Re: WAPBL vs. lfs?

[Thor Lancelot Simon <tls%rek.tjls.com@localhost>]

On Mon, Aug 25, 2008 at 05:32:26PM +0200, Joerg Sonnenberger wrote:
> On Mon, Aug 25, 2008 at 11:20:33AM -0400, Thor Lancelot Simon wrote:
> > Regardless of the details (about which I believe you're mistaken) it is
> > still the case that, writing a continuous stream of directory or small
> > file creations, WAPBL does less than half the maximum throughput of the
> > underlying drive, while LFS can get close to 100% and is generally well
> > above 75%.  In normal operation there are no "dependency cycles" to break
> > in LFS.
> 
> I'm not arguing relative to LFS. The comment was entirely about the
> second part, comparing WAPBL with plain UFS or softdep.

The real fix for the "writes metadata twice" issue is to support a journal
on another partition.  With a real SSD (that is, one that's not built from
flash memory with its insane write penalty) this would make the extra
writes almost free.

-- 
Thor Lancelot Simon                                        
tls%rek.tjls.com@localhost
 "My guess is that the minimal training typically provided would only
 have given the party in question multiple new and elaborate ways to do
 something incomprehensibly stupid and dangerous."      -Rich Goldstone