Hi!
On 20:53 Wed 18 Aug , Daniel Baluta wrote:
Hello,
On Wed, Aug 18, 2010 at 8:07 PM, Parmenides mobile.parmeni...@gmail.com
wrote:
Hi,
For a critical section protected by a spin lock, kernel preemption is
disabled explicitly, probably to make the critical section atomic
Hi!
On 01:07 Thu 19 Aug , Parmenides wrote:
Hi,
For a critical section protected by a spin lock, kernel preemption is
disabled explicitly, probably to make the critical section atomic.
But, suppose that an interrupt occures in this critical section,
allowing interrupts can wreck
Hi,
For a critical section protected by a spin lock, kernel preemption is
disabled explicitly, probably to make the critical section atomic.
But, suppose that an interrupt occures in this critical section,
allowing interrupts can wreck the atomicity. So, why don't we disable
interrupts
Hello,
On Wed, Aug 18, 2010 at 8:07 PM, Parmenides mobile.parmeni...@gmail.com wrote:
Hi,
For a critical section protected by a spin lock, kernel preemption is
disabled explicitly, probably to make the critical section atomic.
But, suppose that an interrupt occures in this critical section
Why is preemption disabled before a lock is acquired in _spin_lock function?
As the critical region of code which is to be protected by the spin
lock executes only after the lock is acquired, why is disabling of
preemption required before the lock is acquired?
Wouldn't it better if the kernel
...@gmail.com wrote:
Why is preemption disabled before a lock is acquired in _spin_lock function?
As the critical region of code which is to be protected by the spin
lock executes only after the lock is acquired, why is disabling of
preemption required before the lock is acquired?
Wouldn't
Hi Joel...
On Sun, Jan 17, 2010 at 9:34 PM, Joel Fernandes agnel.j...@gmail.com wrote:
Why is preemption disabled before a lock is acquired in _spin_lock function?
As the critical region of code which is to be protected by the spin
lock executes only after the lock is acquired, why
On Sun, Jan 17, 2010 at 10:34 PM, Joel Fernandes agnel.j...@gmail.com wrote:
Why is preemption disabled before a lock is acquired in _spin_lock function?
theoretically, if your interrupt handling codes is sharing some data
with your kernel codes, then assuming u have one CPU, it is possible
and where kernel preemption is *triggered*. Please correct me if I did
misunderstand anything.
It is triggered by the timer interrupt. This is an interrupt which fires
periodically on configureable intervals. It does not only preempt the kernel,
but user space processes as well. If it fires
and when the
kernel *can* get preempted, however what I really want to know is when
and where kernel preemption is *triggered*. Please correct me if I did
misunderstand anything.
It is triggered by the timer interrupt. This is an interrupt which fires
periodically on configureable intervals
Gamal wrote:
...
As far as I understood, Michi's answer explains why and when the
kernel *can* get preempted, however what I really want to know is when
and where kernel preemption is *triggered*. Please correct me if I did
misunderstand anything.
It is triggered by the timer interrupt
...@michaelblizek.twilightparadox.com wrote:
Hi!
On 00:08 Fri 14 Aug , Mohammed Gamal wrote:
...
As far as I understood, Michi's answer explains why and when the
kernel *can* get preempted, however what I really want to know is when
and where kernel preemption is *triggered*. Please correct me
Hi All,
I know that kernel preemption exists in order to allow high-priority
processes to interrupt the kernel if the kernel executes on relatively
long code paths in order to improve latency times and process
responsiveness. However, I am curious to know when and where the
kernel gets preempted
Hi!
On 15:59 Thu 13 Aug , Mohammed Gamal wrote:
Hi All,
I know that kernel preemption exists in order to allow high-priority
processes to interrupt the kernel if the kernel executes on relatively
long code paths in order to improve latency times and process
responsiveness.
