2015-08-27 09:38, Jerin Jacob:

On Tue, Aug 25, 2015 at 02:03:13PM +0200, Thomas Monjalon wrote:

quoted

2015-08-18 18:10, Jerin Jacob:

quoted

--- a/app/test/test_red.c
+++ b/app/test/test_red.c
+#if defined(RTE_ARCH_X86_64) || defined(RTE_ARCH_I686) || defined(RTE_ARCH_X86_X32)
 #ifdef __PIC__
     asm volatile (
     "mov %%ebx, %%edi\n"

@@ -155,6 +156,7 @@ static inline void rdtsc_prof_start(struct rdtsc_prof *p)
 #else
 	asm( "cpuid" : : : "%eax", "%ebx", "%ecx", "%edx" );
 #endif
+#endif
 	p->clk_start = rte_rdtsc();

The right fix would be to move that arch-specific code into an EAL abstraction.

I agree. I thought the same. But I am not able to understand why 'cpuid'
instruction used here without any input/output parameters. What is the
role of 'cpuid' instruction in this specific function and what to
abstract in eal ?

It is explained here:
	http://dpdk.org/ml/archives/dev/2014-January/001182.html

I think it can be replaced by rte_rdtsc_precise() which was implemented
after the above discussion. It uses rte_mb instead of cpuid.

As explained in the following thread, memory fence can be used instead of cpuid:
	http://stackoverflow.com/a/12634857
As showed in the following threads, rdtscp can also be used:
	http://stackoverflow.com/a/27697754
	http://dpdk.org/ml/archives/dev/2015-April/016770.html

It reminds me that we should deprecate rte_rdtsc() and rte_get_tsc_cycles() in
favor of a more generic name, e.g. rte_get_clock_cycles().