[illumos-Developer] Code Review: WRITE_SAME support for COMSTAR's stmf_sbd

[Dan McDonald]

On Wed, May 18, 2011 at 10:22:03AM -0700, Richard Elling wrote:
> I'd like to see a dtrace probe around the actual I/O, sbd_scsi.c line 2307
> so we can measure how long the actual write same I/O takes.

Hmmm... you could measure this with judicious FBT, I would imagine:

===================== (Cut up to and including here.) =====================

sbd_write_same_data:entry
{
        self->trace = 1;
        self->time = 0;
}

sbd_data_write:entry
/self->trace == 1/
{
        self->curtime = timestamp;
}

sbd_data_write:return
/self->trace == 1/
{
        self->time += (timestamp - self->curtime);
}

sbd_write_same_data:return
{
        self->trace = 0;
        printf("I/O time in one call is %d", self->time);
}

===================== (Cut up to and including here.) =====================

But if you've a more precise probe semantic in mind, I'm game.  Please expand
a little so I know what you're shooting for.

Thanks,
Dan