On Tue, Jan 17, 2017 at 10:01:30PM -0800, Dan Williams wrote: > >> - Jan suggested [2] that we could use the radix tree as a cache to service DAX > >> faults without needing to call into the filesystem. Are there any issues > >> with this approach, and should we move forward with it as an optimization? > > > > Ahem. I believe I proposed this at last year's LSFMM. And I sent > > patches to start that work. And Dan blocked it. So I'm not terribly > > amused to see somebody else given credit for the idea. > > I "blocked" moving the phys to virt translation out of the driver > since that mapping lifetime is device specific. The problem is that DAX currently assumes that there *is* a block driver, and it might be a char device or no device at all (the two examples I gave earlier). > However, I think caching the file offset to physical sector/address > result is a great idea. OK, great. The lifetime problem I think you care about (hotplug) can be handled by removing all the cached entries for every file on every file on that block device ... I know there were prototype patches for that; did they ever get merged? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>