Hello, >> >>I have found out that when linking a userspace application with -lpthread, >>then for some reason, a device driver's read() routine suddenly has >>IO_NDELAY set in flags. Bug? > >No. This is as it should be, because -lpthread does threads in *one* >kernel process, so it has to intercept blocking operations so it can >switch to another thread instead, or call select/poll/kevent if needed, >so not all threads hang if *one* executes a blocking operation. > How could I help the high CPU usage then? The device driver read routine always prematurely exits because IO_NDELAY is set (and there's nothing to read - so EWOULDBLOCK is returned).
Jan Engelhardt --
