[Yaffs] Re: CONFIG_YAFFS_USE_GENERIC_RW

[Wookey]

+++ Charles Manning [04-10-14 12:12 +1300]:
> This is a historic thing.
> USE_GENERIC_RW uses the Linux page cache for read/write. This means that the Linux generic_read and generic_write functions are used which and YAFFS supplies the read_page write_page calls.
> 
> Not defining USE_GENERIC_RW directly implements read/write without using the page cache.
> 
> The direct read/write stuff was iimplemented first, and I followed it by generic read/write when memory mapping was implemented. During the transition both options worked. Things have now moved on and not defining USE_GENERIC_RW is broken, with no real motivation to fix it. 
> 
> Ie. You should always define USE_GENERIC_RW. 
> 
> This comes up every couple of months on the list. I guess I should pull it out.

We did find one person who found that it was useful to avoid the cache as it
gave them a significant speedup in their fairly pathological use-case, as I recall.

Maybe what we need is some better docs about what the various defines do and
when you would want to use them....

There has been a lot of useful info on this list in the last couple of weeks
- it just needs collecting together and putting on the web/in the docs.

I've been meaning to updatethe docs for a while - but if anyone else feels
enthused....

Wookey
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