On 06/01, Adrian Hunter wrote: > On 31/05/22 23:10, 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 > > Wouldn't it depend on how much data might be in the cache? I've got this average latency from 100 commands of write+cache_flush vs. write(FUA). I think the cached data should be the same as this chunk size. > Do you have real-world use-cases where the difference is measurable? I'm approaching this based on 1) f2fs uses FUA for checkpoint and fsync, and 2) iomap uses FUA for O_DIRECT|O_DSYNC case [1]. [1] https://lore.kernel.org/lkml/20220527205955.3251982-1-jaegeuk@xxxxxxxxxx/ > > > > > 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, > > Wouldn't it be more appropriate to make it a UFS_DEVICE_QUIRK_ > since it presumably depends on the UFS device not the host controller? > > Also, as already commented by others, there needs to be a user of > the quirk Since I asked SoC vendors can verify the performance with this quirk, I need to wait for their reply. Meanwhile, I'm willing to disable FUA in Pixel devices, which I cannot post any patch directly to LKML. Agreed that, if there's no other user in upstream, I'm okay to drop this. > > > }; > > > > enum ufshcd_caps {
