On Mon, Apr 24, 2017 at 9:26 AM, Jeff Moyer <jmoyer@xxxxxxxxxx> wrote: > Dan Williams <dan.j.williams@xxxxxxxxx> writes: > >> The nvdimm_flush() mechanism helps to reduce the impact of an ADR >> (asynchronous-dimm-refresh) failure. The ADR mechanism handles flushing >> platform WPQ (write-pending-queue) buffers when power is removed. The >> nvdimm_flush() mechanism performs that same function on-demand. >> >> When a pmem namespace is associated with a block device, an >> nvdimm_flush() is triggered with every block-layer REQ_FUA, or REQ_FLUSH >> request. However, when a namespace is in device-dax mode, or namespaces >> are disabled, userspace needs another path. >> >> The new 'flush' attribute is visible when it can be determined that the >> interleave-set either does, or does not have DIMMs that expose WPQ-flush >> addresses, "flush-hints" in ACPI NFIT terminology. It returns "1" and >> flushes DIMMs, or returns "0" the flush operation is a platform nop. >> >> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > > NACK. This should function the same way it does for a pmem device. > Wire up sync. We don't have dirty page tracking for device-dax, without that I don't think we should wire up the current sync calls. I do think we need a more sophisticated sync syscall interface eventually that can select which level of flushing is being performed (page cache vs cpu cache vs platform-write-buffers). Until then I think this sideband interface makes sense and sysfs is more usable than an ioctl. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
