On 09/04/2013 01:48 PM, Pekka Enberg wrote:
On Wed, Sep 4, 2013 at 8:40 PM, Jonathan Austin <jonathan.austin@xxxxxxx> wrote:'top' works on ARM with virtio console. I've just done some new testing and with the serial console emulation and I see the same as you're reporting. Previously with the 8250 emulation I'd booted to a prompt but didn't actually test top... I'm looking in to fixing this now... Looks like I need to find the right place from which to call serial8250_flush_tx now that it isn't getting called every tick. I've done the following and it works fixes 'top' with serial8250: -------8<---------- diff --git a/tools/kvm/hw/serial.c b/tools/kvm/hw/serial.c index 931067f..a71e68d 100644 --- a/tools/kvm/hw/serial.c +++ b/tools/kvm/hw/serial.c @@ -260,6 +260,7 @@ static bool serial8250_out(struct ioport *ioport, struct kvm *kvm, u16 port, dev->lsr &= ~UART_LSR_TEMT; if (dev->txcnt == FIFO_LEN / 2) dev->lsr &= ~UART_LSR_THRE; + serial8250_flush_tx(kvm, dev); } else { /* Should never happpen */ dev->lsr &= ~(UART_LSR_TEMT | UART_LSR_THRE); ------------->8----------- I guess it's a shame that we'll be printing each character (admittedly the rate will always be relatively low...) rather than flushing the buffer in a batch. Without a timer, though, I'm not sure I see a better option - every N chars doesn't seem like a good one to me. If you think that looks about right then I'll fold that in to the patch series, probably also removing the call to serial8250_flush_tx() in serial8250__receive.Yeah, looks good to me and makes top work again.
We might want to make sure performance isn't hit with stuff that's intensive on the serial console. Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
