Hi Marc, On Tue. 9 Mar 2021 at 19:27, Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> wrote: > > On 3/8/21 5:34 PM, Vincent Mailhol wrote: > > This driver supports the ES581.4, ES582.1 and ES584.1 interfaces from > > ETAS GmbH (https://www.etas.com/en/products/es58x.php). > > > > Co-developed-by: Arunachalam Santhanam <arunachalam.santhanam@xxxxxxxxxxxx> > > Signed-off-by: Arunachalam Santhanam <arunachalam.santhanam@xxxxxxxxxxxx> > > Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> > > I'm not sure if you're supposed to change dql.min_limit from the driver. One thing for sure, I am the only one to do it. The reason to do so is because benchmarks show me that values below this threshold are not good for this device (and I try to be very permissive on the values). USB introduces a lot of latency and the small PDU of CAN does not help. The BQL is here to remediate, however, the algorithms can take time to adjust, especially if there are small bursts. Modifying the dql.min_limit was the only solution I found to make sure that packets can be sent in bulk even during small burst events. The BQL was not designed for USB nor was it designed for CAN which probably explains why I am the first one to ever have thought of using dql.min_limit like this. Using dql.min_limit is a hack and I pledge guilty for it. However, because this hack brings performance improvement, I would like to keep it if you do not mind. Yours sincerely, Vincent
