Intel ISA Extensions

Is profiling information running on SDE accurate and trustable?

Hi,

         I am trying to look at AVX 512 performance, currently, I wrote a simple function for evaluation as below, I configured the optimization and enabled AVX-512 etc in the project properties setting(vs2013 integrated with Intel-parallel-studio ), and I see the AVX-512 instructions are used from the asm files generated by compiler.

void complexVectorConjMpy(float *inputPtr1, float *inputPtr2, float *outputPtr, int numData)
{
    int idxData;
    float data1Re, data1Im, data2Re, data2Im;

Measuring Core Voltage

I am using an Atom N2600 processor. The intel software developer's manual says that a p-state can be requested by writing to MSR 0x199 and the locked p-state can be seen in MSR 0x198. The way to compute Core Voltage is given as MSR_PERF_STATUS[47:32] * (float) 1/(2^13).

The data that I see in MSR_PERF_STATUS (MSR 0x198) is 62d104306001045. Bits [47:32] is always 1043 irrespective of the value that I set in MSR 0x199.

When I use the formula: 0x1043 = 4163. Voltage = 4163/(2^13)=0.5 V, which is a really low voltage for the processor to operate stably at.

why does _mm_mulhrs_epi16() always do biased rounding to positive infinity?

Does anyone know why the pmulhrsw instruction or

_mm_mulhrs_epi16(x) := RoundDown((x * y + 16384) / 32768)

always rounds towards positive infinity? To me, this is terribly biased for negative numbers, because then a sequence like -0.6, 0.6, -0.6, 0.6, ... won't add up to 0 on average.

Is this behavior intentional or unintentional? If it's intentional, what could be the use? Is there an easy way to make it less biased?

Lucky for me, I can just change the order of my operations to get a less biased result (my function is a signed geometric mean):

What does it implies to disable syscall in Intel SGX

I'm looking into programming with Intel Software Guard Extensions (SGX) facility recently. The idea of SGX is to create an enclave in which security-sensitive code is loaded and executed. Most importantly memory access (and many other restrictions) to that enclave is enforced by hardware.

Interpreting Intel SDE avx/sse transition tracker

Hello, I am running Intel SDE in 'ast' mode (AVX/SSE Transition tracker.) on Mac OSX. I struggle to interpret the results.

First off, in the output, it shows function addresses, not function names. Should it not show the symbols? I built my app with -g.

Next, this is the output I see: are these numbers indicative of excessive transitions? Or are they in a normal range?

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