|To:||Dave Chinner <david@xxxxxxxxxxxxx>|
|Subject:||Re: in 3.7 kernel, how does 1GB page tables for kernel pagetables affect XFS?|
|From:||Linda Walsh <xfs@xxxxxxxxx>|
|Date:||Sat, 19 Jan 2013 15:55:17 -0800|
|User-agent:||Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:220.127.116.11) Gecko/20100228 Lightning/0.9 Thunderbird/18.104.22.168 Mnenhy/0.7.6.666|
Dave Chinner wrote:
On Sat, Jan 19, 2013 at 11:47:44AM -0800, Linda Walsh wrote:Given that XFS relies on the page size for it's maximum block size, does switching to 1GB pages for kernel pagetables allow for larger page-size use in XFS -- and therefore, larger blocksize?No, it doesn't. The page cache can't use large pages so there's no path to allowing XFS to use larger blocks with them. As it is, you'd need a system that supports 16k or 64k page sizes for this to be useful, otherwise you just waste a *lot* of memory...Is it something that might be in the not too distant future? ;-)I have no plans to do this any time soon - there's no compelling reason to do so. I can't speak for anyone else, though...
--- No prob.. I admit a 1GB page size might be a tad large for my purposes... I actually was reading 1MB though even that would be large...but a GB/disk sector...um...-- at least I'd be likely to get full speed read & writes if I could fill them...(1GB/R or W gives me about the fastest overall throughput to my disks). Can't test higher (i.e. >=2GB) than that due to getting partial block read/writes (on a 64 bit machine??) Sounds like my LSI controller is only 32bits...but that doesn't seem right... Maybe it only supports consecutive read/writes up to the limit of the memory on the controller card.. All that talk about RAIDs recently, got me depressed a bit when I realize that while I can get fast speeds, type speeds in seeking around are about 1/10-1/20th the speed...sigh. Might that indicate that I should go with smaller RAIDS with more spindles? I.e. instead of 3 groups of RAID5 striped as 0, go for 4-5 groups of RAID5 striped as a 0? Just aligning the darn things nearly takes a rocket scientist! But then start talking about multiple spindles and optimizing IOP's...ARG!...;-) (If it wasn't challenging, I'd find it boring...)...
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