re: biowait for seconds

[matthew green <mrg%eterna23.net@localhost>]

Thor Lancelot Simon writes:
> On Fri, Apr 18, 2025 at 11:38:35AM +0200, Edgar Fu? wrote:
> > I guess you may need to convert the driver to use MSI.
>
> Does nVME even support non-MSI interrupts?  Given its overall design that
> would be surprising to me.

yes, it works, but it is limiting in this case.  eg, you need
MSI or MSI-X to get per-cpu vectors.  nvme_pci.c has these
things that we don't really provide as tuneables except by
editing the code itself, but look at what these do:

int nvme_pci_force_intx = 0;
int nvme_pci_mpsafe = 1;
int nvme_pci_mq = 1;            /* INTx: ioq=1, MSI/MSI-X: ioq=ncpu */


i had to set nvme_pci_force_intx=1 on a 32-cpu system with
4 nvmes to get the 4th one to attach, otherwise we ran out
of interrupts.


.mrg.