On Mon, 21 May 2018 14:04:57 -0700, Saeed Mahameed wrote: > From: Huy Nguyen <h...@mellanox.com> > > In this patch, we add dcbnl buffer attribute to allow user > change the NIC's buffer configuration such as priority > to buffer mapping and buffer size of individual buffer. > > This attribute combined with pfc attribute allows advance user to > fine tune the qos setting for specific priority queue. For example, > user can give dedicated buffer for one or more prirorities or user > can give large buffer to certain priorities. > > We present an use case scenario where dcbnl buffer attribute configured > by advance user helps reduce the latency of messages of different sizes. > > Scenarios description: > On ConnectX-5, we run latency sensitive traffic with > small/medium message sizes ranging from 64B to 256KB and bandwidth sensitive > traffic with large messages sizes 512KB and 1MB. We group small, medium, > and large message sizes to their own pfc enables priorities as follow. > Priorities 1 & 2 (64B, 256B and 1KB) > Priorities 3 & 4 (4KB, 8KB, 16KB, 64KB, 128KB and 256KB) > Priorities 5 & 6 (512KB and 1MB) > > By default, ConnectX-5 maps all pfc enabled priorities to a single > lossless fixed buffer size of 50% of total available buffer space. The > other 50% is assigned to lossy buffer. Using dcbnl buffer attribute, > we create three equal size lossless buffers. Each buffer has 25% of total > available buffer space. Thus, the lossy buffer size reduces to 25%. Priority > to lossless buffer mappings are set as follow. > Priorities 1 & 2 on lossless buffer #1 > Priorities 3 & 4 on lossless buffer #2 > Priorities 5 & 6 on lossless buffer #3 > > We observe improvements in latency for small and medium message sizes > as follows. Please note that the large message sizes bandwidth performance is > reduced but the total bandwidth remains the same. > 256B message size (42 % latency reduction) > 4K message size (21% latency reduction) > 64K message size (16% latency reduction) > > Signed-off-by: Huy Nguyen <h...@mellanox.com> > Signed-off-by: Saeed Mahameed <sae...@mellanox.com>
On a cursory look this bares a lot of resemblance to devlink shared buffer configuration ABI. Did you look into using that? Just to be clear devlink shared buffer ABIs don't require representors and "switchdev mode".
