Re: [Xen-devel] Atomic operations

[Timothy Hayes <hayesti@xxxxxx>]

My domU kernels are configured with:

CONFIG_SMP=y
CONFIG_X86_FIND_SMP_CONFIG=y
CONFIG_X86_MPPARSE=y
# CONFIG_X86_PC is not set
CONFIG_X86_XEN=y

The problem occurs when I limit the VCPUs in each guest to 1, presumably they get scheduled into unique physical CPUs in parallel. Is there anything else I should be aware of? I'm quite optimistic that the XenSocket logic is sound, the only thing I can attribute this to is a lack of atomicity.

Tim

2009/3/26 Keir Fraser <keir.fraser@xxxxxxxxxxxxx>

On 26/03/2009 07:34, "Juergen Gross" <juergen.gross@xxxxxxxxxxxxxxxxxxx>
wrote:

> Keir Fraser wrote:
>> The Linux atomic.h operations will be atomic even across domains.
>
> ... unless CONFIG_SMP was not defined in the domU kernel build.

Yes, good point. Actually I assumed the OP was copying atomic.h for his own
use, but he probably isn't actually. And either way the CONFIG_SMP ifdef'ery
could bite.

 -- Keir

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