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From: Artyom Tarasenko <atar4qemu@googlemail.com>
To: Blue Swirl <blauwirbel@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>
Subject: [Qemu-devel] Re: irq latency and tcg
Date: Wed, 9 Dec 2009 13:30:24 +0100	[thread overview]
Message-ID: <fb8d4f70912090430k2ce186fvc1d3ea3aed832cd3@mail.gmail.com> (raw)
In-Reply-To: <f43fc5580912071008q1a072f29x27678ea69a7a5ee0@mail.gmail.com>

2009/12/7 Blue Swirl <blauwirbel@gmail.com>:
> On Mon, Dec 7, 2009 at 3:30 PM, Artyom Tarasenko
> <atar4qemu@googlemail.com> wrote:
>> Can it be that qemu (-system-sparc in my case, but I guess it's more
>> or less similar on all platforms) reacts to irqs slower than a real
>> hardware due to tcg optimizations?
>>
>> I see one test pattern which fails on qemu:
>>
>> <cause an interrupt>
>> nop * N
>> <check whether the interrupt happened>
>>
>> What I observe is that the proper interrupt does take a place, but
>> after the check, so no-one expects it anymore.
>> Is there a way to reduce the interrupt latency? Or maybe there is a
>> good substitute to a nop*N, so that irq would definitely get through
>> in the mean time?
>
> On Sparc, nops do not generate any code at all.

But "qemu: fatal: Raised interrupt while not in I/O function" is still
a bug, right?

  reply	other threads:[~2009-12-09 12:30 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-07 13:30 [Qemu-devel] irq latency and tcg Artyom Tarasenko
2009-12-07 15:06 ` Paul Brook
2009-12-07 17:39   ` Artyom Tarasenko
2009-12-07 17:44     ` Paul Brook
2009-12-07 18:08 ` [Qemu-devel] " Blue Swirl
2009-12-09 12:30   ` Artyom Tarasenko [this message]
2009-12-12  8:46     ` Blue Swirl
2009-12-12 23:29       ` Paul Brook

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