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SubjectCost of an IRQ


how expensive is to return from an IRQ handler, obtain another
IRQ (in my case coming from the ISA bus) and enter the IRQ handler again?

I need this for the COSA driver - COSA can tell me if it is able
to transfer another packet, so I can rerun another iteration of the
IRQ handler and save one IRQ (as described above), but I need to wait for
~ 5-10 usecs in IRQ handler for it. Is it better to do udelay(10)
in IRQ handler, or to return from the handler and wait for another IRQ?

The COSA card is primarily dedicated for routers, so it doesn't matter
that in those 10 usecs CPU can do something other.


\ Jan "Yenya" Kasprzak <kas at>
\\ PGP: finger kas at 0D99A7FB206605D7 8B35FCDE05B18A5E //
\\\ Czech Linux Homepage: ///
/// Can you say "ignored email" three times quickly while chewing \\\
// on an apple? --Linus Torvalds \\
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