On 6/25/14 6:49 AM, Andriy Gapon wrote:
On 25/06/2014 17:44, Attilio Rao wrote:
Why? If VM needs more wired memory I assume that we can tune up the
default value of max_wired?
I think that however your case makes an interesting point: if we want
to make unmanaged pages as inherently wired, we likely need a little
bit higher max_wired value. When I completed a patch for this, pho@
couldn't reproduce any similar issue even with stress-testing (and
also, the places to allocate unmanaged pages and not requesting
VM_ALLOC_WIRED were very little, almost 0, with the exception of
vm_page_alloc_contig() calls) but I think it is a valid proposition.
However I would still like to have more control on kernel-specific
wired memory for processes. I'm for example thinking to ARC vs. buffer
cache, where I expect the wired memory consumption to be much bigger
for the former case.
My humble opinion is that userland page wiring should be tuned via
resource limits and that vm.max_wired could be retired altogether.
Kernel wiring ignores the knob anyway.
I think the goal of the limit as it stands would not to let the total
amount of wired pages reach a bad point due to a userland program
pushing it over the limit.
Basically userland wants to know how many pages the kernel has wired in
order to avoid asking for too many pages and making the system implode.
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