[dpdk-dev] [PATCH v7 3/7] eal: add power monitor for multiple events

[David Hunt]

On 7/7/2021 11:48 AM, Anatoly Burakov wrote:
> Use RTM and WAITPKG instructions to perform a wait-for-writes similar to
> what UMWAIT does, but without the limitation of having to listen for
> just one event. This works because the optimized power state used by the
> TPAUSE instruction will cause a wake up on RTM transaction abort, so if
> we add the addresses we're interested in to the read-set, any write to
> those addresses will wake us up.
>
> Signed-off-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
> Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
> ---
>
> Notes:
>      v4:
>      - Fixed bugs in accessing the monitor condition
>      - Abort on any monitor condition not having a defined callback
>      
>      v2:
>      - Adapt to callback mechanism
>

Initially I had issues running this as I couldn't see the "rtm" flag in 
/proc/cpuinfo, but adding "tsx=on" to the kernel parameters resolved 
this, and rtm was then available to use. Once this was done, I was then 
able to successfully see power saving when a core was configuired with 
multiple queues.

Tested-by: David Hunt <david.hunt at intel.com>