> From: Bartlomiej Zolnierkiewicz [mailto:[EMAIL PROTECTED] > > On Wed, 30 Mar 2005 13:52:05 +0200, kus Kusche Klaus > <[EMAIL PROTECTED]> wrote: > > However, things break seriously when exercising the CF card > in parallel > > (e.g. with a dd if=/dev/hda of=/dev/null): > > > > * The rtc *interrupt handler* is delayed for up to 250 > *micro*seconds. > > This is very bad for my purpose, but easy to explain: It is > roughly the > > time needed to transfer 512 Bytes from a CF card which can > transfer 2 > > Mbyte/sec, and obviously, the CPU blocks all interrupts > while making pio > > > > transfers. (Why? Is this really necessary?) > > > > (I know because I instrumented the rtc irq handler with > rdtscl(), too) > > hdparm -u1 /dev/hda > > should help
Hmmm, thanks, that sounds very reasonable, and I didn't know that flag. Unfortunately, it doesn't help. The bad timings stay the same (still delays in the 30-300 ms range), the number of context switches stays the same, ... The only thing which changes is the CPU load shown by vmstat: * With -u0, I have 1 % user, ~50 % sys, ~50 % wa * With -u1, I have 1 % user, ~98 % sys, 1 % wa P.S.: Apologies for my badly formatted mails. The company forces us to use outlook, we may not even change the settings... Klaus Kusche >Entwicklung Software - Steuerung >Software Development - Control > >KEBA AG >A-4041 Linz >Gewerbepark Urfahr >Tel +43 / 732 / 7090-3120 >Fax +43 / 732 / 7090-8919 >E-Mail: [EMAIL PROTECTED] >www.keba.com > - 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/
