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Intel Xeon E5-2620 is Sandy Bridge CPU which officially supports AVX and not AVX2.

DPDK 20.11 meson build, ninja -C build will generate code with AVX instructions and not AVX2. But (Based on the live debug) PKTGEN forces the compiler to add AVX2 to be inserted, thus causing illegal instruction.

Solution: edit meson.build in line 22

from

For #1 and #2, it's not clear to me whether you want the first item satisfying the condition, or the collection of distinct items that satisfy the condition.

For the first item, you could use first:

I finally got it working by inverting the MSI-X table structure found on osdev.org. I decided to completely reinitialize the xHC after leaving the UEFI environment as it could leave it in an unknown state. Here's the xHCI code for anyone wondering the same thing as me:

You can refer this post on url https://javascript.plainenglish.io/uploading-files-using-multer-on-server-in-nodejs-and-expressjs-5f4e621ccc67

I just followed it yesterday to make it work Seems your multer is not configured in the way it should be

On "mainstream" CPUs like Skylake-X and IceLake, it's only worth using 512-bit vectors at all if you use them consistently for a lot of your program's run-time, not just for an occasional memcpy. See SIMD instructions lowering CPU frequency for the details: you don't want occasional calls to memcpy to hold your CPU frequency down to a lower max turbo.

Using AVX-512 features with 256-bit vectors (AVX-512VL) can be worth it for some things, e.g. if masking is nice, or if you use YMM16..31 to avoid VZEROUPPER.

I'd guess that glibc would only resolve memcpy to __memcpy_avx512_no_vzeroupper on systems like Knight's Landing (KNL) Xeon Phi, where the CPU is designed around AVX-512, and there's no downside to using 512-bit ZMM vectors. There's no need for vzeroupper even after using ymm0..15 on KNL. In fact vzeroupper is very slow on KNL, and definitely something to avoid, hence putting no_vzeroupper in the function name.

https://code.woboq.org/userspace/glibc/sysdeps/x86_64/multiarch/memmove-avx512-no-vzeroupper.S.html is the source for that version. It uses ZMM vectors, including ZMM0..15, so if used on a Skylake/IceLake CPU it should use vzeroupper. This version looks designed for KNL.

There would be some tiny benefit to having an AVX-512VL version that used ymm16..31 to avoid vzeroupper (to speed 32 .. 64 byte copies), without ever using ZMM registers.

And it would make sense for __memcpy_avx512_no_vzeroupper to only use ZMM16..31 so avoiding vzeroupper isn't a problem on mainstream CPUs; then it would be a usable option in code that already made heavy use of AVX-512 (and thus was already paying the CPU-frequency cost.)

The code looks ok but you might have two issues...

First check that the Request Body actually is posted correctly and that the JSON is what you expect.

Secondly check that the Request Body is in fact JSON and not String. You can do this by:

You should destructure adddata as well.

There are plenty of reasons why a code can be slower with -march=native, although this is quite exceptional.

That being said, in your specific context, one possible scenario is the use of slower SIMD instructions, or more precisely different SIMD instructions finally making the program slower. Indeed, GCC vectorize loops with -O3 using the SSE instruction set on x86 processors such as yours (for backward compatibility). With -march=native, GCC will likely vectorize loops using the more advanced and more recent AVX instruction set (supported by your processor but not on many old x86 processors). While the use of AVX instruction should speed your program up, it is not always the case in few pathological cases (less efficient code generated by compiler heuristics, loops are too small to leverage AVX instructions, missing/slower AVX instructions available in SSE, alignment, transition penality, energy/frequency impact, etc.).

My guess is your program is memory bound and thus AVX instructions do not make your program faster.

You can confirm this hypothesis by enabling AVX manually using -mavx -mavx2 rather than -march=native and look if your performance issue is still there. I advise you to carefully benchmark your application using a tool like perf.

You should look in the flags section in the /proc/cpuinfo file for one of two possible values: vmx (intel) or svm (amd).

Instead of manually checking this file, you can use the grep command as in your case: