On Thu, Apr 26 2007, Christoph Lameter wrote: > On Thu, 26 Apr 2007, Eric W. Biederman wrote: > > > I can't possibly believe any of this is about the cost of processing > > a request, but rather the problem that some devices don't have a large > > enough pool of requests to keep them busy if you submit the requests > > in a 4K page sizes. > > > > This all sounds like a device design issue rather than anything more > > significant, and it doesn't sound like a long term trend. Market > > pressure should fix the hardware. > > Sounds like we are dictating device manufacturers how to > design their devices instead of leaving them choice.
Well... First of all (to Eric), the 4kb pages isn't the issue. Only if you have limited sg capabilities in your hardware AND need larger segment sizes to get up in the range of request sizes that makes that hardware go fast would you benefit from always using bigger pages. And market pressure should indeed make you lose, if you design crappy hardware like that. Secondly, choice isn't always good. Linux should cater to the hardware only to the extent that it makes sense. We don't make design decisions that are unmaintainable or cripple us in some way because of bad hardware. That would be stupid. If we need and want larger IO sizes, then we can do that without big compound pages. I'm merely interested in the bigger page cache pages because it'll solve several issues at once. -- 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/
