Dan Williams <dan.j.williams@xxxxxxxxx> writes: > On Mon, May 7, 2018 at 11:46 AM, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: >> On Mon, May 07, 2018 at 10:50:21PM +0800, Huaisheng Ye wrote: >>> Traditionally, NVDIMMs are treated by mm(memory management) subsystem as >>> DEVICE zone, which is a virtual zone and both its start and end of pfn >>> are equal to 0, mm wouldn’t manage NVDIMM directly as DRAM, kernel uses >>> corresponding drivers, which locate at \drivers\nvdimm\ and >>> \drivers\acpi\nfit and fs, to realize NVDIMM memory alloc and free with >>> memory hot plug implementation. >> >> You probably want to let linux-nvdimm know about this patch set. >> Adding to the cc. > > Yes, thanks for that! > >> Also, I only received patch 0 and 4. What happened >> to 1-3,5 and 6? >> >>> With current kernel, many mm’s classical features like the buddy >>> system, swap mechanism and page cache couldn’t be supported to NVDIMM. >>> What we are doing is to expand kernel mm’s capacity to make it to handle >>> NVDIMM like DRAM. Furthermore we make mm could treat DRAM and NVDIMM >>> separately, that means mm can only put the critical pages to NVDIMM Please define "critical pages." >>> zone, here we created a new zone type as NVM zone. That is to say for >>> traditional(or normal) pages which would be stored at DRAM scope like >>> Normal, DMA32 and DMA zones. But for the critical pages, which we hope >>> them could be recovered from power fail or system crash, we make them >>> to be persistent by storing them to NVM zone. [...] > I think adding yet one more mm-zone is the wrong direction. Instead, > what we have been considering is a mechanism to allow a device-dax > instance to be given back to the kernel as a distinct numa node > managed by the VM. It seems it times to dust off those patches. What's the use case? The above patch description seems to indicate an intent to recover contents after a power loss. Without seeing the whole series, I'm not sure how that's accomplished in a safe or meaningful way. Huaisheng, could you provide a bit more background? Thanks! Jeff
