On Thu, Jul 21, 2022 at 02:08:33PM +0800, Weitao Wang wrote: > Usb core introduce the mechanism of giveback of URB in tasklet context to > reduce hardware interrupt handling time. On some test situation(such as > FIO with 4KB block size), when tasklet callback function called to > giveback URB, interrupt handler add URB node to the bh->head list also. > If check bh->head list again after finish all URB giveback of local_list, > then it may introduce a "dynamic balance" between giveback URB and add URB > to bh->head list. This tasklet callback function may not exit for a long > time, which will cause other tasklet function calls to be delayed. Some > real-time applications(such as KB and Mouse) will see noticeable lag. > > Fix this issue by taking new URBs giveback in next tasklet function call. The patch also replaces the local high_prio_bh variable with a new bh->high_prio structure member. This should be mentioned in the patch description. Alan Stern
