On Wed, 10 Jun 2020 10:24:44 +0100 "Burakov, Anatoly" <anatoly.bura...@intel.com> wrote:
> On 09-Jun-20 4:35 PM, Stephen Hemminger wrote: > > On Tue, 9 Jun 2020 14:39:54 +0100 > > "Burakov, Anatoly" <anatoly.bura...@intel.com> wrote: > > > >> On 09-Jun-20 2:13 PM, Ferruh Yigit wrote: > >>> On 6/9/2020 1:46 PM, Burakov, Anatoly wrote: > >>>> On 08-Jun-20 12:03 PM, Francesco wrote: > >>>>> Hi all, > >>>>> I upgraded an old DPDK-based app which was using DPDK 17.11 to latest > >>>>> DPDK > >>>>> 20.05 and I noticed that if I look at "top" I see that the VIRT memory > >>>>> taken by my application is now 256.1GB while before it was <1GB. > >>>>> > >>>>> I've seen this same behavior with also "testpmd" example... is this a > >>>>> known > >>>>> issue with latest DPDK versions? > >>>>> Can I tweak some setting to have VIRT memory usage more or less similar > >>>>> to > >>>>> RSS ? > >>>>> > >>>>> I forgot to add I'm working on Linux, Centos7 > >>>>> > >>>>> Thanks, > >>>>> Francesco Montorsi > >>>>> > >>>> > >>>> There was a discussion on this not too long ago, but i can't seem to > >>>> find it for some reason. > >>> > >>> Can it be "Big spike in DPDK VSZ" ? > >>> http://inbox.dpdk.org/dev/CAGxAMwD6Wtfi=C2Txwjfk0zhFvRzeqBu7mFfE8ayh=eji2a...@mail.gmail.com/#t > >>> > >> > >> Yes, that's the one, thanks Ferruh :) > >> > >>>> Anyway, long story short, that's not a bug, > >>>> that's by design. > >>>> > >>>> Since 18.11 (or 18.05 to be precise), there is a new memory subsystem in > >>>> DPDK that allows growing and shrinking DPDK memory usage at runtime. > >>>> That means, you can start with zero hugepages preallocated, and then > >>>> allocate as you go, letting the memory subsystem decide how much memory > >>>> you need. > >>>> > >>>> The catch is that all of this hugepage memory is allocated into > >>>> somewhere, some virtual address space. And *that* address space is > >>>> preallocated at startup, to allow for secondary processes to duplicate > >>>> primary process's address space exactly, and allow dynamic allocation of > >>>> *shared* memory at runtime. > >>>> > >>>> This memory will show up in top et al. but the truth is, it's zero cost, > >>>> because it's anonymous memory. It isn't actually taking up any RAM. It > >>>> will show up in dumps (20.05 has already fixed that issue, and the fixes > >>>> will probably be backported to stable, including 18.11), so unless you > >>>> have a very specific problem, i don't think that's anything you should > >>>> be concerned about. > > > > The one concern is for cases like cgroup memory accounting thinking > > the process is huge and OOM killing it. > > > > Is there any way to know the *actual* memory usage of the process (i.e. > not including anonymous memory)? > Huge pages do not count against the normal memory in cgroup. There is a separate hugeTLB controller that limits that.
