Messages in this thread Patch in this message | | | Date | Wed, 8 Nov 2023 12:21:16 -0500 | From | Steven Rostedt <> | Subject | Re: [RFC PATCH 82/86] treewide: mtd: remove cond_resched() |
| |
On Wed, 8 Nov 2023 16:32:36 +0000 Matthew Wilcox <willy@infradead.org> wrote:
> On Wed, Nov 08, 2023 at 05:28:27PM +0100, Miquel Raynal wrote: > > > --- a/drivers/mtd/nand/raw/nand_legacy.c > > > +++ b/drivers/mtd/nand/raw/nand_legacy.c > > > @@ -203,7 +203,13 @@ void nand_wait_ready(struct nand_chip *chip) > > > do { > > > if (chip->legacy.dev_ready(chip)) > > > return; > > > - cond_resched(); > > > + /* > > > + * Use a cond_resched_stall() to avoid spinning in > > > + * a tight loop. > > > + * Though, given that the timeout is in milliseconds, > > > + * maybe this should timeout or event wait? > > > > Event waiting is precisely what we do here, with the hardware access > > which are available in this case. So I believe this part of the comment > > (in general) is not relevant. Now regarding the timeout I believe it is > > closer to the second than the millisecond, so timeout-ing is not > > relevant either in most cases (talking about mtd/ in general). > > I think you've misunderstood what Ankur wrote here. What you're > currently doing is spinning in a very tight loop. The comment is > suggesting you might want to msleep(1) or something to avoid burning CPU > cycles. It'd be even better if the hardware could signal you somehow, > but I bet it can't. >
Oh how I wish we could bring back the old PREEMPT_RT cpu_chill()...
#define cpu_chill() msleep(1)
;-)
-- Steve
> > > + */ > > > + cond_resched_stall(); > > > } while (time_before(jiffies, timeo)); > > Thanks, > > Miquèl > >
| |