get info in a loop from a sysfs entry
Wouter Simons
lkml at woutersimons.org
Wed Jan 5 03:35:39 EST 2011
On 01/04/2011 04:52 PM, Dave Hylands wrote:
> On Tue, Jan 4, 2011 at 2:48 AM, Wouter Simons <lkml at woutersimons.org> wrote:
>>
>> for (i = 0; i < count; i++) {
>> if (fscanf(fd_next, "0x%X", &sample) != 1) { /* No data */
>> continue;
>> }
>
> I would change this to use unbuffered I/O routines (i.e.
> open/read/lseek/close) and use sscanf rather than fscanf.
> fopen/fread/fseek/fclose use buffering by default.
>
> That would eliminate any buffering that the user side runtime library
> is doing. I suspect that because the data is buffered by the FILE *
> routines, even doing the seek is just re-returning the data that was
> read the first time around.
Thanks Dave, a quick test application shows that your solution works
perfectly. This saves me a lot of overhead!
Best regards,
Wouter
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