On Wed, 6 Nov, 2019, 5:46 pm Burakov, Anatoly, <anatoly.bura...@intel.com> wrote:
> On 04-Nov-19 12:59 PM, Jerin Jacob Kollanukkaran wrote: > > Hi Anatoly and All, > > > > Just wondering what would the side effect of lowering a _bit_ of static > uint64_t baseaddr = 0x100000000 in > > lib/librte_eal/common/eal_common_memory.c for 64bit systems. > > > > Use case: > > If we _reserve_ VA address which less than 2^32 ONLY for packet > buffers(mbuf), The use cases like > > Pipeline, where need to transfer packets from one core to another cores > can use ring element > > size of 4B(32bit) which will reduce the a lot of read and write to > enable better > > performance. > > > > i.e Since upper 32bits will be zero, it is matter of typecasting of item > to read and write from/to ring. > > Essentially memcpy overhead for moving pointers over the ring will be > half. > > > > Is baseaddr set to 2^32 to make sure that secondary process will have > more _chance_ of getting > > the baseaddr in order for DPDK to work? > > > > Thoughts on above? On general to reduce the mbuf pointer storage > requirement for ring? > > > > You can already try that with --base-virtaddr option if you have such > specific addressing requirements. That said, the address is pretty much > arbitrary, so i'm not against lowering it in principle, it just feels > like a workaround for something that's very specific to the workloads > you are targetting. > Thanks for the feedback. I will find the performance delta first to decide any such option makes sense. > -- > Thanks, > Anatoly >
