Re: submit_bh leaves interrupts on upon return

[Jeff V. Merkey]

Linus Torvalds wrote:

> On Thu, 3 Jun 2004, Jens Axboe wrote:
>
>  
>
> > On Thu, Jun 03 2004, Jeff V. Merkey wrote:
> >    
> >
> > > Sounds like I need to move to 2.6. I noticed the elevator is coalescing 
> > > quite well, and since I am posting mostly continguous runs of sectors, 
> > > what ends up at the adapter level would probably not change much much 
> > > between 2.4 and 2.6 since I am maxing out the driver request queues as 
> > > it is (255 pending requests of 32 scatter/gather elements of 256 sector 
> > > runs). 2.6 might help but I suspect it will only help alleviate the 
> > > submission overhead, and not make much difference on performance since 
> > > the 3Ware card does have an upward limit on outstanding I/O requests.
> > >      
> > That's correct, it just helps you diminish the submission overhead by
> > pushing down 256 sector entities in one go. So as long as you're io
> > bound it won't give you better io performance, of course. If you are
> > doing 400MiB/sec it should help you out, though.
> >    
>
> Well, if Jeff does almost exclusively contiguous stuff and submits them in
> order, then the coalescing will make sure that even on 2.4.x the queues
> don't get too long, and he probably won't see the pathological cases.
>
> 		Linus
> -
Linus,

This seems to be the case.

Jeff




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