Messages in this thread | | | Date | Mon, 23 Nov 2009 13:34:23 +0000 | From | Alan Cox <> | Subject | Re: [bisected] pty performance problem |
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> > So you'd prefer to detect devices that are byte based or message based > > by what method ? > > I'd not delay the worklet by default - i.e. i'd do Mike's patch.
Certainly stuff like pty should not delay > > Havent tested all effects of it though - do you have any estimation > about negative effects from such a change? We do have hard numbers > (latencies in the millisecs range) from the opposite direction and those > numbers arent pretty.
On a PC I'm not too worried - we might burn a bit more CPU and Arjan might even manage to measure it somewhere. There is the theoretical bad case where we end up at 100% CPU because the irq, wake, process one char, irq wake, process one char sequence fits the CPU so we don't sleep.
Embedded might be more of a concern, the old behaviour comes from 386/486 days with low CPU power.
USB doesn't worry me - USB devices generally have their own buffering algorithm and use a timer so that they batch data efficiently into USB buffers.
The drivers/serial layer is often run with low latency set anyway so that seems to be ok for the most part.
Give it a go, send the patch to the maintainer, try it in -next and see if anyone screams.
Alan
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