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Subject: Re: [RFC PATCH 00/13] x86 User Interrupts support
To:     Stefan Hajnoczi <stefanha@redhat.com>,
        Sohil Mehta <sohil.mehta@intel.com>,
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From:   Richard Henderson <richard.henderson@linaro.org>
Message-ID: <3abdadab-9b7e-7cc0-5ec5-17fa385ce7d4@linaro.org>
Date:   Fri, 1 Oct 2021 12:41:59 -0400
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On 10/1/21 12:35 PM, Stefan Hajnoczi wrote:
> QEMU's TCG threads execute translated code. There are events that
> require interrupting these threads. Today a check is performed at the
> start of every translated block. Most of the time the check is false and
> it's a waste of CPU.
> 
> User interrupts can eliminate the need for checks by interrupting TCG
> threads when events occur.

We used to use interrupts, and stopped because we need to wait until the guest is in a 
stable state.  The guest is always in a stable state at the beginning of each TB.

See 378df4b2375.


r~