Re: question about UARTs support code in the kernel

#1 (**permalink**) 02-18-2008, 07:12 AM

Michael Shalayeff wrote:

>Making, drinking tea and reading an opus magnum from Alexei G. Malinin:
>
>
>>Hello.
>>
>>Can anybody tell me what is the idea of setting
>>TX trigger to maximum? In this case we have
>>no performance gain during servicing TX
>>interrupts because, for example, when TX fifo
>>is 64 bytes and TX trigger is 56 bytes and TX fifo
>>is full - TX interrupt is activated after TX fifo
>>transmits every 8 bytes if traffic is high.
>>I think that setting TX trigger to minimum can
>>give us performance gain because TX interrupt
>>will be activated less frequently then in the
>>above example and the kernel will have more time
>>to service other tasks.
>>
>>
>
>8 chars at 115200 be about 1000 ints/sec -- not a problem.
>the problem at hands is to make sure there is always smth
>in the tx buffer while interrupt is being serviced thus
>avoiding stalls due to delys for the intr handler to
>push new data into the tx buffer.
>
>cu
>
>
>
ok but setting TX trigger to reasonably low value, e. x. 4 or 8 bytes,
solves this problem but with a performance gain?!

--
Alexei Malinin,
Specialist of
Information Technologies Department,
Basic Element Company, Moscow

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode