Messages in this thread | | | Date | Tue, 24 Jul 2007 11:20:33 +0200 | From | John Sigler <> | Subject | Re: Pin-pointing the root of unusual application latencies |
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John Sigler wrote:
> ( check_dektec_in-1095 |#0): new 271 us user-latency. > ( check_dektec_in-1095 |#0): new 275 us user-latency. > ( check_dektec_in-1095 |#0): new 290 us user-latency. > ( check_dektec_in-1095 |#0): new 297 us user-latency. > ( check_dektec_in-1095 |#0): new 345 us user-latency. > ( check_dektec_in-1095 |#0): new 358 us user-latency. > ( check_dektec_in-1095 |#0): new 384 us user-latency. > ( check_dektec_in-1095 |#0): new 392 us user-latency. > ( check_dektec_in-1095 |#0): new 395 us user-latency. > ( check_dektec_in-1095 |#0): new 396 us user-latency. > ( check_dektec_in-1095 |#0): new 1031 us user-latency. > ( check_dektec_in-1095 |#0): new 1100 us user-latency. > ( check_dektec_in-1095 |#0): new 1105 us user-latency. > ( check_dektec_in-1095 |#0): new 1106 us user-latency. > > Here's the function trace for the 1106-µs latency: > > http://linux.kernel.free.fr/latency/1106-us-trace.txt
The function trace for 400-µs latencies is different:
( check_dektec_in-1145 |#0): new 275 us user-latency. ( check_dektec_in-1145 |#0): new 276 us user-latency. ( check_dektec_in-1145 |#0): new 288 us user-latency. ( check_dektec_in-1145 |#0): new 289 us user-latency. ( check_dektec_in-1145 |#0): new 289 us user-latency. ( check_dektec_in-1145 |#0): new 290 us user-latency. ( check_dektec_in-1145 |#0): new 297 us user-latency. ( check_dektec_in-1145 |#0): new 345 us user-latency. ( check_dektec_in-1145 |#0): new 354 us user-latency. ( check_dektec_in-1145 |#0): new 377 us user-latency. ( check_dektec_in-1145 |#0): new 393 us user-latency.
http://linux.kernel.free.fr/latency/393-us-trace.txt
There are ~200 calls to ioread32 from mdio_read from speedo_timer.
http://lxr.linux.no/source/drivers/net/eepro100.c#L1159 http://lxr.linux.no/source/drivers/net/eepro100.c#L928
In this case, and as far as I understand, the culprit is the eepro100 driver talking to one of the NICs (which one?). Is that correct?
What is the consequence of IRQ10 being shared by eth2 and by my I/O board?
How can I force Linux to assign different IRQs to every peripheral if I have free IRQs lines?
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