Hi all,
On 7/25/07, Juerg Haefliger <juergh at gmail.com> wrote:
> Hi Eric,
>
>
> > I was very happy to see dme1737 support added, thank you! Now I can get
> > all the info out of my compaq sr1710nx cheapo server. :)
>
> Glad you like it :-) I can finally tell my wife that the time I spent
> on the driver wasn't all wasted...
>
>
> > It all works - I did notice, though, that when I run "sensors" it's very
> > slow to read the sysfs file:
> >
> > write(1, "Adapter: SMBus PIIX4 adapter at "..., 37) = 37 <0.000055>
> > open("/sys/class/i2c-adapter/i2c-0/0-002e/in0_input", O_RDONLY) = 3
> > <0.000032>
> > fstat(3, {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0 <0.000009>
> > mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
> > = 0x2b7f69d6b000 <0.000014>
> > read(3, "0\n", 4096) = 2 <1.535188>
> >
> > 1.53 seconds to read "0\n" ! :)
> >
> > Any idea if this is a hardware or software delay? I haven't yet dug
> > into profiling the kernel code to see what might be taking so long...
>
> It's simple: We have to read a lot of registers which we can only get
> to via I2C which is veeerrrrryyyyy sloooooowwwwww.
>
> But you bring up an interesting issue. 1.53s is larger than the 1s
> refresh rate of the driver. So the logic that prevents refreshes to
> occur faster than every second is pretty much useless. I think I
> should bump that value to at least 2s. Comments anyone?
To answer my own question: Never mind :-) I just realized that the 1s
refresh rate is measured between the end of an update cycle and the
begining of a new cycle.
So all is good.
...juerg
> ...juerg
>
>
> > Thanks,
> >
> > -Eric
> >
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> >
>
