Re: [Qemu-devel] [Bug 1100843] Re: Live Migration Causes Performance Issues

[Peter Lieven]

On 07.10.2013 11:55, Paolo Bonzini wrote:
> Il 07/10/2013 11:49, Peter Lieven ha scritto:
> > > It's in general not easy to do this if you take non-x86 targets into
> > > account.
> > What about the dirty way to zero out all non zero pages at the beginning of
> > ram_load?
> I'm not sure I follow?
sth like this for each ram block at the beginning of ram_load.

 
+                    base = memory_region_get_ram_ptr(block->mr);
+                    for (offset = 0; offset < block->length;
+                         offset += TARGET_PAGE_SIZE) {
+                        if (!is_zero_page(base + offset)) {
+                            memset(base + offset, 0x00, TARGET_PAGE_SIZE);
+                        }
+                    }
+

Then add a capability "skip_zero_pages" which does not sent them on the source
and enables this zeroing. it would also be possible to skip the zero check
for each incoming compressed pages.

Peter