DWC OTG TX path optimisation for 11-current
Svatopluk Kraus
onwahe at gmail.com
Fri Jul 31 11:55:04 UTC 2015
On Fri, Jul 31, 2015 at 11:15 AM, Hans Petter Selasky <hps at selasky.org> wrote:
> Hi,
>
> I did some testing myself and I see the polling handler can loop many times
> when USB is active. Instead of 2 as a polling limit I've set 16. Hope this
> works too. Works fine over here.
>
> https://svnweb.freebsd.org/changeset/base/286118
>
Definitely, some limitation was needed there. Thanks.
Unfortunatelly, it turned out that it does not help with my problem.
It has affected system response time in good way for some time after
the trigger is pulled. However, after 17 hours when buildworld
finished, system response time is bad again.
It also turns out that I have a problem with booting my kernels. So I
cannot test the extra "clear RX FIFO level interrupt" patch as even
this one line of code causes that kernel does not boot. It freezes at
very beginning and even first printf is not printed. Thus I have to
debug this problem firstly. It will be very funny without either jtag
or early printf. ;)
Meantime, I have noticed that after reboot (system is 99% idle), I'm
getting the following output from vmstat:
root at rpi2:~ # vmstat -i -w 1
interrupt total rate
irq1: mbox0 27 0
irq2: vchiq0 6 0
irq17: bcm283x_dwco 2266826 20654
irq26: bcm_dma0 962 9
irq65: uart0 21516 196
irq70: sdhci_bcm0 556 5
irq73: generic_time 25952 236
irq76: ipi 23182 211
Total 2339027 21312
irq1: mbox0 0 0
irq2: vchiq0 0 0
irq17: bcm283x_dwco 25734 23983
irq26: bcm_dma0 0 0
irq65: uart0 527 491
irq70: sdhci_bcm0 0 0
irq73: generic_time 245 228
irq76: ipi 99 92
Total 26605 24795
irq1: mbox0 0 0
irq2: vchiq0 0 0
irq17: bcm283x_dwco 25679 24022
irq26: bcm_dma0 0 0
irq65: uart0 476 445
irq70: sdhci_bcm0 0 0
irq73: generic_time 246 230
irq76: ipi 100 94
Total 26501 24790
irq1: mbox0 0 0
irq2: vchiq0 0 0
irq17: bcm283x_dwco 25683 24025
irq26: bcm_dma0 0 0
irq65: uart0 476 445
irq70: sdhci_bcm0 0 0
irq73: generic_time 245 229
irq76: ipi 104 97
Total 26508 24797
IMO, 24000 interrupts per a second for bcm283x_dwco is too many.
Svata
> --HPS
>
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