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sleep working
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sleep(9r) sleep(9r) NAME
sleep - General: Puts a calling process to sleep SYNOPSIS
void sleep( caddr_t *channel, long pri ); ARGUMENTS
Specifies a unique address associated with the calling kernel thread to be put to sleep. Specifies whether the sleep request is interrupt- ible. Setting this argument to the PCATCH flag causes the process to sleep in an interruptible state (that is, the kernel thread can take asynchronous signals). Not setting the PCATCH flag causes the process to sleep in an uninterruptible state (that is, the kernel thread can- not take asynchronous signals). DESCRIPTION
The sleep routine puts a calling process to sleep on the address specified by the channel argument. Some common addresses are the lbolt argument, a buf structure, and a proc structure. This address should be unique to prevent unexpected wake/sleep cycles, which can occur if different processes are sleeping on the same address accidentally. If you set the PCATCH flag in the pri argument, the sleep routine puts signals on the queue and does not wake up the sleeping process. The sleep and wakeup routines block and then wake up a process. Generally, device drivers call these routines to wait for the transfer to complete an interrupt from the device. That is, the write routine of the device driver sleeps on the address of a known location, and the device's Interrupt Service Interface (ISI) wakes the process when the device interrupts. It is the responsibility of the wakened process to check if the condition for which it was sleeping has been removed. NOTES
The operating system provides two ways to put a process to sleep: interruptible and uninterruptible. The sleep routine performs an uninter- ruptible sleep operation if you do not set the PCATCH flag and an interruptible sleep operation if you set the PCATCH flag. This means that device drivers cannot call sleep at interrupt context because at interrupt context there is no calling process to be put to sleep. Thus, a device driver's Interrupt Service Interface (ISI) and those routines called from within the ISI must not call the sleep routine. On this operating system, you cannot use pri to set the scheduling priority of the calling process. RETURN VALUES
None FILES
SEE ALSO
Routines: wakeup(9r) sleep(9r)
