Re: [libvirt] [PATCH] qemu: process: Fix automatic setting of locked memory limit for VFIO

On Thu, Nov 05, 2015 at 08:41:46 -0700, Alex Williamson wrote: [...] Okay, that seems reasonable. I'll extract the code that sets the limit into a helper, so that there's a central point where this stuff can be tweaked and made machine dependent. As of the x86 lock limit. Currently the code states the following: /* VFIO requires all of the guest's memory to be * locked resident, plus some amount for IO * space. Alex Williamson suggested adding 1GiB for IO * space just to be safe (some finer tuning might be * nice, though). */ Disregarding the empirical evidence that this worked until now on x86 the comment's message here is rather unsure about the actual size used at this point and hints it might need tweaking. If I'm going to move this I'd really like to remove the uncertainity from the message. So will I be able to justify: - dropping "some" from some ammount for IO space - replacing "Alex Williamson suggested adding" by something more scientifical I think the mlock size will be justified far more with comment like: /* VFIO requires all of guest's memory and memory for the IO space to * be locked persistent. * * On x86 the IO space size is 1GiB. * [some lines for possibly other platforms] */ Is it valid to make such change or do we need to keep the ambiguity and just reference the empirical fact that it didn't break yet? Peter