Re: [patch] voluntary-preempt-2.6.8.1-P3

Ingo Molnar
2004-08-18T12:32:40Z

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* Florian Schmidt <mista.tapas@gmx.net> wrote:

> Hi, it applied against 2.6.8.1 with some offsets and some buzz [?].
> Well anyways it compiled fine and the copy_page_range latency is
> gone.. Now i also see the extracty entropy thing, too..

could you try the attached patch that changes SHA_CODE_SIZE to 3 - does
this reduce the latency caused by extract_entropy?

> Btw: one question: at one point in time the IRQ handlers were in the
> SCHED_FIFO scheduling class. Why has this changed?

so that they dont starve the audio threads by default - the audio IRQ
has to get another priority anyway. Maybe we could try a default
SCHED_FIFO prio lower than the typical rt_priority of jackd - e.g. 30?

Ingo

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--- linux/drivers/char/random.c.orig
+++ linux/drivers/char/random.c
@@ -942,7 +942,7 @@ EXPORT_SYMBOL(add_disk_randomness);
#define HASH_TRANSFORM SHATransform

/* Various size/speed tradeoffs are available. Choose 0..3. */
-#define SHA_CODE_SIZE 0
+#define SHA_CODE_SIZE 3

/*
* SHA transform algorithm, taken from code written by Peter Gutmann,