Messages in this thread | | | Date | Tue, 6 Jan 2009 19:46:54 +0000 (GMT) | From | Hugh Dickins <> | Subject | Re: [PATCH] block: export SSD/non-rotational queue flag through sysfs |
| |
On Mon, 5 Jan 2009, Sitsofe Wheeler wrote: > Kay Sievers wrote: > > On Mon, Jan 5, 2009 at 19:54, Jens Axboe <jens.axboe@oracle.com> wrote: > > > On Mon, Jan 05 2009, Bartlomiej Zolnierkiewicz wrote: > > > > > > +static struct queue_sysfs_entry queue_nonrot_entry = { > > > > + .attr = {.name = "nonrot", .mode = S_IRUGO | S_IWUSR }, > > > > + .show = queue_nonrot_show, > > > > + .store = queue_nonrot_store, > > > > +}; > > > > + > > > Lets please use a better name for export reasons, non-rotational is a > > > lot better. Nobody will know what nonrot means :-) > > > > What's that negation good for? Can't we just have "rotational", like > > we have "removable" and not "non-removable"? :) > > How about cheapseek? fastrandom? flash? ssd? However the internal flag is > called QUEUE_FLAG_NONROT so it kind of makes sense just to leave it as > nonrot...
Many thanks to Bart (and Alan) for this patch: just what I'd been hoping for when I wrote (25 Nov) But how to get my SD card, accessed by USB card reader, reported as NONROT?
However, may I join Kai in protesting the negative boolean flag? I've never quite recovered from CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER; and while this is obviously nowhere near the same league, I'd much rather stay well away.
I don't like the "nonrot" or "rotational" at all myself: though you may be able to advance convincing arguments why it's not accidental, isn't the rotationality pretty much incidental to whether the seeks are cheap? I imagine a long bar loaded with data, which zips back and forth through the reader: nothing rotational, but expensive seeks. (I had been going to propose magnetic tape, but the rotation of the spools muddies that argument.)
When doing the swap patch, though I toed the line with SWP_NONROT for quite a while (I do dislike using different names for the same notion at different levels), I couldn't stomach it in the end, and went for SWP_SOLIDSTATE.
But I particularly like Sitsofe's "cheapseek". Is that is an accurate representation of how the I/O schedulers treat it? then please can we name the user-visible sysfs file accordingly?
The kernel-internal name is much less important, though I'd be pretty happy to have CHEAPSEEK instead of NONROT throughout there too.
Oh, another problem with NONROT: flash rots a lot sooner than disk, doesn't it?
Hugh
| |