[PATCH] xfs_repair: multithread phase 2

[Michael Monnerie]

On Montag, 10. Januar 2011 Dave Chinner wrote:
> Pretty much
> every sata disk supports NCQ these days, and default to a depth of
> 32, which means we can have 32 concurrent reads in progress at once.
> Phase 2 is all synchronous IO, so the only way to hide the IO
> latency is to queue work to multiple threads and switch between the
> threadsto work on another queue when the current one blocks waiting
> for IO.

This is interesting. Did you measure this with a rotating single disk? 
Is the idle time between two synchronous reads bigger than the time 
needed to move the disk head to another cylinder and read a sector? That 
takes ~15ms on a normal disk, incredibly long compared to cpu speed. 
Even with NCQ, the disk would have to swing the head a lot, and just 
from thinking about it I wouldn't believe that it's faster like this.

But I'm sure you tested it so I take it as given that it's like that. 
Cool improvement, btw :-)

-- 
mit freundlichen Grüssen,
Michael Monnerie, Ing. BSc

it-management Internet Services: Protéger
http://proteger.at [gesprochen: Prot-e-schee]
Tel: +43 660 / 415 6531

// ****** Radiointerview zum Thema Spam ******
// http://www.it-podcast.at/archiv.html#podcast-100716
// 
// Haus zu verkaufen: http://zmi.at/langegg/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 198 bytes
Desc: This is a digitally signed message part.
URL: <http://oss.sgi.com/pipermail/xfs/attachments/20110110/8f7bd908/attachment.sig>