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SubjectRe: Short question regarding generic_make_request()

On Sun, 3 Feb 2002, Steffen Persvold wrote:

> Ok, the reason I'm asking is that I receive a request from a remote
> machine on interrupt level (tasklet) and want to submit this to the
> local device. The reason I'm using a tasklet instead of a kernel
> thread is that somewhere between RedHat's 2.4.3-12 and 2.4.9-12
> kernels the latency of waking up a kernel thread increased (using a
> semaphore method similar to the one used in loop.c). I don't know why
> this happened, but I guess that if I still could use a kernel thread
> there wouldn't be any problems using generic_make_request().

you really want a kernel thread for this. The wakeup latency of a kernel
thread is on the order of 2-3 usecs (context switch overhead included),
nothing compared to usual block IO costs.

you say that the latency of waking up a kernel thread has increased - by
how much?

Ingo

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