Messages in this thread |  | | From | Neil Brown <> | Date | Tue, 5 Sep 2000 11:59:30 +1100 (EST) | Subject | Re: [PATCH] 2.4.0-test7 to Enable Variable Block Chaining |
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On Saturday September 2, jmerkey@timpanogas.com wrote: > > Linus, > > The attached patch is submitted to enable variable sector size block > chaining via ll_rw_block() in the I/O subsystem layer. > > Jeff904a905,907 > > /**** > > // This code is being commented out to allow support for variable chained > > // block I/O requests. Jeff V. Merkey > 915a919 > > *****/
While I think this patch is a good idea, I feel I should let you know that using the functionality on a Software-RAID-5 device will cause terrible performance. Whenever raid5.c notices the block size has changed, it flushes it's stripe cache, and rebuilds it with the new size. This effectively serialises requests around any size change.
Fixing this in on my todo list, but I haven't come up with a really neat model yet.
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