On Sun, 4 Jan 2009 10:16:57 -0800 (PST) Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > On Sun, 4 Jan 2009, Arjan van de Ven wrote: > > > > To see this working, I uploaded a "before" and "after" kernel > > bootchart for one of my testboxes at > > > > http://www.fenrus.org/linux/before.svg > > http://www.fenrus.org/linux/after.svg > > Ok, so why does the serial port init take so long? That's a quarter > of a second for you, which is ridiculous. good question; I was about to start looking into that one (but wanted to get the patches out first before I did more than 3 to not waste time on some dead-end approach if it ends up being that) > > I _think_ it's the irq auto-probing, but that's just a guess. I kinda was hoping that in part it was a scaling thing with the number of ports (4 in my .config) so that I could do the ports asynchronous compared to eachother ;-) > The irq auto-probing itself also has a few excessive delays, like > waiting for 0.1 s just to wait for spurious interrupts to trigger. > Doing the extra unnecessary probe makes that doubly expensive. > > Does this patch make any difference to you? I'm not at all sure that > it's the irq probing, but if it is, then this should make the serial > probe go much faster. it turned it into a 25 msec deal .. pretty good improvement in my book. (now I still might want to try to do this async so that it becomes 25/4 ... but the pressure i -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
