bishboria

These links no longer work. Springer have pulled the free plug.

Graduate texts in mathematics

duplicates = multiple editions

A Classical Introduction to Modern Number Theory, Kenneth Ireland Michael Rosen

A Classical Introduction to Modern Number Theory, Kenneth Ireland Michael Rosen

uucidl

On the emergence of interfaces

Interfaces naturally emerge as software gets broken down into parts communicating with one another. The larger and more deliberate structures emerge from a deliberate attempt to organize the development process itself. [fn:Liskov2008] Structure often emerge directly from division of labor: as teams take on independent tasks, interfaces are established betweeen domains they become responsible for. (Conway’s Law)

Software developers are responsible for systems built out of very small atoms while ultimately performing tasks for their users of a much greater magnitude. Dijkstra showed this by computing the ratio between grains of time at the lowest and largest atoms of the system (from say, CPU instructions to a human interaction with the system) The span was already quite large by Dijkstra’s time, of about 10^9. Today this ratio would be at least above 10^12 (see grain ratios)

This large span has to be manage

CMCDragonkai

Understanding the Memory Layout of Linux Executables

Required tools for playing around with memory:

• hexdump
• objdump
• readelf
• xxd
• gcore

pervognsen

// Xeno

enum Xeno_Kind {
    XENO_POINTER,
    XENO_AGGREGATE,
    XENO_FIRST_PRIMITIVE_TYPE,
    XENO_UINT8 = XENO_FIRST_PRIMITIVE_TYPE,
    XENO_UINT16,
    XENO_UINT32,
    XENO_UINT64,

rygorous

Why do compilers even bother with exploiting undefinedness signed overflow? And what are those
mysterious cases where it helps?

A lot of people (myself included) are against transforms that aggressively exploit undefined behavior, but
I think it's useful to know what compiler writers are accomplishing by this.

TL;DR: C doesn't work very well if int!=register width, but (for backwards compat) int is 32-bit on all
major 64-bit targets, and this causes quite hairy problems for code generation and optimization in some
fairly common cases. The signed overflow UB exploitation is an attempt to work around this.

nkurz

nate@haswell:~/src$ likwid-perfctr -m -g UOPS_ISSUED_ANY:PMC0,UOPS_EXECUTED_CORE:PMC1,UOPS_RETIRED_ALL:PMC2,BR_INST_RETIRED_NEAR_TAKEN:PMC3 -C 1 fusion
-------------------------------------------------------------
-------------------------------------------------------------
CPU type:	Intel Core Haswell processor
CPU clock:	3.39 GHz
-------------------------------------------------------------
fusion
two_micro_two_macro: sum1=10000000, sum2=9999999
one_micro_two_macro: sum1=10000000, sum2=9999999
one_micro_one_macro: sum1=10000000, sum2=9999999

-

Not all of these events have been tested and they may be broken
USE AT YOUR OWN RISK!

CBO (Last Level Cache Slice) CACHE Events
  CBO.LLC_LOOKUP                 Cache Lookups                           
  CBO.LLC_LOOKUP.ANY             Cache Lookups                           
  CBO.LLC_LOOKUP.DATA_READ       Cache Lookups                           
  CBO.LLC_LOOKUP.NID             Cache Lookups                           
  CBO.LLC_LOOKUP.READ            Cache Lookups                           

NocturnDragon

#include <stdio.h>

// #define CLANG_EXTENSION
// Clang compile with -O3

#define VS_EXTENSION
// https://godbolt.org/z/sVWrF4
// Clang  compile with -O3 -fms-compatibility
// VS2017 compile with /O3

rondy

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.

---

Effective Engineer - Notes

• By Edmond Lau
• Highly Recommended 👍
• http://www.theeffectiveengineer.com/

What's an Effective Engineer?

eshelman

Latency Comparison Numbers
--------------------------
L1 cache reference/hit                       1.5 ns                      4 cycles
Floating-point add/mult/FMA operation        1.5 ns                      4 cycles
L2 cache reference/hit                       5   ns                      12 ~ 17 cycles
Branch mispredict                            6   ns                      15 ~ 20 cycles
L3 cache hit (unshared cache line)          16   ns                      42 cycles
L3 cache hit (shared line in another core)  25   ns                      65 cycles
Mutex lock/unlock                           25   ns
L3 cache hit (modified in another core)     29   ns                      75 cycles