[Yaffs-archive] Re: [YAFFS] slow performance --> Cache enabl…

Top Page
Attachments:
Message as email
+ (text/plain)
Delete this message
Reply to this message
Author: Charles Manning
Date:  
To: Sam Mason
CC: Edward J. Lee, yaffs
Subject: [Yaffs-archive] Re: [YAFFS] slow performance --> Cache enabling
On Thursday 01 May 2003 21:49, Sam Mason wrote:
> Charles Manning wrote:
> >Edward's feedback was a big suprise to me as I would have expected the
> > Linux cache to have done the job more effectively that the YAFFS cache.
>
> I guess I'm showing my ignorance here. . . I've just had a quick look
> though the code, and it seems as though it doesn't need to use the
> Linux page cache.


By default configuration YAFFS uses (or at least should be) generic_file_read
and generic_file_write which use the Linux page cache for caching. This can
be controlled by disabling CONFIG_YAFFS_USE_GENERIC_RW. If this caching is
disabled (due to changing the config or a bug in the way I wrote the code),
then using the in-YAFFS cache would provide a dramatic speedup.

What would suprise me is getting the speed increase by using both caches
since I would expect the Linux page cache to effectively render the YAFFS
cache useless.

>
> I presume that this has been discounted already. But, I just know how
> many times I've spent days tracking down bugs, only to notice that
> some assumption I was making, was bogus.


Yes, I did make some assumptions that maybe were invalid. Thanx for pointing
them out Sam.

-- Charles



---------------------------------------------------------------------------------------
This mailing list is hosted by Toby Churchill open software (www.toby-churchill.org).
If mailing list membership is no longer wanted you can remove yourself from the list by
sending an email to with the text "unsubscribe"
(without the quotes) as the subject.