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Top Forums UNIX for Beginners Questions & Answers 32 bit process addressing more than 4GB Post 303042500 by MadeInGermany on Friday 27th of December 2019 07:15:43 AM
Old 12-27-2019
PAE was invented for 32bit kernels, in order to address more than 4GB.
It allowed many apps to consume more than 4GB, but I have my doubts that a single app could address more than 4GB.

PAE caused some severe misbehavior on Linux: for example, OOM killer was invoked if one 4GB segment was full; without knowing which process occupied most in that segment it often killed "wrong" processes before it killed a "correct" one. OpenSuSE kernels even invoked OOM killer if a single small process did continous I/O that filled a 4GB segment with only cache data - a nightmare!
Fortunately PAE is from the past - today there are 64bit kernels.

Solaris never had OOM killer, and Sparc early supported 64bit - there was no need for something like PAE.
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sg_get_network_io_stats(3)				     Library Functions Manual					sg_get_network_io_stats(3)

NAME
sg_get_network_io_stats, sg_get_network_io_stats_diff - get network statistics SYNOPSIS
#include <statgrab.h> sg_network_io_stats *sg_get_network_io_stats(int *entries); sg_network_io_stats *sg_get_network_io_stats_diff(int *entries); DESCRIPTION
Both calls take a pointer to an int, entries, which is filled with the number of network interfaces the machine has. This is needed to know how many sg_network_io_stats structures have been returned. A pointer is returned to the first sg_network_io_stats. sg_get_network_io_stats returns the network traffic stored in the kernel which holds the amount of data transferred since bootup. On some platforms, such as Solaris 7, this value is stored in a 32bit int, so wraps around when it reaches 4GB. Other platforms, such as Solaris 8, hold the value in a 64bit int, which wraps somewhere near 17 million terabytes. sg_get_network_io_stats also returns the number of packets sent and received, and the number of errors that have occured. It also makes the number of collisions available. sg_get_network_io_stats_diff is the same as sg_get_network_io_stats except it will return the difference since the last call. So, for instance a call to sg_get_network_io_stats_diff is made, and called again 5 seconds later. Over that time, 20 bytes of traffic was trans- mitted and 10 bytes received. Tx will store 20, rx will store 10 and systime will store 5. This function copes with wrap arounds by the O/S so should be seemless to use. RETURN VALUES
All network statistics return a pointer to a structure of type sg_network_io_stats. typedef struct{ char *interface_name; long long tx; long long rx; long long ipackets; long long opackets; long long ierrors; long long oerrors; long long collisions; time_t systime; }sg_network_io_stats; interface_name The name known to the operating system. (eg. on linux it might be eth0) tx The number of bytes transmitted. rx The number of bytes received. ipackets The number of packets received. opackets The number of packets transmitted. ierrors The number of receive errors. oerrors The number of transmit errors. collisions The number of collisions. systime The time period over which tx and rx were transferred. BUGS
On the very first call sg_get_network_io_stats_diff will return the same as sg_get_network_io_stats. After the first call it will always return the difference. On operating system that hold only 32bits of data there is a problem if the values wrap twice. For example, on Solaris 7 if 9GB is trans- ferred and the operating system wraps at 4GB, the sg_get_network_io_stats_diff function will return 5GB. SEE ALSO
statgrab(3) WEBSITE
http://www.i-scream.org/libstatgrab/ i-scream $Date: 2005/04/25 11:25:45 $ sg_get_network_io_stats(3)
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