Date: Mon, 16 Apr 2001 11:34:16 +0200 From: Oscar-Ivan Lepe-Aldama <oscar@ac.upc.es> To: hackers@FreeBSD.ORG Subject: Sysctl question (again) Message-ID: <3ADABC98.B26D6C78@ac.upc.es>
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Hi!
the technical question follows the next commentary. This is the second
(third) time I post this question. I'm wondering why I haven't got any
answers. Is it because this isn't the right forum? Is it because I
haven't been clear enough? Is it because my bad english? Any clue on why
the people in this forum can not give me any kind of answer for the
following question will be aprreciated. Now, the technical question
follows.
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 pmec2;
} 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,
--
========================================================================
0 0 0 Oscar-Ivan Lepe-Aldama | UPC-Campus Nord, DAC
0 0 0 e-mail: oscar@ac.upc.es | Modul D6, despatx 116
0 0 0 phone: +34 93 401 7187 | Jordi Girona, 1-3
U P C fax: +34 93 401 7055 | 08034 Barcelona - SPAIN
WWW: http://www.ac.upc.es/homes/oscar/
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