Re: [Xen-devel] Atomic operations

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

The problem is that we dynamically remove LOCK_PREFIX when the guest has
only one vcpu. You need your own version of atomic.h in which you do not use
LOCK_PREFIX but use ?lock¹ directly instead. See
include/asm-i386/mach-xen/asm/sync_bitops.h for example, which is our
guaranteed inter-domain safe version of bitops.h.

 -- Keir

On 27/03/2009 17:22, "Timothy Hayes" <hayesti@xxxxxx> wrote:

> 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.



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