On 05/31, Eric Biggers wrote:
> On Tue, May 31, 2022 at 01:10:53PM -0700, Jaegeuk Kim wrote:
> > UFS stack shows very low performance of FUA comparing to write and cache_flush.
> > Let's add a quirk to adjust it.
> >
> > E.g., average latency according to the chunk size of write
> >
> > Write(us/KB) 4 64 256 1024 2048
> > FUA 873.792 754.604 995.624 1011.67 1067.99
> > CACHE_FLUSH 824.703 712.98 800.307 1019.5 1037.37
> >
> > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> > ---
> > drivers/scsi/ufs/ufshcd.c | 3 +++
> > drivers/scsi/ufs/ufshcd.h | 5 +++++
> > 2 files changed, 8 insertions(+)
> >
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index 3f9caafa91bf..811f3467879c 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -5035,6 +5035,9 @@ static int ufshcd_slave_configure(struct scsi_device *sdev)
> > */
> > sdev->silence_suspend = 1;
> >
> > + if (hba->quirks & UFSHCD_QUIRK_BROKEN_FUA)
> > + sdev->broken_fua = 1;
> > +
> > ufshcd_crypto_register(hba, q);
> >
> > return 0;
> > diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> > index 94f545be183a..6c480c6741d6 100644
> > --- a/drivers/scsi/ufs/ufshcd.h
> > +++ b/drivers/scsi/ufs/ufshcd.h
> > @@ -602,6 +602,11 @@ enum ufshcd_quirks {
> > * support physical host configuration.
> > */
> > UFSHCD_QUIRK_SKIP_PH_CONFIGURATION = 1 << 16,
> > +
> > + /*
> > + * This quirk disables FUA support.
> > + */
> > + UFSHCD_QUIRK_BROKEN_FUA = 1 << 17,
> > };
>
> "Broken" is ambiguous. IIUC, the issue is that FUA performance is very bad, not
> that it doesn't work. Can you clarify the intent in the comment?
My intent is FUA was supposed to be better than write+cache_flush.
>
> Also, this patch does nothing by itself. Which UFS host driver(s) need this
> quirk bit? Can you update them to use it? Or do they all need this, in which
> case a quirk bit would be unnecessary?
Likewise other quick bits, using this is up to SoC or UFS vendors. I
think that combination is up to OEMs who is building the product.
>
> - Eric
