On Thu, 2021-10-28 at 13:21 -0700, Bart Van Assche wrote: [...] > Hi James, > > The help with trying to find a solution is appreciated. > > One of the software developers who is familiar with HPB explained to > me that READ BUFFER and WRITE BUFFER commands may be received in an > arbitrary order by UFS devices. The UFS HPB spec requires UFS devices > to be able to stash up to 128 such pairs. I'm concerned that leaving > out WRITE BUFFER commands only will break the HPB protocol in a > subtle way. Based on the publicly available information (the hotstorage paper) I don't belive it can. The Samsung guys also appear to confirm that the use of WRITE BUFFER is simply an optimzation for large requests: https://lore.kernel.org/all/20211025051654epcms2p36b259d237eb2b8b885210148118c5d3f@epcms2p3/ As did the excerpt from the spec you posted. It will cause slowdowns for reads of > 32kb, because they have to go through the native FTL lookup now, but there shouldn't be any functional change. Unless there's anything else in the proprietary spec that contradicts this? James
