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Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debuggin
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases |
Date: |
Fri, 10 May 2013 09:39:04 -0500 |
User-agent: |
Notmuch/0.15.2+77~g661dcf8 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
Paolo Bonzini <address@hidden> writes:
> Il 10/05/2013 15:23, Andreas Färber ha scritto:
>> Am 10.05.2013 15:08, schrieb Paolo Bonzini:
>>> Il 10/05/2013 15:01, Anthony Liguori ha scritto:
>>>> I'd prefer not to disable but instead focus on improving performance.
>>>
>>> For 1.5? This is a regression in 1.5 due to more and more usage of
>>> foo_env_on_cpu.
>>
>> If CPUs were the only reason, we could simply change those inlines and
>> ENV_GET_CPU() macro to use a C cast. No complicated interface scenarios
>> requiring a dynamic cast are used for CPUs so far to my knowledge.
>
> Almost nothing really requires a dynamic cast in QEMU. Only interface
> casts do, and there's just a couple of uses of interfaces.
>
> And I wrote in the cover letter that what I want is really avoid the
> need for "fast casts" in the hot paths.
>
> Can you guys actually read the commit messages?
Yeah, the vast majority of the series is a nice cleanup.
I just oppose the notion of disabling casts and *especially* only
disabling casts for official builds.
I don't see a reason to do something like this without even attempting
to improve performance first.
Regards,
Anthony Liguori
>> Either way, it would be nice to see the call sites of those
>> most-impacting dynamic casts! So far I held back my APIC RFC since I'm
>> not sure how to reproducibly profile things.
>
> It's interrupts (both sending and returning from them).
>
> Paolo
- [Qemu-devel] [PATCH for-1.5 7/9] build: disable QOM cast debugging for official releases, (continued)
- [Qemu-devel] [PATCH for-1.5 7/9] build: disable QOM cast debugging for official releases, Paolo Bonzini, 2013/05/10
- [Qemu-devel] [PATCH for-1.5 6/9] qom: allow turning cast debugging off, Paolo Bonzini, 2013/05/10
- [Qemu-devel] [PATCH for-1.5 8/9] qom: simplify object_class_dynamic_cast, part 1, Paolo Bonzini, 2013/05/10
- [Qemu-devel] [PATCH for-1.5 9/9] qom: simplify object_class_dynamic_cast, part 2, Paolo Bonzini, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Anthony Liguori, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Paolo Bonzini, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Andreas Färber, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Paolo Bonzini, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Aurelien Jarno, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases,
Anthony Liguori <=
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Paolo Bonzini, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Anthony Liguori, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Aurelien Jarno, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Anthony Liguori, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Paolo Bonzini, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Anthony Liguori, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Paolo Bonzini, 2013/05/11
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Aurelien Jarno, 2013/05/11
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Anthony Liguori, 2013/05/10
- Re: [Qemu-devel] [PATCH for-1.5 0/9] Disable expensive QOM cast debugging for official releases, Aurelien Jarno, 2013/05/10