Hi DS, First of all, thank you for your willingness to test this stuff!
> On Linux 4.19.0-6-amd64 (Debian stable), the problem with the 10ms > select seems to be not present. With or without the ASYNC_LOW_LATENCY > patch, the time to dump a flash is the same, eg. 3m45s for the FCDEV3B > using the pldkit FT2232D at 812500 baud. Dumping the flash is not the right operation to test for the issue at hand. When you execute a loadtool command like dump2bin or flash dump2bin, loadtool sends a single DUMP command to loadagent, and loadagent then emits the entire dump (up to 8 MiB) in one fell swoop without needing further commands from loadtool. Thus the time it takes to perform a dump will always be equal to the time it takes loadagent to emit the full volume of data out through Calypso's UART transmitter, regardless of how the Linux kernel on the host side subsequently passes these characters to loadtool, in big or small chunks. Instead the problem which Serg L reported in 2019-07 and which I may have also seen myself when I tried to run newer Linux-4.4.y versions (which also had the much bigger problem of causing kernel panics under non-understood conditions, hence I gave up on them) manifests on operations like fc-xram loading or flash programming. When you program device flash with fc-loadtool (as opposed to dumping it), loadtool sends one line at a time to loadagent (256 bytes at a time in the case of flash program-bin or one S-record at a time in the case of program-m0), then collects the echo from the target and waits for the loadagent command to complete before sending the next line. fc-xram similarly sends each S-record as a separate loadagent command, collecting the echo and waiting for completion after each line. For these operations, if the Linux kernel inserts a delay on select returning when serial input is ready, the resulting operation time will be significantly extended. I would greatly appreciate it if you could test flash programming or fc-xram loading on your system and see if the ASYNC_LOW_LATENCY change makes any improvement. I am otherwise ready to put out the new FC host tools release, just waiting for these tests. Hasta la Victoria, Siempre, Mychaela aka The Mother _______________________________________________ Community mailing list Community@freecalypso.org https://www.freecalypso.org/mailman/listinfo/community