* Priority inversion when using MTD
@ 2007-05-17 13:20 Sekhar Nori
2007-05-17 13:52 ` David Woodhouse
0 siblings, 1 reply; 3+ messages in thread
From: Sekhar Nori @ 2007-05-17 13:20 UTC (permalink / raw)
To: linux-mtd
Hi,
I have a high priority SCHED_FIFO task which runs out of a squashfs file system.
When this process needs to fetch a page from the flash (due to demand paging),
it is sometimes made to wait for another low priority SCHED_NORMAL
task which is doing an erase on some other mtd partition.
This helps other middle priority processes have a free run causing a
priority inversion issue.
The get_chip function in cfi_cmdset_0001.c uses a per chip wait queue
for all processes which need to wait for chip access.
Is there any way to avoid this scenario? Any help/pointers would be appreciated.
Thanks,
Sekhar Nori.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Priority inversion when using MTD
2007-05-17 13:20 Priority inversion when using MTD Sekhar Nori
@ 2007-05-17 13:52 ` David Woodhouse
2007-05-17 16:36 ` Sekhar Nori
0 siblings, 1 reply; 3+ messages in thread
From: David Woodhouse @ 2007-05-17 13:52 UTC (permalink / raw)
To: Sekhar Nori; +Cc: linux-mtd
On Thu, 2007-05-17 at 18:50 +0530, Sekhar Nori wrote:
> I have a high priority SCHED_FIFO task which runs out of a squashfs file system.
> When this process needs to fetch a page from the flash (due to demand paging),
> it is sometimes made to wait for another low priority SCHED_NORMAL
> task which is doing an erase on some other mtd partition.
...
> Is there any way to avoid this scenario? Any help/pointers would be appreciated.
mlockall(2)
--
dwmw2
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Priority inversion when using MTD
2007-05-17 13:52 ` David Woodhouse
@ 2007-05-17 16:36 ` Sekhar Nori
0 siblings, 0 replies; 3+ messages in thread
From: Sekhar Nori @ 2007-05-17 16:36 UTC (permalink / raw)
To: David Woodhouse; +Cc: linux-mtd
On 5/17/07, David Woodhouse <dwmw2@infradead.org> wrote:
> On Thu, 2007-05-17 at 18:50 +0530, Sekhar Nori wrote:
> > I have a high priority SCHED_FIFO task which runs out of a squashfs file system.
> > When this process needs to fetch a page from the flash (due to demand paging),
> > it is sometimes made to wait for another low priority SCHED_NORMAL
> > task which is doing an erase on some other mtd partition.
> ...
> > Is there any way to avoid this scenario? Any help/pointers would be appreciated.
>
> mlockall(2)
But doing so for all SCHED_FIFO tasks would make the system run out of memory :(
-
Sekhar Nori
^ permalink raw reply [flat|nested] 3+ messages in thread
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2007-05-17 13:20 Priority inversion when using MTD Sekhar Nori
2007-05-17 13:52 ` David Woodhouse
2007-05-17 16:36 ` Sekhar Nori
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