On 02/11/14 09:26, Justin T. Gibbs wrote:
> On Jan 29, 2014, at 8:28 AM, Karl Pielorz <kpielorz_...@tdx.co.uk> wrote:
>> The man page for xen (man 4 xen) states you should have:
>> options NO_ADAPTIVE_SX
> The “NO_ADAPTIVE” settings are an optimization when running in environments 
> where different guests run on the same physical CPU.  However, many cloud 
> providers seem to statically pin CPUs to VMs, which means the adaptive lock 
> optimization works as expected.

... and with static pinning, adding the NO_ADAPTIVE_FOO options causes a
significant drop in performance, so you really don't want them unless you're
going to be sharing CPUs.

Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
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