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Re: [Qemu-devel] [PATCH 07/15] qapi: use mmap for QmpInputVisitor
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 07/15] qapi: use mmap for QmpInputVisitor |
Date: |
Tue, 28 Jun 2016 11:17:59 +0100 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
* Daniel P. Berrange (address@hidden) wrote:
> On Tue, Jun 28, 2016 at 11:39:03AM +0200, Peter Lieven wrote:
> > Am 28.06.2016 um 11:29 schrieb Dr. David Alan Gilbert:
> > > * Peter Lieven (address@hidden) wrote:
> > > > this struct is approx 75kB
> > > I wonder why it's so large.
> > >
> > > The stack size in QmpInputVisitor; it's got a 1024 element stack
> > > (QIV_STACK_SIZE) and I bet we never use anywhere near that.
> > >
> > > But even then that's 1024 * a 3 pointer stack object, 24 bytes -
> > > I don't see where the rest of that 75kB comes from.
> >
> > Sorry, I had a wrong size in mind. Its 24736 bytes. But thats
> > still larger than expecetd, right?
> >
> > > I'm a little wary about turning all these malloc's into mmap's
> > > because we do seem to use things like input visitors for small
> > > things; don't the cost of doing the mmap's add up in time
> > > instead of space?
> >
> > Sure, we should discuss this. The series should act as a base for
> > discussion.
> >
> > None of the things I changed into mmap are continously called
> > during VM runtime. So it most likely only happens at setup of the
> > vServer.
>
> QmpInputVisitor is used to parse all QMP monitor commands, so will
> be used continuously throughout life of QEMU, often very frequently.
> eg When migration is running many monitor commands per second are
> expected
Does the same input visitor get reused by each command?
Dave
>
> Regards,
> Daniel
> --
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--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH 11/15] qom: use mmap for bigger Objects, (continued)
[Qemu-devel] [PATCH 12/15] util: add a function to realloc mmapped memory, Peter Lieven, 2016/06/28
[Qemu-devel] [PATCH 09/15] loader: use mmap for ROMs, Peter Lieven, 2016/06/28
[Qemu-devel] [PATCH 07/15] qapi: use mmap for QmpInputVisitor, Peter Lieven, 2016/06/28
Re: [Qemu-devel] [PATCH 07/15] qapi: use mmap for QmpInputVisitor, Paolo Bonzini, 2016/06/28
Re: [Qemu-devel] [PATCH 07/15] qapi: use mmap for QmpInputVisitor, Markus Armbruster, 2016/06/30
[Qemu-devel] [PATCH 10/15] vmware_svga: use mmap for scratch pad, Peter Lieven, 2016/06/28
[Qemu-devel] [PATCH 04/15] coroutine: add a knob to disable the shared release pool, Peter Lieven, 2016/06/28
[Qemu-devel] [PATCH 05/15] util: add a helper to mmap private anonymous memory, Peter Lieven, 2016/06/28