From: Programmingkid <programmingkidx@gmail.com>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Alex Bennée" <alex.bennee@linaro.org>,
incoming+qemu-project-qemu-11167699-3xhw7c0pviow7og92yv73e0tr-issue-404@incoming.gitlab.com,
"QEMU devel list" <qemu-devel@nongnu.org>
Subject: Re: tb_flush() calls causing long Windows XP boot times
Date: Wed, 16 Jun 2021 08:12:15 -0400 [thread overview]
Message-ID: <CB323D41-288A-47DD-9AEC-35B1BA7C580F@gmail.com> (raw)
In-Reply-To: <9d0b277d-415f-0f4e-3f09-03445f89848f@linaro.org>
> On Jun 15, 2021, at 9:58 PM, Richard Henderson <richard.henderson@linaro.org> wrote:
>
> On 6/15/21 6:58 AM, Programmingkid wrote:
>>> Ahh I misread - so those are the addresses of the routines and not where
>>> it's sticking the breakpoint?
>>>
>>> I notice from a bit of googling that there is a boot debugger. I wonder
>>> if /nodebug in boot.ini stops this behaviour?
>>>
>>> https://docs.microsoft.com/en-us/troubleshoot/windows-server/performance/switch-options-for-boot-files
>>>
>>> --
>>> Alex Bennée
>> Hi Alex,
>> I tried your suggestion of using /nodebug. It did not stop the tb_flush() function from being called.
>
> We are not expecting zero calls to tb_flush (it is used for other things, including buffer full), but we are hoping that it reduces the frequency of the calls.
Agreed.
> I'm guessing you didn't immediately see the slowdown vanish, and so there was no change to the frequency of the calls.
Correct.
> FWIW, if you switch to the qemu console, you can see how many flushes have occurred with "info jit".
Thank you very much for this information.
I'm currently learning about the x86's debug registers D0 to D7. There are a lot of rules associated with them. So my guess is one or more rules may not be implemented in QEMU. I will try to test them out in FreeDOS and compare notes with a real x86 CPU.
A possible workaround might be to implement a command line option that allows the user to specify how often the tb_flush() call is made. When I eliminated the call I could not find any problems with my VM's. I understand if this is not possible.
next prev parent reply other threads:[~2021-06-16 12:13 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 12:59 tb_flush() calls causing long Windows XP boot times Programmingkid
2021-06-10 13:14 ` Peter Maydell
2021-06-10 13:24 ` Mark Cave-Ayland
2021-06-11 11:24 ` Alex Bennée
2021-06-11 15:01 ` Programmingkid
2021-06-11 17:13 ` Paolo Bonzini
2021-06-11 18:22 ` Alex Bennée
2021-06-13 14:03 ` Mark Cave-Ayland
2021-06-14 14:37 ` Alex Bennée
2021-06-15 13:58 ` Programmingkid
2021-06-16 1:58 ` Richard Henderson
2021-06-16 8:59 ` Mark Cave-Ayland
2021-06-16 12:53 ` Alex Bennée
2021-06-16 13:06 ` Peter Maydell
2021-06-16 15:30 ` Alex Bennée
2021-06-16 13:21 ` Alex Bennée
2021-06-16 12:12 ` Programmingkid [this message]
2021-06-10 13:38 ` Programmingkid
2021-06-14 22:19 ` no-reply
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