Re: [Yaffs] multithreading question

Very nice! We will try to integrate it in time. Thanks a lot for fast
response!

Regards
Johan

----- Original Message -----
From: "Charles Manning" <manningc2@actrix.gen.nz>
To: <yaffs@lists.aleph1.co.uk>
Cc: "Johan Kotlinski" <johan@teenageengineering.com>
Sent: Friday, February 05, 2010 5:05 AM
Subject: Re: [Yaffs] multithreading question


> On Wednesday 03 February 2010 23:17:42 Johan Kotlinski wrote:
>> Hi Charles!
>>
>> Thanks for your answer. Yes, I was talking about yaffs direct.
>> Page-by-page
>> locking is of course all right.
>>
>> I have another question. Our NAND chip has the ability to prefetch pages.
>> I
>> imagine we could benefit from this. Is there a way to get a hint from
>> yaffs
>> what it is about to read next? Or do you know some good place to insert
>> such an optimization?
>>
>> Best regards,
>> Johan
>>
> I have just checked in code which breaks up long reads and writes into
> smaller
> sub read/writes.
>
> This has the advantage of reducing longing times.
>
> Please give this a whirl if it is of interest to you.
>
> -- Charles
>
> > ----- Original Message -----
>> From: "Charles Manning" <manningc2@actrix.gen.nz>
>> To: <yaffs@lists.aleph1.co.uk>
>> Cc: "Johan Kotlinski" <johan@teenageengineering.com>
>> Sent: Wednesday, February 03, 2010 1:15 AM
>> Subject: Re: [Yaffs] multithreading question
>>
>> > On Tuesday 02 February 2010 00:29:17 Johan Kotlinski wrote:
>> >> Hi!
>> >> It appears that Yaffs2 multithreading protection is on a very high
>> >> level
>> >> (mutex wrapping entire fread/fwrite calls).
>> >
>> > Are you talking about yaffs direct or the Linux yaffs?
>> > The linux yaffs will be locked on a page-by-page basis and I am going
>> > to
>> > change the way yaffs direct does the reading/writing too to only lock
>> > on
>> > a page-by-page basis.
>> >
>> > The underlying NAND is locked on a apge by page basis too (that's a
>> > limitation
>> > of the hardware), so is this really a big concern?
>> >
>> >> My worry is that if a low-priority task does a large fwrite call, it
>> >> could
>> >> block high-priority tasks for a long time. Is this an acknowledged
>> >> problem?
>> >
>> > It depends on the OS. Some, without priority inhere, won't have this
>> > problem.
>> >
>> >> Are there comparable file systems that handle multithreading in a more
>> >> granular way?
>>
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>
>