here's a diff to sys/arch/sparc/dev/fd.c. not compiled, and therefore
not tested.
anyone? ok?
On Sun, Nov 03, 2013 at 09:30:56AM +1000, David Gwynne wrote:
> once upon a time pretty much all block storage was on spinning disks, so all
> the drivers for disks tried to order queued io to better suit moving a head
> across a platter by calling disksort. between then and now a lot of the
> assumptions that disksort relied on are no longer true (eg, SSDs are a thing
> now) so it's usually more harmful than helpful. with beck@s addition of the
> nscan backend in bufqs it makes sense to try and unify all disk drivers
> behind bufqs and deprecate disksort.
>
> so, ive been working through the tree replacing the last direct users of the
> disksort() over to bufqs, but ive run out of code that i can compile for.
> there are now 4 drivers in 3 architectures that need conversion, so im asking
> if anyone is interested in taking some (or all) of them on.
>
> the code in question is:
>
> sys/arch/hp300/dev/hd.c
> sys/arch/sparc/dev/fd.c
> sys/arch/sparc/dev/xy.c
> sys/arch/vax/vsa/hdc9224.c
>
> if anyone has those archs and a some spare time, please feel free to have a
> go and cut them over. even if you dont have the hardware to test your change,
> making a compilable diff and sending it to tech@ for testing is better than i
> can do right now.
>
> cheers,
> dlg
Index: fd.c
===================================================================
RCS file: /cvs/src/sys/arch/sparc/dev/fd.c,v
retrieving revision 1.86
diff -u -p -r1.86 fd.c
--- fd.c 12 Nov 2013 16:04:09 -0000 1.86
+++ fd.c 17 Nov 2013 06:40:34 -0000
@@ -217,7 +217,8 @@ struct fd_softc {
TAILQ_ENTRY(fd_softc) sc_drivechain;
int sc_ops; /* I/O ops since last switch */
- struct buf sc_q; /* head of buf chain */
+ struct bufq sc_bufq; /* pending I/O requests */
+ struct buf *sc_bp; /* current I/O */
struct timeout fd_motor_on_to;
struct timeout fd_motor_off_to;
@@ -642,6 +643,7 @@ fdattach(parent, self, aux)
*/
fd->sc_dk.dk_flags = DKF_NOLABELREAD;
fd->sc_dk.dk_name = fd->sc_dv.dv_xname;
+ bufq_init(&fd->sc_bufq, BUFQ_DEFAULT);
disk_attach(&fd->sc_dv, &fd->sc_dk);
/*
@@ -732,11 +734,13 @@ fdstrategy(bp)
(long long)fd->sc_blkno, bp->b_cylinder);
#endif
+ /* Queue transfer */
+ bufq_queue(&fd->sc_bufq, bp);
+
/* Queue transfer on drive, activate drive and controller if idle. */
s = splbio();
- disksort(&fd->sc_q, bp);
timeout_del(&fd->fd_motor_off_to); /* a good idea */
- if (!fd->sc_q.b_active)
+ if (fd->sc_bp == NULL)
fdstart(fd);
#ifdef DIAGNOSTIC
else {
@@ -767,7 +771,7 @@ fdstart(fd)
int active = !TAILQ_EMPTY(&fdc->sc_drives);
/* Link into controller queue. */
- fd->sc_q.b_active = 1;
+ fd->sc_bp = bufq_dequeue(&fd->sc_bufq);
TAILQ_INSERT_TAIL(&fdc->sc_drives, fd, sc_drivechain);
/* If controller not already active, start it. */
@@ -782,6 +786,9 @@ fdfinish(fd, bp)
{
struct fdc_softc *fdc = (void *)fd->sc_dv.dv_parent;
+ fd->sc_skip = 0;
+ fd->sc_bp = bufq_dequeue(&fd->sc_bufq);
+
/*
* Move this drive to the end of the queue to give others a `fair'
* chance. We only force a switch if N operations are completed while
@@ -791,15 +798,11 @@ fdfinish(fd, bp)
if (TAILQ_NEXT(fd, sc_drivechain) != NULL && ++fd->sc_ops >= 8) {
fd->sc_ops = 0;
TAILQ_REMOVE(&fdc->sc_drives, fd, sc_drivechain);
- if (bp->b_actf) {
+ if (fd->sc_bp != NULL)
TAILQ_INSERT_TAIL(&fdc->sc_drives, fd, sc_drivechain);
- } else
- fd->sc_q.b_active = 0;
}
- bp->b_resid = fd->sc_bcount;
- fd->sc_skip = 0;
- fd->sc_q.b_actf = bp->b_actf;
+ bp->b_resid = fd->sc_bcount;
biodone(bp);
/* turn off motor 5s from now */
timeout_add_sec(&fd->fd_motor_off_to, 5);
@@ -1117,7 +1120,7 @@ fdctimeout(arg)
goto out;
}
- if (fd->sc_q.b_actf)
+ if (fd->sc_bp != NULL)
fdc->sc_state++;
else
fdc->sc_state = DEVIDLE;
@@ -1285,11 +1288,10 @@ loop:
}
/* Is there a transfer to this drive? If not, deactivate drive. */
- bp = fd->sc_q.b_actf;
+ bp = fd->sc_bp;
if (bp == NULL) {
fd->sc_ops = 0;
TAILQ_REMOVE(&fdc->sc_drives, fd, sc_drivechain);
- fd->sc_q.b_active = 0;
goto loop;
}
@@ -1663,7 +1665,7 @@ fdcretry(fdc)
int error = EIO;
fd = TAILQ_FIRST(&fdc->sc_drives);
- bp = fd->sc_q.b_actf;
+ bp = fd->sc_bp;
fdc->sc_overruns = 0;
if (fd->sc_opts & FDOPT_NORETRY)
