Ciro Santilli (@cirosantilli) - Newly followed articles

This is a quick Microarchitectural benchmark to try and determine how many functional units our CPU has that can do an inc instruction at the same time due to superscalar architecture.

The generated programs do loops like:

loop:
  inc %[i0];
  inc %[i1];
  inc %[i2];
  ...
  inc %[i_n];
  cmp %[max], %[i0];
  jb loop;

with different numbers of inc instructions.

Figure 1.
c/inc_loop_asm_n.sh results for a few CPUs
.
Quite clearly:
AMD 7840U can run INC on 4 functional units
Intel i7-7820HQ can run INC on 2 functional units
and both have low instruction count effects that destroy performance, AMD at 3 and Intel at 3 and 5. TODO it would be cool to understand those better.
Data from multiple CPUs manually collated and plotted manually with ../c/inc_loop_asm_n_manual.sh.

Announced at:

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c/inc_loop_asm.c by

Ciro Santilli 37 Created 2025-06-17 Updated 2025-07-16

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This is the only way that we've managed to reliably get a single inc instruction loop, by using inline assembly, e.g. on we do x86:

loop:
  inc %[i];
  cmp %[max], %[i];
  jb loop;

For 1s on P14s Ubuntu 25.04 GCC 14.2 -O0 x86_64 we need about 5 billion:

time ./inc_loop_asm.out 5000000000

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c/inc_loop.c by

Ciro Santilli 37 Created 2025-06-17 Updated 2025-07-16

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Ubuntu 25.04 GCC 14.2 -O0 x86_64 produces a horrendous:

11c8:       48 83 45 f0 01          addq   $0x1,-0x10(%rbp)
11cd:       48 8b 45 f0             mov    -0x10(%rbp),%rax
11d1:       48 3b 45 e8             cmp    -0x18(%rbp),%rax
11d5:       72 f1                   jb     11c8 <main+0x7f>

To do about 1s on P14s we need 2.5 billion instructions:

time ./inc_loop.out 2500000000

and:

time ./inc_loop.out 2500000000

gives:

          1,052.22 msec task-clock                       #    0.998 CPUs utilized             
                23      context-switches                 #   21.858 /sec                      
                12      cpu-migrations                   #   11.404 /sec                      
                60      page-faults                      #   57.022 /sec                      
    10,015,198,766      instructions                     #    2.08  insn per cycle            
                                                  #    0.00  stalled cycles per insn   
     4,803,504,602      cycles                           #    4.565 GHz                       
        20,705,659      stalled-cycles-frontend          #    0.43% frontend cycles idle      
     2,503,079,267      branches                         #    2.379 G/sec                     
           396,228      branch-misses                    #    0.02% of all branches

With -O3 it manages to fully unroll the loop removing it entirely and producing:

    1078:       e8 d3 ff ff ff          call   1050 <strtoll@plt>
}
    107d:       5a                      pop    %rdx
    107e:       c3                      ret

to is it smart enough to just return the return value from strtoll directly as is in rax.

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Inline assembly by

Ciro Santilli 37 Created 2025-06-17 Updated 2025-07-16

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Insulin by

Ciro Santilli 37 Created 2025-06-17 Updated 2025-07-16

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Studying insulin reveals some really cool protein motifs of life:

both the A chain and B chain are transcribed from a single gene. The resulting peptide also contain:
- the C-peptide in the middle which gets removed
- a signaling sequence telling the cell to export the substance out as it is a hormone

Figure 1.
Primary structure of insulin
. Source.

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The Amino-acid Sequence in the Phenylalanyl Chain of Insulin by

Ciro Santilli 37 Created 2025-06-17 Updated 2025-07-16

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This is where he started publishing the sequence of insulin. The paper gives the full B-chain sequence, which it tentatively calls the "Phenylalanyl Chain" because it starts with a Phenylalanyl.

The official link seems to be: portlandpress.com/biochemj/article/49/4/463/47212/The-amino-acid-sequence-in-the-phenylalanyl-chain It seems to explain the methods very well at first glance, with lots of schematics.

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Sanger method by

Ciro Santilli 37 Created 2025-06-17 Updated 2025-07-16

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C example by

Ciro Santilli 37 Created 2025-06-17 Updated 2025-07-16

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Phi X 174 by

Ciro Santilli 37 Created 2025-06-17 Updated 2025-07-16

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Peptide hormone by