On 11-Feb-20 8:11 AM, David Marchand wrote:
Hello Anatoly,
On Tue, Feb 4, 2020 at 11:23 AM Burakov, Anatoly
<anatoly.bura...@intel.com> wrote:
On 30-Jan-20 8:51 AM, David Marchand wrote:
On Thu, Jan 30, 2020 at 8:48 AM siddarth rai <sid...@gmail.com> wrote:
I have been using DPDK 19.08 and I notice the process VSZ is huge.
I tried running the test PMD. It takes 64G VSZ and if I use the
'--in-memory' option it takes up to 188G.
Is there anyway to disable allocation of such huge VSZ in DPDK ?
*Disclaimer* I don't know the arcanes of the mem subsystem.
I suppose this is due to the memory allocator in dpdk that reserves
unused virtual space (for memory hotplug + multiprocess).
Yes, that's correct. In order to guarantee memory reservation succeeding
at all times, we need to reserve all possible memory in advance.
Otherwise we may end up in a situation where primary process has
allocated a page, but the secondary can't map it because the address
space is already occupied by something else.
If this is the case, maybe we could do something to enhance the
situation for applications that won't care about multiprocess.
Like inform dpdk that the application won't use multiprocess and skip
those reservations.
You're welcome to try this, but i assure you, avoiding these
reservations is a lot of work, because you'd be adding a yet another
path to an already overly complex allocator :)
Went and looked at the EAL options we have.
I understand that the --in-memory (essentially the --no-shconf
functionality) option should be enough.
I can see that Siddarth uses it.
But the problem is that the memory allocator still reserves big va
areas for memory hotplug.
Yes, because even though we don't *share* this memory, we still grow it
dynamically. We could have *not* done it, but that would be adding
another code path - currently, we're piggybacking off existing
infrastructure.
Or another idea would be to limit those reservations to what is passed
via --socket-limit.
Anatoly?
I have a patchset in the works that does this and was planning to submit
it to 19.08, but things got in the way and it's still sitting there
collecting bit rot. This may be reason enough to resurrect it and finish
it up :)
Does this patchset contain more than just taking --socket-limit into account?
No, it actually doesn't rely on any of the existing options. It has to
do with tweaking the config options related to memseg list sizings
(essentially like adjusting config options at compile time, only without
hardcoding them).
--
David Marchand
--
Thanks,
Anatoly
