Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

drv_usecwait(9f) [v7 man page]

drv_usecwait(9F)					   Kernel Functions for Drivers 					  drv_usecwait(9F)

NAME
drv_usecwait - busy-wait for specified interval SYNOPSIS
#include <sys/types.h> #include <sys/ddi.h> void drv_usecwait(clock_t microsecs); INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI). PARAMETERS
microsecs The number of microseconds to busy-wait. DESCRIPTION
drv_usecwait() gives drivers a means of busy-waiting for a specified microsecond count. The amount of time spent busy-waiting may be greater than the microsecond count but will minimally be the number of microseconds specified. delay(9F) can be used by a driver to delay for a specified number of system ticks, but it has two limitations. First, the granularity of the wait time is limited to one clock tick, which may be more time than is needed for the delay. Second, delay(9F) may only be invoked from user context and hence cannot be used at interrupt time or system initialization. Often, drivers need to delay for only a few microseconds, waiting for a write to a device register to be picked up by the device. In this case, even in user context, delay(9F) produces too long a wait period. CONTEXT
drv_usecwait() can be called from user or interrupt context. SEE ALSO
delay(9F), timeout(9F), untimeout(9F) Writing Device Drivers NOTES
The driver wastes processor time by making this call since drv_usecwait() does not block but simply busy-waits. The driver should only make calls to drv_usecwait() as needed, and only for as much time as needed. drv_usecwait() does not mask out interrupts. SunOS 5.10 12 Nov 1992 drv_usecwait(9F)

Check Out this Related Man Page

drv_usecwait(9F)					   Kernel Functions for Drivers 					  drv_usecwait(9F)

NAME
drv_usecwait - busy-wait for specified interval SYNOPSIS
#include <sys/types.h> #include <sys/ddi.h> void drv_usecwait(clock_t microsecs); INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI). PARAMETERS
microsecs The number of microseconds to busy-wait. DESCRIPTION
drv_usecwait() gives drivers a means of busy-waiting for a specified microsecond count. The amount of time spent busy-waiting may be greater than the microsecond count but will minimally be the number of microseconds specified. delay(9F) can be used by a driver to delay for a specified number of system ticks, but it has two limitations. First, the granularity of the wait time is limited to one clock tick, which may be more time than is needed for the delay. Second, delay(9F) may only be invoked from user context and hence cannot be used at interrupt time or system initialization. Often, drivers need to delay for only a few microseconds, waiting for a write to a device register to be picked up by the device. In this case, even in user context, delay(9F) produces too long a wait period. CONTEXT
drv_usecwait() can be called from user or interrupt context. SEE ALSO
delay(9F), timeout(9F), untimeout(9F) Writing Device Drivers NOTES
The driver wastes processor time by making this call since drv_usecwait() does not block but simply busy-waits. The driver should only make calls to drv_usecwait() as needed, and only for as much time as needed. drv_usecwait() does not mask out interrupts. SunOS 5.10 12 Nov 1992 drv_usecwait(9F)
Man Page

8 More Discussions You Might Find Interesting

1. BSD

Reduce boot-time delay on FreeBSD?

Say for instance, I would like to reduce the delay/waiting time for the boot-time menu from 10 seconds to 5 seconds, how would I go about doing it? From what I've been able to find, entering "autoboot 5" into the right file would take care of that for me, but the man pages are unclear as to... (1 Reply)
Discussion started by: DownSouthMoe
1 Replies

2. AIX

system disks on aix 5.3

hello i'm running on P570 box aix 5.3 8 cpus 24G ram there are 1850 users loged in to this box the problem is that the two sysytem disks busy all the time hdisk0 100% busy hdisk1 100% busy some one have an idea what writing to this disks? thanks ariec (9 Replies)
Discussion started by: ariec
9 Replies

3. AIX

CIO/DIO and JFS2 read ahead

Hi Guys, I wonder if after enabling CIO/DIO at the filesystem level and assuming that CIO/DIO will bypass the JFS2 read ahead available when not using CIO/DIO my questionis what parameters I can play with to tune/improve the CIO in order to obtain similar performance for sequential reads (... (7 Replies)
Discussion started by: hariza
7 Replies

4. Solaris

Finding most busy file system

Hi Experts, I was asked to find most busy file system on one of the server. It is Sun 10. Any idea to get this? Thanks, Deepak (5 Replies)
Discussion started by: naw_deepak
5 Replies

5. AIX

how to write a script to let cpu busy?

how to write a script to let cpu busy? and how to write a script to let memory/disk busy? (5 Replies)
Discussion started by: rainbow_bean
5 Replies

6. UNIX for Dummies Questions & Answers

modprobe spi_bitbang results in error messages

Hi, I'm having a problem with the voyage linux distribution. I've been busy to include a CAN driver, which uses the SPI bus to communicate. While I was busy debugging the code, everything worked fine while performing a modprobe of the SPI driver to get it all running. But the... (1 Reply)
Discussion started by: nistap
1 Replies

7. Programming

Sleep function not detected

Hello Im using geany to write my c codes. Below is my code to make the internal LED of beaglebone flashing. But i cant seem to use the sleep or delay to make the program wait for a couple of miliseconds. I've included all include files that i can find but none of it solve the problem. Any help is... (1 Reply)
Discussion started by: HellRyder
1 Replies

8. AIX

Need to know %age disk busy on AIX

Hi , Following alerts are coming for %busy device on a server Disk Device hdisk5 is 100% busy Please assist how do I analyse this and also how do I check the %age busy for hdisk5. Best regards, Vishal (4 Replies)
Discussion started by: Vishal_dba
4 Replies