Messages in this thread | | | Date | Fri, 02 May 2008 22:09:51 +0400 | From | Vladislav Bolkhovitin <> | Subject | Re: [PATCH 2.6.25.1] Add scsi_execute_async_fifo() |
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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@infradead.org> 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
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