I have an issue with performance of oracle, the db sits on EBS volumes on and aws EC2 instance. I have captured the iostat data and feed it to iostat_plotter to forward it to the DB administrators. However what I'm trying to understand is the variable avgrq-sz, it is quite in consistent.
The system is running RHEL 6.4 64 bit, Oracle 11g. The block size is 4K .Following is the extract for two devices which are of interest
and
These samples are one sec apart. My first guess is that the data sets which are being processed by oracle need reindexing.
Hi
I am using HP - UX...
When I execute the below commands I get these results...
Why do i get a different shell value when i run echo $SHELL?
# echo $0
ksh
# echo $SHELL
sh
# ps -p$$
PID TTY TIME COMMAND
4013 pts/7 0:00 ksh (2 Replies)
I am using a piece of code which is working fine in some cases and is not working in some other instances. All I am doing is grep'ing and concatenating.
Below is a working scenario.
$ echo $var1
REPLYFILENAME=Options_NSE1.txt.enc
$ FILE_NM=`echo ${var1##*=}`.gz (Take everything after... (1 Reply)
Hi
I'm executing a menu script in which I `cat a file` but it's giving different output some times. Following is the code fragment taken from my script.
while true
do
cat procs.configured
echo ---------separator--------------
sleep 3
done
when I execute this code fragment, `cat` outputs... (2 Replies)
The command ps -eaf gives inconsistent result when executed on XYZ server (the command shows 1, 2 or 3 instances of the process. Ideally it should show only 1). I have attached the script file that was executed and the corresponding output. When the same script was executed on ABC server it gave... (1 Reply)
I have an input list of:
I am just trying to turn this list into its seconds since epoch "+%s" time equivalent. I'm trying to use the following, but every time I run the command it gives me different answers, they are close, but never the same... any clues as to why?
xargs -I{} date -j -f... (3 Replies)
Hi,
I have a file that has inconsistently numbered columns.
Like row1 has 23 columns, and row 2 has 34 columns etc.
I would like to re-order the first 8 columns as required and from the 9th column till the end, I would like to print it as it is.
I tried to read the re-ordered 8 columns... (7 Replies)
I'm trying to sort the list below, so that multiple instances of the form
pass=i_d=j
are contiguous. Curiously, the standard sort command to do this works some of the time (it produced the output below) but not all of the time.
the command I used was
cat fileName | sort -k1.26,1.26n... (3 Replies)
On one of the Unix server B.11.31. a disk that has been provisioned from the VMAX, but according to the diskinfo its show coming from clarion.
sudo /opt/emc/SYMCLI/bin/symvg sho /dev/vg_<name>
Volume Group Name : /dev/vg_<name>
Volume Group Type : HP-UX LVM
Volume Group State ... (0 Replies)
Could you please advise on the following: I have two space-delimited files with 9 and 10 columns, respectively, with exactly the same values in column 1. However, the order of column 1 differs between the two files, so I want to sort both files by column 1, so that I can align them and... (6 Replies)
Discussion started by: aberg
6 Replies
LEARN ABOUT FREEBSD
ffclock_setestimate
FFCLOCK(2) BSD System Calls Manual FFCLOCK(2)NAME
ffclock_getcounter, ffclock_getestimate, ffclock_setestimate -- Retrieve feed-forward counter, get and set feed-forward clock estimates
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/timeffc.h>
int
ffclock_getcounter(ffcounter *ffcount);
int
ffclock_getestimate(struct ffclock_estimate *cest);
int
ffclock_setestimate(struct ffclock_estimate *cest);
DESCRIPTION
The ffclock is an alternative method to synchronise the system clock. The ffclock implements a feed-forward paradigm and decouples the
timestamping and timekeeping kernel functions. This ensures that past clock errors do not affect current timekeeping, an approach radically
different from the feedback alternative implemented by the ntpd daemon when adjusting the system clock. The feed-forward approach has demon-
strated better performance and higher robustness than a feedback approach when synchronising over the network.
In the feed-forward context, a timestamp is a cumulative value of the ticks of the timecounter, which can be converted into seconds by using
the feed-forward clock estimates.
The ffclock_getcounter() system call allows the calling process to retrieve the current value of the feed-forward counter maintained by the
kernel.
The ffclock_getestimate() and ffclock_setestimate() system calls allow the caller to get and set the kernel's feed-forward clock parameter
estimates respectively. The ffclock_setestimate() system call should be invoked by a single instance of a feed-forward synchronisation dae-
mon. The ffclock_getestimate() system call can be called by any process to retrieve the feed-forward clock estimates.
The feed-forward approach does not require that the clock estimates be retrieved every time a timestamp is to be converted into seconds. The
number of system calls can therefore be greatly reduced if the calling process retrieves the clock estimates from the clock synchronisation
daemon instead. The ffclock_getestimate() must be used when the feed-forward synchronisation daemon is not running (see USAGE below).
The clock parameter estimates structure pointed to by cest is defined in <sys/timeffc.h> as:
struct ffclock_estimate {
struct bintime update_time; /* Time of last estimates update. */
ffcounter update_ffcount; /* Counter value at last update. */
ffcounter leapsec_next; /* Counter value of next leap second. */
uint64_t period; /* Estimate of counter period. */
uint32_t errb_abs; /* Bound on absolute clock error [ns]. */
uint32_t errb_rate; /* Bound on counter rate error [ps/s]. */
uint32_t status; /* Clock status. */
int16_t leapsec_total; /* All leap seconds seen so far. */
int8_t leapsec; /* Next leap second (in {-1,0,1}). */
};
Only the super-user may set the feed-forward clock estimates.
RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the
error.
ERRORS
The following error codes may be set in errno:
[EFAULT] The ffcount or cest pointer referenced invalid memory.
[EPERM] A user other than the super-user attempted to set the feed-forward clock parameter estimates.
USAGE
The feed-forward paradigm enables the definition of specialised clock functions.
In its simplest form, ffclock_getcounter() can be used to establish strict order between events or to measure small time intervals very accu-
rately with a minimum performance cost.
Different methods exist to access absolute time (or "wall-clock time") tracked by the ffclock. The simplest method uses the ffclock sysctl
interface kern.ffclock to make the system clock return the ffclock time. The clock_gettime(2) system call can then be used to retrieve the
current time seen by the feed-forward clock. Note that this setting affects the entire system and that a feed-forward synchronisation daemon
should be running.
A less automated method consists of retrieving the feed-forward counter timestamp from the kernel and using the feed-forward clock parameter
estimates to convert the timestamp into seconds. The feed-forward clock parameter estimates can be retrieved from the kernel or from the
synchronisation daemon directly (preferred). This method allows converting timestamps using different clock models as needed by the applica-
tion, while collecting meaningful upper bounds on current clock error.
SEE ALSO date(1), adjtime(2), clock_gettime(2), ctime(3)HISTORY
Feed-forward clock support first appeared in FreeBSD 10.0.
AUTHORS
The feed-forward clock support was written by Julien Ridoux <jridoux@unimelb.edu.au> in collaboration with Darryl Veitch
<dveitch@unimelb.edu.au> at the University of Melbourne under sponsorship from the FreeBSD Foundation.
BSD November 21, 2011 BSD