Hi!
is there a maximum for the size of an object that sysctl can handle?
I'm asking this because I have inserted in a 4.1.1 kernel an array
defined as
struct buf_entry {
unsgined int id;
u_int64_t tsc;
u_int64_t pmec1;
u_int64_t pcem2;
} mybuffer[NUMENTRIES];
SYSCTL_NODE(, CTL_NAVI, experiments, CTLFLAG_RW, 0,"Experiments");
SYSCTL_OPAQUE(_experiments, OID_AUTO, buffer, CTLFLAG_RD, &mybuffer,
sizeof(mybuffer), "", "");
When NUMENTRIES equals 100000 (100 thousand) everything works well; that
is, I can read the content of the array using
sysctl -b experiments.mybuffer > somefile.raw
But when NUMENTRIES equals 1000000 (1 million) and I use the above
command to read the content of the array, the system stops working
properly; that is, all virtual terminals freezed so I can't sent any
command to the system, although the kernel seams to be alive as it
responds to ICMP echo packets.
I do want to have a large array within the kernel's memory space as I'm
measuring the performance of some kernel's routines using the Pentium's
Performance Monitoring Event Counters, and the more performance data I
could get in one experiment the best.
By the way, the system under test has 64 MB of RAM and 20 GB of free
space on disk.
Any explanation on the possibility or the impossibility of having such
large array within the kernel memory-space and having it exported
through sysctlt will be verry much appreciated.
Thanks,
--
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