation.org; linux-ker...@vger.kernel.org;
> de...@linuxdriverproject.org; o...@aepfle.de; a...@canonical.com;
> a...@firstfloor.org; a...@linux-foundation.org; linux...@kvack.org;
> kamezawa.hiroy...@gmail.com; mho...@suse.cz; han...@cmpxchg.org;
> ying...@google.com
> Subject: Re: [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in
> context"
> 
> On 07/24/2013 02:29 PM, K. Y. Srinivasan wrote:
> >             /*
> > -            * Wait for the memory block to be onlined.
> > -            * Since the hot add has succeeded, it is ok to
> > -            * proceed even if the pages in the hot added region
> > -            * have not been "onlined" within the allowed time.
> > +            * Before proceeding to hot add the next segment,
> > +            * online the segment that has been hot added.
> >              */
> > -           wait_for_completion_timeout(&dm_device.ol_waitevent,
> 5*HZ);
> > +           online_memory_block(start_pfn);
> 
> Ahhhhh....  You've got a timeout in the code in order to tell the
> hypervisor that you were successfully able to add the memory?  The
> userspace addition code probably wasn't running within this timeout
> period.  right?

As I have always said, the onlining would not occur within a specified amount
of time (under some conditions). The timeout here is to ensure that we are able 
to online the memory before attempting to hot-add more memory. With the ability
to online memory from within the kernel, we don't need this timeout and the 
code is
much more predictable.

Regards,

K. Y



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