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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 08:01:40 -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:
> Cast debugging can have a substantial cost (20% or more, measured by
> Aurelien on qemu-system-ppc64).
[Needs citation]
> Instead of adding special-cased "fast
> casts" in the hot paths, we can just disable it in releases. At the
> same time, add tracing facilities that simplify the analysys of those
> problems that cast debugging would reveal.
I'd prefer not to disable but instead focus on improving performance.
I suspect any performance overhead is resolving the type string to
typeimpl. One work around is to have a dynamic cast that takes a
typeimpl and then use a function that returns a static similar to how
glib works.
If you've got a reproducible case where the overhead is high, it should
be easy to check.
Regards,
Anthony Liguori
>
> At least patches 1-7 are for 1.5.
>
> Paolo Bonzini (9):
> qom: improve documentation of cast functions
> qom: allow casting of a NULL class
> qom: add a fast path to object_class_dynamic_cast
> qom: pass file/line/function to asserting casts
> qom: trace asserting casts
> qom: allow turning cast debugging off
> build: disable QOM cast debugging for official releases
> qom: simplify object_class_dynamic_cast, part 1
> qom: simplify object_class_dynamic_cast, part 2
>
> configure | 20 ++++++++------
> include/qom/object.h | 40 ++++++++++++++++++++++-----
> qom/object.c | 77
> ++++++++++++++++++++++++++++++++++------------------
> trace-events | 3 ++
> 4 files changed, 99 insertions(+), 41 deletions(-)
>
> --
> 1.8.1.4
- [Qemu-devel] [PATCH for-1.5 1/9] qom: improve documentation of cast functions, (continued)
- [Qemu-devel] [PATCH for-1.5 1/9] qom: improve documentation of cast functions, Paolo Bonzini, 2013/05/10
- [Qemu-devel] [PATCH for-1.5 2/9] qom: allow casting of a NULL class, Paolo Bonzini, 2013/05/10
- [Qemu-devel] [PATCH for-1.5 3/9] qom: add a fast path to object_class_dynamic_cast, Paolo Bonzini, 2013/05/10
- [Qemu-devel] [PATCH for-1.5 4/9] qom: pass file/line/function to asserting casts, Paolo Bonzini, 2013/05/10
- [Qemu-devel] [PATCH for-1.5 5/9] qom: trace asserting casts, Paolo Bonzini, 2013/05/10
- [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 <=
- 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, 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, 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