Re: [Yaffs] Periodic Checkpointing

> -----Original Message-----
> From: yaffs-bounces@lists.aleph1.co.uk [mailto:yaffs-
> bounces@lists.aleph1.co.uk] On Behalf Of Charles Manning
> Sent: Thursday, 1 April 2010 10:04 AM
> To: yaffs@lists.aleph1.co.uk
> Subject: Re: [Yaffs] Periodic Checkpointing
>
...
> Another approach that I keep mentioning, and should really get around
to
> doing, is implementing "block summaries". This would use the last
chunk in
> each block to hold all the tags for chunks in the block. That makes
> scanning
> way, way, faster meaning that the fallback for handling the case when
> there
> is no current checkpoint is still approaches checkpoint speed.
>

Wouldn't this only be a gain for the inband-tags case, or when the MTD
driver can't read out a page's tags without reading out the entire page
as well (as some hardware ECC forces you to do)?

It would be interesting if this also let you save chunk
deletion/obsoletion flags - I heard someone pondering an
"incremental/background mount" idea once, where more files would become
available as the scan progressed. (Of course, any readdir() or access to
a non-existent file would have to block until the scan finished... but
with a usual layout, it might get init started a couple of seconds
earlier.) The biggest catch would be making sure old data (old
filenames, deleted files, old contents) weren't temporarily resurrected.

J