On Wed, Jun 20, 2018 at 12:32:14AM +0200, Thomas Gleixner wrote: > On Tue, 19 Jun 2018, Fenghua Yu wrote: > > > On Tue, Jun 19, 2018 at 10:57:44AM +0200, Thomas Gleixner wrote: > > > On Fri, 15 Jun 2018, Fenghua Yu wrote: > > > > > > > MOVDIRI moves doubleword or quadword from register to memory through > > > > direct store which is implemented by using write combining (WC) for > > > > writing data directly into memory without caching the data. > > > > > > And that is useful for what? > > > > Programmable agents can handle streaming offload (e.g. high speed packet > > processing in network). Hardware implements a doorbell (tail pointer) > > register that is updated by software when adding new work-elements to > > the streaming offload work-queue. > > > > MOVDIRI can be used as the doorbell write which is a 4-byte or 8-byte > > uncachable write to MMIO. MOVDIRI has lower overhead than other ways > > to write the doorbell. > > > > In low latency offload (e.g. Non-Volatile Memory, etc), MOVDIR64B writes > > work descriptors (and data in some cases) to device-hosted work-queues > > with atomicity. > > Makes sense, but why is this not part of the changelog ?
Sorry. I forgot to put the usage info in the commit description. I will add it in the next version. > > Thanks, > > tglx Thanks. -Fenghua