Not only high
Hi Mohammed,
On Thu, 2009-08-13 at 15:59 +0300, Mohammed Gamal wrote:
Hi All,
I know that kernel preemption exists in order to allow high-priority
processes to interrupt the kernel if the kernel executes on relatively
long code paths in order to improve latency times and process
On Thu, Aug 13, 2009 at 11:02 PM,
Microbit_Ubuntumicro...@virginbroadband.com.au wrote:
Hi Mohammed,
On Thu, 2009-08-13 at 15:59 +0300, Mohammed Gamal wrote:
Hi All,
I know that kernel preemption exists in order to allow high-priority
processes to interrupt the kernel if the kernel executes
Hi!
On 00:08 Fri 14 Aug , Mohammed Gamal wrote:
...
As far as I understood, Michi's answer explains why and when the
kernel *can* get preempted, however what I really want to know is when
and where kernel preemption is *triggered*. Please correct me if I did
misunderstand anything
:32
*To:* kernelnewbies@nl.linux.org
*Subject:* preemption
Dear All,
I have some confusion about preemption. Can anybody please clear my query :
1) If there are two process running in kernel space one of them has a
lock its preempt_count value is +ve , can the other process preempt
a process of
lower priority.
If pre-empt_count is +ve means that i can be pre-empted then you are
right.
If a lower process has taken a lock its preempt_count value is +ve , can
it be preempted by higher priority process ?
positive value of preempt_count means that kernel preemption
priority process ?
positive value of preempt_count means that kernel preemption is disabled, in
that case even high priority process will not be able to preempt low
priority process, people please CMIIW
This is correct. A positive value disables preemption.
From: kernelnewbies-bou
Dear All,
I have some confusion about preemption. Can anybody please clear my query :
1) If there are two process running in kernel space one of them has a lock
its preempt_count value is +ve , can the other process preempt it ? If
it preempt the first process ( which is in running state
On Thu, Jul 30, 2009 at 2:31 PM, er krishnaerkris...@gmail.com wrote:
Dear All,
I have some confusion about preemption. Can anybody please clear my query :
1) If there are two process running in kernel space one of them has a lock
its preempt_count value is +ve , can the other process
that
process; even if any process higher than that comes.
On Thu, Jul 30, 2009 at 2:31 PM, er krishna erkris...@gmail.com wrote:
Dear All,
I have some confusion about preemption. Can anybody please clear my query :
1) If there are two process running in kernel space one of them has a
lock its
On Thu, Jul 30, 2009 at 2:31 PM, er krishnaerkris...@gmail.com wrote:
Dear All,
I have some confusion about preemption. Can anybody please clear my query :
1) If there are two process running in kernel space one of them has a lock
its preempt_count value is +ve , can the other process
Mulyadi, thank you for the detailed explanation. Thus
(a) is a source for interrupt latency and (b) actually fixes it.
--
Kostya
Date: Thu, 25 Jun 2009 02:26:25 +0700
Subject: Re: preemption
From: mulyadi.sant...@gmail.com
To: bkos...@hotmail.com
Subject: Re: preemption
From: mulyadi.sant...@gmail.com
To: bkos...@hotmail.com
CC: kernelnewbies@nl.linux.org
Hi...
2009/6/24 Kostya B :
Dear list,
Please help me to analyze the following scenario:
By having a userspace process 'A' executing a system call.
Hardware interrupt
Dear list,
Please help me to analyze the following scenario:
By having a userspace process 'A' executing a system call.
Hardware interrupt happens. Do you think on exit from interrupt (irq_exit)
the context switch could take place? Let's assume no softirq work is pending.
(a) kernel
it could, depending on the preemption model you pick...see below
Let's assume no softirq work is pending.
(a) kernel is not preemptive
then it would stay in the current kernel code path, which is executing
the syscall on behalf of running task.
(b) kernel is preemptive
What I am quite
PM
To: micro...@virginbroadband.com.au
Cc: Kernelnewbies
Subject: Re: About Kernel preemption and kernel mode stack
Hi!
