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Re: WAPBL vs. lfs?

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                               
 "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

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