BUF_UNLOCK(9) BSD Kernel Developer's Manual BUF_UNLOCK(9)NAME
BUF_UNLOCK -- unlocks a locked buffer
SYNOPSIS
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/bio.h>
#include <sys/buf.h>
void
BUF_UNLOCK(struct buf *bp);
DESCRIPTION
The BUF_UNLOCK() function unlocks a buffer that was previously locked with BUF_LOCK() or BUF_TIMELOCK().
Its argument is:
bp The buffer to unlock. The buffer must already be locked.
SEE ALSO buf(9), BUF_LOCK(9), BUF_TIMELOCK(9), lockmgr(9)AUTHORS
This manual page was written by Chad David <davidc@acns.ab.ca>.
BSD July 9, 2001 BSD
Check Out this Related Man Page
PBUF(9) BSD Kernel Developer's Manual PBUF(9)NAME
pbuf, getpbuf, trypbuf, relpbuf -- functions for managing physical buffers
SYNOPSIS
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
struct buf *
getpbuf(int *pfreecnt);
struct buf *
trypbuf(int *pfreecnt);
void
relpbuf(struct buf *bp, int *pfreecnt);
DESCRIPTION
These functions are used to allocate and release physical buffers.
The physical buffers are allocated at system startup and are maintained in a separate pool from the main system buffers. They are intended
for use by subsystems that cannot or should not be reliant on the main pool of buffers (for example the swap pager). The system allocates
between 16 and 256 physical buffers depending on the amount of memory in the system.
Each subsystem that allocates buffers via these calls is expected to manage its own percentage free counter. If the value is initialized to
-1 the number of buffers available to the subsystem is limited only by the number of physical buffers available. The number of buffers is
stored in nswbuf which is defined in <sys/buf.h> and initialized in cpu_startup(). A recommended initialization value is 1/2 nswbuf.
The getpbuf() function returns the first available buffer to the user. If there are no buffers available, getpbuf() will sleep waiting for
one to become available. If pfreecnt is zero, getpbuf() will sleep until it increases. pfreecnt is decremented prior to returning.
The trypbuf() function returns the first available buffer. If there are no buffers available, NULL is returned. As well, if pfreecnt is
zero, NULL is returned. pfreecnt is decremented prior to returning a valid buffer. If NULL is returned, pfreecnt is not modified.
The relpbuf() function releases the buffer back to the free list. If the buffers b_rcred or b_wcred structures are not NULL, they are freed.
See crfree(9).
pfreecnt is incremented prior to returning.
RETURN VALUES
getpbuf() and trypbuf() return a pointer to the buffer. In the case of trypbuf(), NULL can also be returned indicating that there are no
buffers available.
AUTHORS
This manual page was written by Chad David <davidc@acns.ab.ca>.
BSD July 9, 2001 BSD
I have a huge matrix file containing some 1.5 million rows and 6000 columns. The matrix looks something like this:
1 2 3
4 5 6
7 8 9
3 4 5
I want to add all the numbers in the columns of this matrix and display the result to my stdout. This means that the numbers in the first column are:
... (2 Replies)
Hi,
Just trying to get to grips with sed and awk for some reporting for work and I need some assistance:
I have a file that lists policy names on the first line and then on the second line whether the policy is active or not.
Policy Name: Policy1
Active: yes
Policy... (8 Replies)
version info :
vi availabe with RHEL 5.4
I have a text file with 10,000 lines. I want to copy lines from 5000th line to 7000th and redirect to a file. Any idea how I can do this?
Note:
The above scenario is just an example. In my actual requirement, the file has 14 million lines and I want... (9 Replies)
Hi everyone,
I know the following questions are noobish questions but I am asking them because I am confused about the basics of history behind UNIX and LINUX.
Ok onto business, my questions are-:
Was/Is UNIX ever an open source operating system ?
If UNIX was... (21 Replies)
Hello,
I couldn't find an actual introduction thread, so I decided to just put this here.
I go by d0wngrade online. I have been programming in multiple languages for about 15+ years. I started with standard web design languages like HTML and CSS, but I then advanced from design to development... (2 Replies)
Hi guys...
The first active code line in AudioScope.sh is set -u .
This causes a complete exit if a variable is used/found but has not been allocated at the start of the program.
However, apart from writing code to do the task, is there a switch to to check which variables have been... (17 Replies)
Hi.
In thread https://www.unix.com/shell-programming-and-scripting/267833-grouping-counting.html rovf and I had a mini-discussion on grep and awk.
Here is a demo script that compares the awk and grep approaches for this single problem:
#!/usr/bin/env bash
# @(#) s2 Demonstrate group... (1 Reply)
Hello,
I have to fish out some specific columns from a file based on the header value. I have the list of columns I need in a different file. I thought I could read in the list of headers I need,
# file with header names of required columns in required order
headers_file=$2
# read contents... (11 Replies)
For those interested in installing dash shell on OSX Lion to help test POSIX compliancy of shell scripts, it is quite easy. I did it like this:
If you don't have gcc on your system:
0. Download and install the Command Line Tools for Xcode package from Sign In - Apple *
1. Download the dash... (2 Replies)
Hello and thanks in advance for any help anyone can offer me
I'm trying to learn the find command and thought I was understanding it... Apparently I was wrong. I was doing compound searches and I started getting weird results with the -size test. I was trying to do a search on a 1G file owned by... (14 Replies)
I have data of an excel files as given below,
file1
org1_1 1 1 2.5 100
org1_2 1 2 5.5 98
org1_3 1 3 7.2 88
file2
org2_1 1 1 2.5 100
org2_2 1 2 5.5 56
org2_3 1 3 7.2 70
I have multiple excel files as above shown.
I have to copy column 1, column 4 and paste into a new excel file as... (26 Replies)
Dear All,
Taking a break from Vue.js coding for the site, SEO and YT videos; and hopefully addressing some well deserved criticism from some here that I have been too focused on the visual aspects of the forums versus the substance and the community....
While the "current generation... (9 Replies)
Hi all...
Well guys and gals, I jumped in at the deep end and found things that PERL cannot do by default.
Many tricky terminal escape codes are not catered for so I had to create workarounds.
One thing I searched for was this:
Passing perl variable to shell command
AND, @Neo this was... (15 Replies)