stall-free memory reads ? (possibly stale) ?

[Slawa Olhovchenkov]

On Fri, Apr 08, 2016 at 06:24:16PM +0200, Luigi Rizzo wrote:

> Hi,
> I have an application with two threads sharing a memory variable,
> one continuously writing, one continuously reading.
> 
> Because of the way my system works, the reader can tolerate reading
> stale data, but it should not stall on memory reads (the line
> is on the local cache for the reader, just might be invalidated).
> 
> I was wondering if there is some way (either generic or
> x86-specific, either simple or convoluted, possibly using
> multiple versions of the shared variable in different cache
> lines) to make sure that reads never stalls (or, equivalently,
> let me read stale values from the cache) ?
> 
> I have done some experiments and on a single-socket machines
> the stallled reads take some 50ns; on a dual socket machine
> the stall penalty grows to about 200ns.

Can this link help to you?
https://tu-dresden.de/die_tu_dresden/zentrale_einrichtungen/zih/forschung/projekte/benchit/2015_ICPP_authors_version.pdf