Am 2015-04-27 um 16:36 schrieb Luke Gorrie: > On 27 April 2015 at 16:30, Jan Kiszka <jan.kiszka@xxxxxxxxxxx> wrote: > >> Today, we have posted interrupts to avoid the vm-exit on the target CPU, >> but there is nothing yet (to my best knowledge) to avoid the exit on the >> sender side (unless we ignore security). That's the same problem with >> intra-guest IPIs, BTW. >> >> For throughput and given NAPI patterns, that's probably not an issue as >> you noted. It may be for latency, though, when almost every cycle counts. >> > > Poll-mode networking applications (DPDK, Snabb Switch, etc) are typically > busy-looping to poll the vring. They may have a very short usleep() between > checks to save power but they don't wait on their eventfd. So for those > particular applications latency is on the order of tens of microseconds > even without guest exits. That's one side, don't forget the others (the "normal" guests). Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
