On Fri, Apr 27 2007, Nick Piggin wrote: > Why do we limit drivers to 128 sg entries?
No particular reason, except than to avoid 2^bigger order allocations. 2MiB requests would require 3 contig pages to setup the sg list, which is (probably) a little troublesome especially since it's sometimes atomically allocated. Larger pages are by no means a prerequisite to getting larger requests, assuming your hardware can handle the bigger sglist. There are other ways of doing that, I've contemplated doing chained sglists and adding sg_for_each_segment() macros for iterating these things. Drivers that want larger sglists would then be required to update their sg mapping loop to use the provided macros. It wouldn't be too hard. -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
