Re: [PATCH][RFC] Fix "two RAID1 mirrors are faster than three"

On Monday May 12, 76306.1226@compuserve.com wrote:

  This patch is only lightly tested on 2.4.21-rc2-ac1.

  It attempts to speed up single sequential streaming reads as well as
fixing the problem with multiple streams not working on 3+ disk
mirrors.  With this patch applied I get full speed form all three
disks when reading three streams at once.

  A version of this on 2.4.20aa1 gives about 60% performance gains on single
sequential streams but it yields effectively no gain on stock kernels (?)
I've given up trying to figure out why...

  How much of this is worth merging?  (One line has already been
  rejected.)

Hard to say.  As you mentioned in another email, it changes too much
stuff.

Either split it into logic bits, or explain in detail what it is
trying to achieve, or both, and I will tell you what I think.

NeilBrown