On Thu, Jan 03, 2019 at 11:57:38PM -0500, Martin K. Petersen wrote: > > Ewan, > > > SBC-5 says that support for the grouping function is indicated by the > > GROUP_SUP bit in the Extended Inquiry VPD page (86h). I'm not sure > > how many devices actually support that page though. Probably most > > don't. > > Several devices support it, albeit for various different purposes. It's > one of these wonderful features whose interpretation was left outside > the scope of the spec for a long time. > > So even though we absolutely and positively need to make setting GROUP > NUMBER conditional on GROUP_SUP being reported, we also need additional > information from the storage about how the field should be interpreted. > > The official way to report hinting is for the device to implement the IO > Advice Hints Grouping mode page. I wrote some code to support that but > no vendors that I know of ended up actually shipping an implementation. > A few implemented my older I/O class proposal but didn't ship that > either despite really convincing performance results. > > If Randall has access to a device which implements hinting, I'd love to > know more. I am working on Android phone. The idea is to enable write hint for Turbo write UFS feature. Turbo write feature in UFS 3.x is under discussion in JEDEC JC-64. This patch is the under-lying framework for supporting this feature. > > -- > Martin K. Petersen Oracle Linux Engineering
