Messages in this thread |  | | | Subject | RE: Latency traces I cannot interpret (sa1100, 2.6.15-rc7-rt1) | | Date | Fri, 30 Dec 2005 07:35:25 +0100 | | From | "kus Kusche Klaus" <> |
| |
> From: Daniel Walker > On Thu, 2005-12-29 at 16:08 +0100, kus Kusche Klaus wrote: > > I took some latency traces on our sa1100 (see attachment) running > > 2.6.15-rc7-rt1 with full preemption. > > They look very bad at the first glance, but I cannot > interpret them in > > detail. > > > > Trace 3, 4 and 5 seem to have obvious reasons: FPU emulation, > > Framebuffer console updates, and compression/decompression > of flash data > > for jffs2. > > > > Moreover, if I read these traces correctly, they just disable > > preemption, but still allow interrupts. Is that correct? > Can anything be > > done against these latencies, i.e. do they really need to disable > > preemption for such a long time? > > > > However, traces 1, 2, 6 and 7 are completely mysterious to me. > > Interrupts seem to be blocked for milliseconds, while > nothing is going > > on on the system? Moreover, there are console-related > function names in > > traces 6 and 7, although I've unconfigured the framebuffer > console for > > these runs! > > Do you have any power management features turned on? > > I've seen some traces that look like this on buggy intel x86 hardware. > When a small two line function with no loops lasts for 10ms . One of > your traces showed irq_exit() lasting 9ms . It's like the process just > stops.
No, no power management at all.
-- Klaus Kusche (Software Development - Control Systems) KEBA AG Gewerbepark Urfahr, A-4041 Linz, Austria (Europe) Tel: +43 / 732 / 7090-3120 Fax: +43 / 732 / 7090-6301 E-Mail: kus@keba.com WWW: www.keba.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |