Re: [PATCH 2.6.25.1] Add scsi_execute_async_fifo()

[Vladislav Bolkhovitin]

James Bottomley wrote:
> On Fri, 2008-05-02 at 18:06 +0200, Bart Van Assche wrote:
> > On Fri, May 2, 2008 at 5:55 PM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
> > > On Fri, May 02, 2008 at 05:53:22PM +0200, Bart Van Assche wrote:
> > > > Regarding out-of-tree modules: this is just a preparatory step before
> > > > submitting SCST for inclusion in the mainstream kernel.
> > > And what crackpipe did you smoke to thing we'd put duplicated target
> > > framework in?
> > Why are you so aggressive ? I didn't insult you in any way.
> >
> > Regarding inclusion of SCSI target code in the mainline, this subject
> > has already been discussed extensively in the past
> > (http://lkml.org/lkml/2008/1/23/134). The conclusion was clear: SCST
> > is faster than any other existing iSCSI target for Linux (IET, STGT,
> > LIO), stable, well maintained and the most standards compliant target.
> > Why do you want to reopen this discussion ?
>
> That's an interesting rewrite of history.  The evidence you presented
> showed fairly identical results apart from on one contrived IB benchmark
> that couldn't directly compare the two.
>
> I'm also on record in the thread saying that was insufficient proof for
> me to justify throwing STGT out and replacing it with SCST.

James, why do you keep ignoring important points, written by me in that 
e-mail: http://lkml.org/lkml/2008/1/30/178?

Namely:

1. Solid architecture of SCST is inherently more simple than distributed 
user/kernel space processing, when kernel behaves under control of user 
space, used in STGT, and allows to get better results with less effort. 
Better in all aspects: simplicity (hence, maintainability), reliability 
and performance. Linux once made step away from microkernel based design 
and that was for really good reasons.

2. Zero-copy operations with page cache will halve processing latency on 
high speed links, like InfiniBand, and it is impossible to implement 
that in a sane way with STGT approach, while for SCST it can be 
implemented simply and naturally.

Vlad

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/