Re: [PATCH] fio: add NVMe engine

[Alexey Dobriyan <adobriyan@gmail.com>]

On Thu, Mar 26, 2020 at 04:05:08PM -0600, Jens Axboe wrote:
> On 3/26/20 2:44 PM, Alexey Dobriyan wrote:
> > Add simple iodepth=1 NVMe engine:
> > 
> > 	ioengine=nvme
> > 
> > It works via standard Linux NVMe ioctls.
> > 
> > It will be used for testing upcoming ZNS stuff.
> > 
> > Currently Linux doesn't recognize NVMe ZNS devices as zoned block
> > devices so zone ioctls (BLKRESETZONE et al) can't be used.
> > 
> > Passthrough ioctls should allow Zone Append and whatever commands
> > new specs bring.
> > 
> > Support read, write, fsync, fdatasync.
> > Don't support sync_file_range obviously.
> > Don't support trim for now, until I figure all qemu options and
> > the story behind broken qemu trim support.
> 
> Needs a bit of cleanup, but otherwise simple enough. A few comments:
> 
> > +static inline uint32_t get_nsid(const struct fio_file *f)
> > +{
> > +	return (uintptr_t)f->engine_data;
> > +}
> 
> You could pack both nsid and lba_shift in there, and maybe use
> engine_pos instead to avoid the cast.

lba_shift should be generic (live in struct fio_file). Maybe something
else will use it. If my zone fix goes in then 2 64-bit divisions can be
simplified!

> > +static int fio_nvme_read(struct fio_file *f, struct io_u *io_u)
> > +{
> > +	fio_unused uint32_t nsid = get_nsid(f);
> > +	struct nvme_user_io cmd = {};
> > +
> > +	//printf("R %u %llu/%llu\n", nsid, io_u->offset, io_u->xfer_buflen);
> 
> Leftover debug

dprint(FD_IO is pretty chatty, but OK.

> 
> > +static int fio_nvme_write(struct fio_file *f, struct io_u *io_u)
> > +{
> > +	fio_unused uint32_t nsid = get_nsid(f);
> > +	struct nvme_user_io cmd = {};
> > +
> > +	//printf("W %u %llu/%llu\n", nsid, io_u->offset, io_u->xfer_buflen);
> 
> Ditto
> 
> > +static int fio_nvme_flush(struct fio_file *f)
> > +{
> > +	uint32_t nsid = get_nsid(f);
> > +	struct nvme_passthru_cmd cmd = {};
> > +
> > +	//printf("F %u\n", nsid);
> 
> Ditto