Messages in this thread | | | Date | Sat, 11 Apr 2009 18:15:36 -0700 (PDT) | From | david@lang ... | Subject | Re: Implementing NVMHCI... |
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On Sun, 12 Apr 2009, Alan Cox wrote:
>> We've abstract the DMA mapping/SG list handling enough that the >> block size should make no more difference than it does for the >> MTU size of a network. > > You need to start managing groups of pages in the vm and keeping them > together and writing them out together and paging them together even if > one of them is dirty and the other isn't. You have to deal with cases > where a process forks and the two pages are dirtied one in each but still > have to be written together.
gaining this sort of ability would not be a bad thing. with current hardware (SSDs and raid arrays) you can very easily be in a situation where it's much cheaper to deal with a group of related pages as one group rather than processing them individually. this is just an extention of the same issue.
David Lang
> Alternatively you go for read-modify-write (nasty performance hit > especially for RAID or a log structured fs). > > Yes you can do it but it sure won't be pretty with a conventional fs. > Some of the log structured file systems have no problems with this and > some kinds of journalling can help but for a typical block file system > it'll suck. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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