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Re: [Qemu-devel] Error handling in realize() methods
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] Error handling in realize() methods |
Date: |
Wed, 9 Dec 2015 13:21:09 +0000 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
* Peter Maydell (address@hidden) wrote:
> On 9 December 2015 at 10:29, Dr. David Alan Gilbert <address@hidden> wrote:
> > (OK, to be honest I think we should protect every allocation - but I do
> > have sympathy with the complexity/testing arguments).
>
> My view on this is that Linux overcommits, so the actual likely
> way that "oops, out of memory" will manifest is by some page not
> being able to be allocated-on-demand, at which point your process
> is toast anyway. Checking malloc returns is really only checking
> your virtual address space allocation, which typically speaking
> always succeeds, except in the "we tried to get gigabytes at
> once" case...
We already get some failures, e.g. qemu-system-x86_64 -m 8192
fails with an allocation error on my laptop (8GB RAM+2GB swap).
I'm also not sure whether your statement is true once things like
cgroup/ulimit memory restrictions are used and/or mlock.
People really really hate OOM behaviour in production systems
and jump through hoops to try and avoid it.
Dave
>
> thanks
> -- PMM
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] Error handling in realize() methods, Markus Armbruster, 2015/12/08
- Re: [Qemu-devel] Error handling in realize() methods, Markus Armbruster, 2015/12/10
- Re: [Qemu-devel] Error handling in realize() methods, Paolo Bonzini, 2015/12/09
- Re: [Qemu-devel] Error handling in realize() methods, Dr. David Alan Gilbert, 2015/12/09
- Re: [Qemu-devel] Error handling in realize() methods, Paolo Bonzini, 2015/12/09
- Re: [Qemu-devel] Error handling in realize() methods, Markus Armbruster, 2015/12/10
- Re: [Qemu-devel] Error handling in realize() methods, Dr. David Alan Gilbert, 2015/12/10
- Re: [Qemu-devel] Error handling in realize() methods, Paolo Bonzini, 2015/12/10
- Re: [Qemu-devel] Error handling in realize() methods, Paolo Bonzini, 2015/12/10
- Re: [Qemu-devel] Error handling in realize() methods, Markus Armbruster, 2015/12/10