Hello, I am currently evaluating various 0-copy packet capture frameworks on Linux. One of them is packet mmap, provided by the mainline Linux kernel.
I want to capture on one network interface with several raw sockets, each being used in a dedicated thread (to spread the processing load on several cores). My first test program works well, however I am now trying to gain even more performance by mapping RX rings inside 1GB huge pages (other 0-copy network frameworks like DPDK do this). My first question is: is it possible to map the rx ring of packet_mmap using huge pages, with the current Linux kernel? If it is possible, what specific flags must be passed to mmap? Here is what I tried so far: * Calling mmap on the socket file descriptor (to set the rx ring address) with MAP_SHARED | MAP_HUGETLB | MAP_HUGE_1GB => mmap returns error EINVAL * Calling mmap on the socket file descriptor (to set the rx ring address) with MAP_SHARED | MAP_ANONYMOUS | MAP_HUGETLB | MAP_HUGE_1GB => mmap succeeds and a huge page is allocated, but the memory area is all zero and does not contain the expected ring structures. I suspect the MAP_ANONYMOUS flag makes it ignore the socket file descriptor, and the mapping is thus unrelated to the ring. * Calling mmap first to map a huge page area by opening a file on a hugetlbfs mount, and then calling mmap on the socket file descriptor (to set the ring address) with an address inside the previously mapped area => the address hint is ignored, and thus the ring is not mapped inside a huge page I am using "tpacket_v3" packet_mmap version and my kernel version is based on 4.8 (on Ubuntu 16.04). I reserve huge pages with the kernel boot command line, as recommended in Documentation/vm/hugetlbpage.txt. Thank you in advance for your guidance
