> -----Original Message----- > From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx] > Sent: Sunday, March 03, 2013 9:08 PM > To: KY Srinivasan > Cc: linux-kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; olaf@xxxxxxxxx; > apw@xxxxxxxxxxxxx; andi@xxxxxxxxxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; linux- > mm@xxxxxxxxx > Subject: Re: [PATCH 1/1] mm: Export split_page(). > > On Sun, Mar 03, 2013 at 06:27:55PM -0800, K. Y. Srinivasan wrote: > > The split_page() function will be very useful for balloon drivers. On Hyper-V, > > it will be very efficient to use 2M allocations in the guest as this (a) makes > > the ballooning protocol with the host that much more efficient and (b) moving > > memory in 2M chunks minimizes fragmentation in the host. Export the > split_page() > > function to let the guest allocations be in 2M chunks while the host is free to > > return this memory at arbitrary granularity. > > > > > > Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > > --- > > mm/page_alloc.c | 1 + > > 1 files changed, 1 insertions(+), 0 deletions(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 6cacfee..7e0ead6 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1404,6 +1404,7 @@ void split_page(struct page *page, unsigned int order) > > for (i = 1; i < (1 << order); i++) > > set_page_refcounted(page + i); > > } > > +EXPORT_SYMBOL_GPL(split_page); > > When you export a symbol, you also need to post the code that is going > to use that symbol, otherwise people don't really know how to judge this > request. > > Can you just make this a part of your balloon driver update patch series > instead? Fair enough; I was hoping to see how inclined the mm folks were with regards to exporting this symbol before I went ahead and modified the balloon driver code to leverage this. Looking at the Windows guests on Hyper-V, I am convinced 2M balloon allocations in the Linux (Hyper-V) balloon driver will make significant difference. As you suggest, I will post this patch as part of the balloon driver changes that use this exported symbol. I am still hoping to get some feedback from the mm guys on this. Regards, K. Y _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
