Thanks for the answers Avi, Juan, Some FYI, (not about the bottleneck) On Wed, 01 Dec 2010 14:35:57 +0200 Avi Kivity <avi@xxxxxxxxxx> wrote: > > > - how many dirty pages do we have to care? > > > > default values and assuming 1Gigabit ethernet for ourselves ~9.5MB of > > dirty pages to have only 30ms of downtime. > > 1Gb/s * 30ms = 100 MB/s * 30 ms = 3 MB. > 3MB / 4KB/page = 750 pages. Then, KVM side processing is near the theoretical goal! In my framebuffer test, I tested nr_dirty_pages/npages = 576/4096 case with the rate of 20 updates/s (1updates/50ms). Using rmap optimization, write protection only took 46,718 tsc time. Bitmap copy was not a problem of course. The display was working anyway at this rate! In my guess, within 1,000 dirty pages, kvm_vm_ioctl_get_dirty_log() can be processed within 200us or so even for large RAM slot. - rmap optimization depends mainly on nr_dirty_pages but npages. Avi, can you guess the property of O(1) write protection? I want to test rmap optimization taking these issues into acount. Of course, Kemari have to continue synchronization, and maybe see more dirty pages. This will be a future task! Thanks, Takuya -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
