how to process data recvd from a device that wont give interrupts

Hi all,

I found that you can use a kernel timer and poll for the hardware
interrupt registers whether the interrupt flag is set or not,

but this will take atleast some good amount of CPU.

are there any ways other than using the kernel timer?

thanks,

Hi...

On Thu, Oct 4, 2012 at 7:03 PM, devendra.aaru [off-list ref] wrote:

Hi all,

I found that you can use a kernel timer and poll for the hardware
interrupt registers whether the interrupt flag is set or not,

but this will take atleast some good amount of CPU.

yeah, thing is, as you know, timer fires interrupt and CPU will
certainly have to service it. So, it's impossible to work around it
IMHO

are there any ways other than using the kernel timer?

perhaps something less intrusive like creating kernel thread and its
function is solely checking register state?

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

On Thu, Oct 4, 2012 at 1:50 PM, Mulyadi Santosa
[off-list ref] wrote:

Hi...

On Thu, Oct 4, 2012 at 7:03 PM, devendra.aaru [off-list ref] wrote:

quoted

Hi all,

I found that you can use a kernel timer and poll for the hardware
interrupt registers whether the interrupt flag is set or not,

but this will take atleast some good amount of CPU.

yeah, thing is, as you know, timer fires interrupt and CPU will
certainly have to service it. So, it's impossible to work around it
IMHO

quoted

are there any ways other than using the kernel timer?

perhaps something less intrusive like creating kernel thread and its
function is solely checking register state?

yes, more or less similar to what the kernel timer does, :)

I think actually when i get the data , i am just copying it to my
local structures,

This job is done in the kernel timer itself, with this itself its
taking a 10% of cpu
which is actually too much.

let me try with softirqs, i am going to use tasklets, what do you think ? :)

--
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

softirqs and tasklets run in interrupt context and must not sleep.
One cannot use copy_from_user() and copy_to_user() in both of them.


Regards

Kshemendra



On Fri, Oct 5, 2012 at 10:24 AM, devendra.aaru [off-list ref]wrote:

On Thu, Oct 4, 2012 at 1:50 PM, Mulyadi Santosa
[off-list ref] wrote:

quoted

Hi...

On Thu, Oct 4, 2012 at 7:03 PM, devendra.aaru [off-list ref]

wrote:

quoted

quoted

Hi all,

I found that you can use a kernel timer and poll for the hardware
interrupt registers whether the interrupt flag is set or not,

but this will take atleast some good amount of CPU.

yeah, thing is, as you know, timer fires interrupt and CPU will
certainly have to service it. So, it's impossible to work around it
IMHO

quoted

are there any ways other than using the kernel timer?

perhaps something less intrusive like creating kernel thread and its
function is solely checking register state?

yes, more or less similar to what the kernel timer does, :)

I think actually when i get the data , i am just copying it to my
local structures,

This job is done in the kernel timer itself, with this itself its
taking a 10% of cpu
which is actually too much.

let me try with softirqs, i am going to use tasklets, what do you think ?
:)

quoted

--
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

_______________________________________________
Kernelnewbies mailing list
Kernelnewbies at kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20121005/2eb1b85b/attachment.html 

Hi Devendra,

     In the kernel thread if you continuously in a loop read a register it
will increase
the CPU usage. After every register read if data is not ready call a
schedule() (or related
call). This may help to reduce CPU utilization

Regards

Kshemendra



On Fri, Oct 5, 2012 at 11:45 AM, Kshemendra KP [off-list ref]wrote:

softirqs and tasklets run in interrupt context and must not sleep.
One cannot use copy_from_user() and copy_to_user() in both of them.


Regards

Kshemendra



On Fri, Oct 5, 2012 at 10:24 AM, devendra.aaru [off-list ref]wrote:

quoted

On Thu, Oct 4, 2012 at 1:50 PM, Mulyadi Santosa
[off-list ref] wrote:

quoted

Hi...

On Thu, Oct 4, 2012 at 7:03 PM, devendra.aaru [off-list ref]

wrote:

quoted

quoted

Hi all,

I found that you can use a kernel timer and poll for the hardware
interrupt registers whether the interrupt flag is set or not,

but this will take atleast some good amount of CPU.

yeah, thing is, as you know, timer fires interrupt and CPU will
certainly have to service it. So, it's impossible to work around it
IMHO

quoted

are there any ways other than using the kernel timer?

perhaps something less intrusive like creating kernel thread and its
function is solely checking register state?

yes, more or less similar to what the kernel timer does, :)

I think actually when i get the data , i am just copying it to my
local structures,

This job is done in the kernel timer itself, with this itself its
taking a 10% of cpu
which is actually too much.

let me try with softirqs, i am going to use tasklets, what do you think ?
:)

quoted

--
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

_______________________________________________
Kernelnewbies mailing list
Kernelnewbies at kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20121005/cab98310/attachment.html 

On Fri, Oct 5, 2012 at 2:32 AM, Kshemendra KP [off-list ref] wrote:

Hi Devendra,

     In the kernel thread if you continuously in a loop read a register it
will increase
the CPU usage. After every register read if data is not ready call a
schedule() (or related
call). This may help to reduce CPU utilization

[please no top posting],

I Know, i didn't say i use copy_from(to)user in the softirqs. its
wrong, and you can use the copy to (from) user in a different context,
ie our fops callbacks.

coming to threads,

these are also one and the same as your timers,

and your threading is wrong, since there is only register read, should
be checking at every 10 - 20 msec,
so coming back to timers :) no?

anyways thanks for letting me know .