On Thu, Apr 09, 2020 at 03:25:32PM +0900, SAITOH Masanobu wrote: > On 2020/04/09 11:08, David Young wrote: > > On Wed, Apr 08, 2020 at 11:01:52PM +0000, Jaromir Dolecek wrote: > > > on I219 I observe about 35% transmit performance drop when tso4 enabled > > > > This sounds familiar. There was a bug affecting TCP segmentation > > offload (I think) that we found at CoyotePoint. ISTR > > bus_dmamap_load_mbuf(9) failed with EFBIG because under some > > circumstances the number of segments in the DMA map was too small > > for the mbuf chain. The driver would drop the whole mbuf chain > > on the floor. This showed up as terrible performance under some > > circumstances---possibly when the TCP window grew long? The solution > > was to increase the number of DMA segments, *I think*. > > m_defrag() was added to -current in September 2018, and 9.0, > 8.1, post 7.2 have this code.
Thank you, that's just the change I was thinking of. Dave -- David Young dyo...@pobox.com Urbana, IL (217) 721-9981