Please don't send emails which contain 500-column lines? Venkatesh Pallipadi <[EMAIL PROTECTED]> wrote: > > Current tsc based delay_calibration can result in significant errors in > loops_per_jiffy count when the platform events like SMIs (System Management > Interrupts that are non-maskable) are present.
This seems like an unsolveable problem. > Solution: > The patch below makes the calibration routine aware of asynchronous events > like SMIs. We increase the delay calibration time and also identify any > significant errors (greater than 12.5%) in the calibration and notify it > to user. Like to know your comments on this. I find calibrate_delay_tsc() quite confusing. Are you sure that the variable names are correct? + tsc_rate_max = (post_end - pre_start) / DELAY_CALIBRATION_TICKS; + tsc_rate_min = (pre_end - post_start) / DELAY_CALIBRATION_TICKS; that looks strange. I'm sure it all makes sense if one understands the algorithm, but it shouldn't be this hard. Please reissue the patch with adequate comments which describe what the code is doing. Shouldn't calibrate_delay_tsc() be __devinit? (That may generate warnings from reference_discarded.pl, but they're false positives) >From a maintainability POV it's not good that x86 is no longer using the generic calibrate_delay() code. Can you rework the code so that all architectures must implement arch_calibrate_delay(), then provide stubs for all except x86? After all, other architectures/platforms may have the same problem. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
