Hi All

This week has been good for speeding up yaffs. All cchanges mentioned here are 
now in cvs.

As mentioned earlier this week, the dynamic updating of the oldest dirty 
sequence number sped up writes  by up to 30% for one cell phone platform.

Then there was the addition of background processing for dirty directory 
handling. That can reduce the writes associated with small file 
creation/deletion by a significant amount meaning less garbage collection and 
faster performance.

Today has seen two further check ins that give speed ups:

A) Phase 1 of reduction of shrink headers

Shrink headers are no longer written when files are resized down or 
overwritten. This can significantly reduce the number of shrink headers which 
can really make a big difference to garbage collection speed. Shrink headers 
are still written when files are resized up by large amounts or when a file 
is deleted. One particular scenario that this helps is where files are opened 
for write with O_TRUNC and completely overwritten. eg.
#cp a foo
#cp b foo
That would have created a shrink header in the past but no longer does.

B) Better block iteration
There are some code sequences that iterated over all blocks and called the 
yaffs_GetBlockInfo() function. These now just use direct block iteration 
which is way faster. The difference will likely not be anything as dramatic 
as other improvements, but it is there.

All my test harnesses will be running for the whole week end to give these 
changes a thorough work out.

Friday afternoon here... time to go fishing.

-- Charles