Hi, Christoph, Christoph Hellwig <[email protected]> writes:
> On Tue, Aug 01, 2023 at 11:23:36AM -0400, Jeff Moyer wrote: >> I am slightly embarrassed to have to ask this question, but what are the >> implications of setting this queue flag? Is the submit_bio routine >> expected to never block? > > Yes, at least not significantly. If there happens to be poisoned memory, the write path can make an acpi device specific method call. That involves taking a mutex (see the call chain starting at acpi_ex_enter_interpreter()). I'm not sure how long a DSM takes, but I doubt it's fast. >> Is the I/O expected to be performed >> asynchronously? > > Not nessecarily if it is fast enough.. Clear as mud. :) It's a memcpy on potentially "slow" memory. So, the amount of time spent copying depends on the speed of the cpu, the media and the size of the I/O. I don't know off-hand what the upper bound would be on today's pmem. -Jeff