On 12:15 Fri 06 Mar , micro...@virginbroadband.com.au wrote:
...
In this case it's common to use co-operative scheduling. This means that
when a task does not need further
Hi!
On 13:00 Thu 05 Mar , Pranav Peshwe wrote:
On Thu, Mar 5, 2009 at 11:48 AM, Michael Blizek
mic...@michaelblizek.twilightparadox.com wrote:
Hi!
On 23:47 Wed 04 Mar , sahlot arvind wrote:
Hi All,
...
2. If kernel is not preemptible then do we really need a separate
2009/3/6 micro...@virginbroadband.com.au
Anyway in any case how does shell get the 'd' or anything from the
keyboard?
What are the exact steps?
I'm a Linux kernel newbie, (although I have heavy embedded MCU coding
background) but I can help with the general approach of this scenario.
Hi!
On 12:15 Fri 06 Mar , micro...@virginbroadband.com.au wrote:
...
In this case it's common to use co-operative scheduling. This means that
when a task does not need further execution, it must relinquish control
back to the scheduler. I personally find this a real pig to program like
On Thu, Mar 5, 2009 at 11:48 AM, Michael Blizek
mic...@michaelblizek.twilightparadox.com wrote:
Hi!
On 23:47 Wed 04 Mar , sahlot arvind wrote:
Hi All,
Just had couple of questions:
1. kernel is preemptible if we are running in kernel mode and not holding
any lock. What if we
On Thu, Apr 10, 2008 at 3:32 PM, bhanu nani [EMAIL PROTECTED] wrote:
Hi all,
I am trying to test kernel preemption in my driver. When I first
compiled the Linux kernel and tested it, I found it to be
non-preemptible. Later I realised that my kernel was build with
premption disabled. I
not preempt the kernel process and give back the
control to terminal prompt.
The kernel only gives control back after the delay is complete.
I was thinking CTRL+C should generate a preemption signal to kernel.
If not, I would like to know what are those signals that can trigger a
preemption in kernel mode
a preemption signal to kernel.
If not, I would like to know what are those signals that can trigger a
preemption in kernel mode.
preemption means that process a running kernel code can be interrupted
at more or less any time for some higher priority process b. when
process a eventually runs
was thinking CTRL+C should generate a preemption signal to kernel.
If not, I would like to know what are those signals that can trigger a
preemption in kernel mode.
OK, I think I know. mdelay() is busy looping, thus your code path
force you to stay in kernel space for that period. Combined
Hi all,
I am trying to test kernel preemption in my driver. When I first
compiled the Linux kernel and tested it, I found it to be
non-preemptible. Later I realised that my kernel was build with
premption disabled. I enabled kernel premption in processort section
i.e. CONFIG_PREEMPT and rebuild
Hi,
Test code:
--
read()
{
if(down_interruptible())
return error;
mdelay(1);
up();
}
With this code in place, I try to do a 'CTRL+C' when it hangs at that
delay. It does not respond to my 'CTRL + C'.
Where am I missing the preemption thing
Hi...
On Thu, Apr 10, 2008 at 2:32 PM, bhanu nani [EMAIL PROTECTED] wrote:
Hi all,
I am trying to test kernel preemption in my driver. When I first
compiled the Linux kernel and tested it, I found it to be
non-preemptible. Later I realised that my kernel was build with
premption
Hi list,
Does the preempt_disable() disable preemption on all the processors or just the
current processor?
Thanks,
Rajat
--
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Please read the FAQ at http://kernelnewbies.org/FAQ
And the get_cpu() ? Its not supposed to disable preemption in all cpus?
from include/linux/smp.h:
#define get_cpu() ({ preempt_disable(); smp_processor_id(); })
rjm;
On 9/28/07, Mulyadi Santosa [EMAIL PROTECTED] wrote:
HI...
Does the preempt_disable() disable preemption on all
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