On Mon, Jun 24, 2024 at 01:45:17PM -0700, Doug Anderson wrote: > Also: if we're looking at quick/easy to land and just fix the hard > lockup, I'd vote for this (I can send a real patch, though I'm about > to go on vacation): > > -- > > @@ -904,8 +904,8 @@ static void qcom_geni_serial_handle_tx_fifo(struct > uart_port *uport, > goto out_write_wakeup; > > if (!port->tx_remaining) { > - qcom_geni_serial_setup_tx(uport, pending); > - port->tx_remaining = pending; > + port->tx_remaining = min(avail, pending); > + qcom_geni_serial_setup_tx(uport, port->tx_remaining); > > irq_en = readl(uport->membase + SE_GENI_M_IRQ_EN); > if (!(irq_en & M_TX_FIFO_WATERMARK_EN)) > > -- > > That will fix the hard lockup, is short and sweet, and also doesn't > end up outputting NUL bytes. Yeah, this might be a good stop gap even if performance suffers. > I measured time with that. I've been testing with a file I created > called "alphabet.txt" that just contains the letters A-Z repeated 3 > times followed by a "\n", over and over again. I think gmail will kill > me with word wrapping, but basically: > head -200 /var/alphabet.txt | wc > 200 200 15800 > > Before my patch I ran `time head -200 /var/alphabet.txt` and I got: > > real 0m1.386s > > After my patch I ran the same thing and got: > > real 0m1.409s > > So it's slower, but that's not 25% slower. I get 1.7% slower: > > In [6]: (1.409 - 1.386) / 1.386 * 100 > Out[6]: 1.659451659451669 > > IMO that seems like a fine slowdown in order to avoid printing NUL bytes. With my 500K dmesg file test I see a similar performance drop as with your full series even if seems to behave slightly better (e.g. 20% drop instead of 24%). Johan