> But another view to the swap problem - or should we say the problem of > sharing real memory: > Can't we live without swap at all and use the cooperative memory management > technique? > You just define enough real memory for each linux instance to handle every > peak (well, maybe almost) > and they just use what they really need and release everything else to the > common memory pool. > You don't have to save free memory for new linux instances - all the memory > which is free above VM > for linuxes can be defined for them and they share it dynamically in the most > effective way.
This is essentially how the x86 virtualisation systems work. Pages are "stolen" from one guest and handed to another. You still need swap because you simply can't predict or guarantee that someone won't load all the guests up at the same moment, but you can make better use of free memory. The actual implementation used is to allocate memory in a guest which has excess memory and in effect loan it to another guest based upon memory pressure. As operating systems already allow the device drivers and kernel to allocate memory, it turns out a model where each kernel appears to allocate memory and sit on it (in fact loaning it to another guest) keeps the changes to the guest OS as small as possible. Alan ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
