Hi...yesterday i was reading the understanding linux kernel and the linux kernel development. I have found that at boot time the kernel programmes the irq0 to a tick rate of 1 ms for 2.6 linux kernel and 10ms for 2.4 kernel...
Also the articles that i have read said that the kernel updates the system clock
each 1 msec. I was wondering then how the kernel is possible to keep
microsecond timestamps for the packets coming in an interface? How can calulate
the time when the basic timer is only at 1 millisecond?
I have also read for the
struct timespec { time_t tv_sec; /* seconds */ long tv_nsec; /* nanoseconds */ };
timespec struct that has a nanosecond field.. How the kernel can insert data to that field and how it can calculate the nanoseconds have passed?? Thx..as u can understand i am very confused about time related issues...so plz shed as much ligh as u can.. Thx a lot Alex Paleos
----------------------------------------------------------------
This message was sent through the TEI of ATHENS by means of NOC. -
: send the line "unsubscribe linux-net" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
IIRC Most arches have a free running counter that has nanosecond granularity. You just read it when a packet arrives and can use that to calculate very small amounts of time.
Neil -- /*************************************************** *Neil Horman *Software Engineer *Red Hat, Inc. *nhorman@xxxxxxxxxx *gpg keyid: 1024D / 0x92A74FA1 *http://pgp.mit.edu ***************************************************/ - : send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
