Hi, Thanks for the clarification
Regards, Siddarth On Tue, Feb 4, 2020 at 4:43 PM Burakov, Anatoly <anatoly.bura...@intel.com> wrote: > On 04-Feb-20 10:55 AM, siddarth rai wrote: > > Hi Anatoly, > > > > I don't need a secondary process. > > I understand that you don't, however that doesn't negate the fact that > the codepath expects that you do. > > > > > I tried out Julien's suggestion and set the param 'RTE_MAX_MEM_MB' value > > to 8192 (the original value was over 500K). This works as a cap. > > The virtual size dropped down to less than 8G. So this seems to be > > working for me. > > > > I have a few queries/concerns though. > > Is it safe to reduce the RTE_MAX_MEM_MB to such a low value ? Can I > > reduce it further ? What will be the impact of doing so ? Will it limit > > the maximum size of mbuf pool which I create ? > > It depends on your use case. The maximum size of mempool is limited as > is, the better question is where to place that limit. In my experience, > testpmd mempools are typically around 400MB per socket, so an 8G upper > limit should not interfere with testpmd very much. However, depending on > what else is there and what kind of allocations you may do, it may have > other effects. > > Currently, the size of each internal per-NUMA node, per-page size page > table is dictated by three constraints: maximum amount of memory per > page table (so that we don't attempt to reserve thousands of 1G pages), > maximum number of pages per page table (so that we aren't left with a > few hundred megabytes' worth of 2M pages), and total maximum amount of > memory (which places an upper limit on the sum of all page tables' > memory amounts). > > You have lowered the latter to 8G which means that, depending on your > system configuration, you will have at most 2G to 4G per page table. It > is not possible to limit it further (for example, skip reservation on > certain nodes or certain page sizes). Whether it will have an effect on > your actual workload will depend on your use case. > > > > > Regards, > > Siddarth > > > > On Tue, Feb 4, 2020 at 3:53 PM Burakov, Anatoly > > <anatoly.bura...@intel.com <mailto: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 > > <mailto: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 :) > > > > > > > > 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 :) > > > > > > > > > > > > > > -- > > > David Marchand > > > > > > > > > -- > > Thanks, > > Anatoly > > > > > -- > Thanks, > Anatoly >
