|
osdir.com mailing list archive |
|
Subject: Re: [PATCH] serial: remove "too much work for irq" printk - msg#00014List: linux.serialThis is going to put trouble in other places unless, at least, it can be turned off. The UART serial interface is heavily emulated as a console interface without an actual serial port behind it, both in hardware and software. Rates will typically vastly exceed real serial port rates, Yes Dell do it, HP do it, IBM do it. Have done for years, never caused us a problem. Its only KVM tripping it. As to bit rate we support up to about 1 to 1.5 Mbit. FWIW, the highest rate I've seen in hardware is a FIFO about 4K deep that can be polled at about 25 MHz when all the overhead is accounted for. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ Thread at a glance:
Previous Message by Date: click to view message previewRe: [PATCH] serial: remove "too much work for irq" printk> This is going to put trouble in other places unless, at least, it can be > turned off. The UART serial interface is heavily emulated as a console > interface without an actual serial port behind it, both in hardware and > software. Rates will typically vastly exceed real serial port rates, Yes Dell do it, HP do it, IBM do it. Have done for years, never caused us a problem. Its only KVM tripping it. As to bit rate we support up to about 1 to 1.5 Mbit. Alan - To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Next Message by Date: click to view message previewRe: [PATCH] serial: remove "too much work for irq" printkOn Sat 2008-01-12 21:24:57, Alan Cox wrote: > On Sat, 12 Jan 2008 15:15:43 -0500 > Benjamin LaHaise <bcrl@xxxxxxxxx> wrote: > > > When using kvm with a serial console, the serial driver will print out > > "too much work for irq4" on any heavy activity (ie vi on a file repainting > > the terminal). This message is entirely spurious, as output continues to > > work fine. Remove the message as it corrupts screen output and is far too > > easy to trigger. > > NAK. This is a qemu/kvm emulation bug. The real check is there to catched > jammed IRQs and combined with the IRQ bug handling nowdays does actually > do the intended job. > > Our serial port code (correctly) interprets a continuous stream of bytes > at an impossible bit rate as an error. KVM should be emulating to some > extent at least the timing on serial interfaces or using a virtualised > interface. How can you tell apart impossible bit rate from really slow CPU, or maybe just an SMI storm, or heavy busmaster DMA? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Previous Message by Thread: click to view message previewRe: [PATCH] serial: remove "too much work for irq" printk> This is going to put trouble in other places unless, at least, it can be > turned off. The UART serial interface is heavily emulated as a console > interface without an actual serial port behind it, both in hardware and > software. Rates will typically vastly exceed real serial port rates, Yes Dell do it, HP do it, IBM do it. Have done for years, never caused us a problem. Its only KVM tripping it. As to bit rate we support up to about 1 to 1.5 Mbit. Alan - To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Next Message by Thread: click to view message previewRe: [PATCH] serial: remove "too much work for irq" printkOn Sat 2008-01-12 21:24:57, Alan Cox wrote: > On Sat, 12 Jan 2008 15:15:43 -0500 > Benjamin LaHaise <bcrl@xxxxxxxxx> wrote: > > > When using kvm with a serial console, the serial driver will print out > > "too much work for irq4" on any heavy activity (ie vi on a file repainting > > the terminal). This message is entirely spurious, as output continues to > > work fine. Remove the message as it corrupts screen output and is far too > > easy to trigger. > > NAK. This is a qemu/kvm emulation bug. The real check is there to catched > jammed IRQs and combined with the IRQ bug handling nowdays does actually > do the intended job. > > Our serial port code (correctly) interprets a continuous stream of bytes > at an impossible bit rate as an error. KVM should be emulating to some > extent at least the timing on serial interfaces or using a virtualised > interface. How can you tell apart impossible bit rate from really slow CPU, or maybe just an SMI storm, or heavy busmaster DMA? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Loading Comments...
|
|
