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The rtt-upiu packets precede any data-out upiu packets, thus synchronizing the data input to the device: this mostly applies to write operations, but there are other operations that requires rtt as well. There are several rules binding this rtt - data-out dialog, specifically There can be at most outstanding bMaxNumOfRTT such packets. This might have an effect on write performance (sequential write in particular), as each data-out upiu must wait for its rtt sibling. UFSHCI expects bMaxNumOfRTT to be min(bDeviceRTTCap, NORTT). However, as of today, there does not appears to be no-one who sets it: not the host controller nor the driver. It wasn't an issue up to now: bMaxNumOfRTT is set to 2 after manufacturing, and wasn't limiting the write performance. UFS4.0, and specifically gear 5 changes this, and requires the device to be more attentive. This doesn't come free - the device has to allocate more resources to that end, but the sequential write performance improvement is significant. Early measurements shows 25% gain when moving from rtt 2 to 9. Therefore, set bMaxNumOfRTT to be min(bDeviceRTTCap, NORTT) as UFSHCI expects. Signed-off-by: Avri Altman <avri.altman@wdc.com> Link: https://lore.kernel.org/r/20240530142510.734-2-avri.altman@wdc.com Reviewed-by: Bean Huo <beanhuo@micron.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> |
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| .. | ||
| ufs_quirks.h | ||
| ufs.h | ||
| ufshcd.h | ||
| ufshci.h | ||
| unipro.h | ||