search for: pfn_4g

The current QEMU live migration implementation mark the all the guest's RAM pages as dirtied in the ram bulk stage, all these pages will be processed and that takes quit a lot of CPU cycles. >From guest's point of view, it doesn't care about the content in free pages. We can make use of this fact and skip processing the free pages in the ram bulk stage, it can save a lot CPU cycles

The current QEMU live migration implementation mark the all the guest's RAM pages as dirtied in the ram bulk stage, all these pages will be processed and that takes quit a lot of CPU cycles. >From guest's point of view, it doesn't care about the content in free pages. We can make use of this fact and skip processing the free pages in the ram bulk stage, it can save a lot CPU cycles

...+ spin_lock_irqsave(&zone->lock, flags); + + for_each_migratetype_order(order, t) { + list_for_each(curr, &zone->free_area[order].free_list[t]) { + + pfn = page_to_pfn(list_entry(curr, struct page, lru)); + for (i = 0; i < (1UL << order); i++) { + if ((pfn + i) >= PFN_4G) + set_bit_le(pfn + i - pfn_gap, + free_page_bitmap); + else + set_bit_le(pfn + i, free_page_bitmap); + } + } + } + + spin_unlock_irqrestore(&zone->lock, flags); } ---------------------------------------------------- Sorry for my poor English and expression, if you stil...

...+ spin_lock_irqsave(&zone->lock, flags); + + for_each_migratetype_order(order, t) { + list_for_each(curr, &zone->free_area[order].free_list[t]) { + + pfn = page_to_pfn(list_entry(curr, struct page, lru)); + for (i = 0; i < (1UL << order); i++) { + if ((pfn + i) >= PFN_4G) + set_bit_le(pfn + i - pfn_gap, + free_page_bitmap); + else + set_bit_le(pfn + i, free_page_bitmap); + } + } + } + + spin_unlock_irqrestore(&zone->lock, flags); } ---------------------------------------------------- Sorry for my poor English and expression, if you stil...

...lock, flags); > + > + for_each_migratetype_order(order, t) { > + list_for_each(curr, &zone->free_area[order].free_list[t]) { > + > + pfn = page_to_pfn(list_entry(curr, struct page, lru)); > + for (i = 0; i < (1UL << order); i++) { > + if ((pfn + i) >= PFN_4G) > + set_bit_le(pfn + i - pfn_gap, > + free_page_bitmap); > + else > + set_bit_le(pfn + i, free_page_bitmap); > + } > + } > + } > + > + spin_unlock_irqrestore(&zone->lock, flags); } > ---------------------------------------------------- &gt...

> On Fri, Mar 04, 2016 at 09:12:12AM +0000, Li, Liang Z wrote: > > > Although I wonder which is cheaper; that would be fairly expensive > > > for the guest wouldn't it? And you'd somehow have to kick the guest > > > before migration to do the ballooning - and how long would you wait for > it to finish? > > > > About 5 seconds for an 8G guest,

> On Fri, Mar 04, 2016 at 09:12:12AM +0000, Li, Liang Z wrote: > > > Although I wonder which is cheaper; that would be fairly expensive > > > for the guest wouldn't it? And you'd somehow have to kick the guest > > > before migration to do the ballooning - and how long would you wait for > it to finish? > > > > About 5 seconds for an 8G guest,