On Thu, Oct 7, 2010 at 8:30 PM, wu zhangjin <[email protected]> wrote: > Hi, Jack > > On 10/7/10, Jack Daniel <[email protected]> wrote: >> Hi Wu, >> >> I was going through your latency tracing implementation for loongson. >> Could you please assist me in understanding the following. >> >> 1) How is the latency tracing implemented here different from ftrace >> tracer function "irqsoff" ? "irqsoff" calculates the time when >> interrupts are disabled. > > What do you mean "the latency tracing implemented here"? In reality, > the latency tracers I have used are the ones you said above: irqsoff > tracer, preemptoff tracer and preemptirqsoff tracer, wakeup tracer ...
My apologies for not articulating my question properly. What I meant was the latency tracing support available at Device Drivers ---> [*] PREEMPT_RT Specific Device Drivers ---> <*> Interrupt Latency Driver I see that you are the only one to support this in your tree for loongson. How different is this from "irqsoff" supported by Ftrace? > > But at the time I was using them, they didn't work well for they could > not provide high resolution timestamp: The unit of the timestamp > resolution is only ms, so, the latency result is always >= 1000 us, > which can not reflect the real situation of the latencies. Therefore, > I have tried to fix it via adding the high resolution sched_clock() > support. > >> >> 2) Could you give me a reference or guide on how to implement the same >> for another mips platform such as Octeon? > > Which kernel version are you using? For the latest kernel versions, > the latency tracers should be supported very well except the high > resolution sched_clock(). For Octeon, the support of high resolution > sched_clock() has already been there from 2.6.33, but for the r4k > MIPS, you may need to apply the patches from the patchwork of > linux-mips: > > http://patchwork.linux-mips.org/patch/1102/ > http://patchwork.linux-mips.org/patch/1104/ Thank you for this tip, I will take a look. Regards, Jack. -- You received this message because you are subscribed to the Google Groups "loongson-dev" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/loongson-dev?hl=en.
