iotop like tool for mtd devices

iotop like tool for mtd devices

[Marc Kleine-Budde]

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Hello,

as iotop doesn't work on (NAND) mtd devices, is there a tool, or an API
to query the number of read or written bytes per mtd?

regards,
Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: iotop like tool for mtd devices

[Marc Kleine-Budde]

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On 02/07/2018 02:40 PM, Marc Kleine-Budde wrote:
> as iotop doesn't work on (NAND) mtd devices, is there a tool, or an API
> to query the number of read or written bytes per mtd?

For the record: switching on all the needed kernel config options as
stated in the iotop manpage helps a lot.

sorry for the noise,
Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: iotop like tool for mtd devices

[Marc Kleine-Budde]

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On 02/07/2018 07:21 PM, Marc Kleine-Budde wrote:
> On 02/07/2018 02:40 PM, Marc Kleine-Budde wrote:
>> as iotop doesn't work on (NAND) mtd devices, is there a tool, or an API
>> to query the number of read or written bytes per mtd?
> 
> For the record: switching on all the needed kernel config options as
> stated in the iotop manpage helps a lot.

Update:

The kernel makes the information available at /proc/$$/io. However
"read_bytes" and "write_bytes" seems not to be accurate for mtd devices.

Poking around a bit in the kernel code makes me wonder if some
task_io_account_read(), task_io_account_write() at the right places
would make the accounting better?

Marc

http://lxr.bootlin.com/linux/latest/ident/task_io_account_read
http://lxr.bootlin.com/linux/latest/ident/task_io_account_write

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: iotop like tool for mtd devices

[Richard Weinberger]

Marc,

On Wed, Feb 7, 2018 at 8:31 PM, Marc Kleine-Budde <mkl@pengutronix.de> wrote:
> On 02/07/2018 07:21 PM, Marc Kleine-Budde wrote:
>> On 02/07/2018 02:40 PM, Marc Kleine-Budde wrote:
>>> as iotop doesn't work on (NAND) mtd devices, is there a tool, or an API
>>> to query the number of read or written bytes per mtd?
>>
>> For the record: switching on all the needed kernel config options as
>> stated in the iotop manpage helps a lot.
>
> Update:
>
> The kernel makes the information available at /proc/$$/io. However
> "read_bytes" and "write_bytes" seems not to be accurate for mtd devices.
>
> Poking around a bit in the kernel code makes me wonder if some
> task_io_account_read(), task_io_account_write() at the right places
> would make the accounting better?

I'd guess so.
One thing we need to consider are stacked MTDs, here the accounting
should not happen multiple times.