On Thu, 17 Oct 2019 07:27:34 +0000 Shahaf Shuler <shah...@mellanox.com> wrote:
> Some PMDs inline the mbuf data buffer directly to device. This is in > order to save the overhead of the PCI headers involved when the device > DMA read the buffer pointer. For some devices it is essential in order > to reach the pick BW. > > However, there are cases where such inlining is in-efficient. For example > when the data buffer resides on other device memory (like GPU or storage > device). attempt to inline such buffer will result in high PCI overhead > for reading and copying the data from the remote device. > > To support a mixed traffic pattern (some buffers from local DRAM, some > buffers from other devices) with high BW, a hint flag is introduced in > the mbuf. > Application will hint the PMD whether or not it should try to inline the > given mbuf data buffer. PMD should do best effort to act upon this > request. > > Signed-off-by: Shahaf Shuler <shah...@mellanox.com> This kind of optimization is hard, and pushing the problem to the application to decide seems like the wrong step. Can the driver just infer this already because some mbuf's are external?
