>> Are every guest pages scanned in KVM while using KSM or page-scanning >> and sharing is triggered on some event (low memory, etc) ? >> > > no, the scanning run all the time (with number pages to scan and sleep > parameters...)
Does the scanner(s) run as separate kernel threads ? >> Is sharing done only between the pages which have been registered via >> KSM_REGISTER_MEMORY_REGION ? >> > > yes > >> What are these for ? KSM_CREATE_SHARED_MEMORY_AREA and KSM_CREATE_SCAN ? >> > > KSM_CREATE_SHARED_MEMORY_AREA - to register memory area to be scanned for > identical pages > KSM_CREATE_SCAN - to create the scanner that scan for this pages So kvm will create a scanner using KSM_CREATE_SCAN ioctl to /dev/ksm. kvm sets its parameters which specify the frequency of scan operation. Then, it tries to determine periodically from the shadow page tables about the guest memory region, and registers them with the /dev/ksm. The scanner as configured will scan the registered areas and will create COW shared pages for identical pages. Am I right ? Doesn't KSM notifies KVM about the shared pages so that KVM can update its sptes accordingly or is it done by KSM itself ? What about KSM being used by someone other than KVM ? Does KSM updates the ptes of the shared pages itself ? >> Where are the shared pages kept ? In kernel memory ? Aren't the shared >> pages always pinned in RAM (due to same reasons for pinned shadowed >> pages) ? >> > > in the version that was sent to the list it was kernel memory (meaning > shared pages are not swappable > (just the pages that are shared not the pages that we scan, when they are > split beacuse of copy on write it become swappable again > new version that i will send soon the pages are normal anonymous/userspace > memory that is swappable > What is the strategy/method which you will use to represent the shared memory as normal anonymous/userspace memory ? Then, these pages must be staying at one of the guest's address-space (whose pages have been shared) ? >> How much is the overhead involved due to this ? >> > > depeand on the speed you tell it to scan, but the overhead is about ~5% for > common cases Can I know the typical values of the parameters : sleep time, no. of pages to scan, which you used to arrive at the above mentioned overhead. -- Regards, Sukanto Ghosh -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
