On 14/09/15 12:32, Arnd Bergmann wrote: > On Monday 14 September 2015 13:04:59 Roger Pau Monné wrote: >>> TBH, I'm expecting a small impact to the performance. It would be hard >>> to get the exactly the same performance as today if we keep the helpers >>> to avoid the backend dealing himself with the splitting and page >>> granularity. >>> >>> Although, if the performance impact is not acceptable, it may be >>> possible to optimize gnttab_foreach_grant_in_range by moving the >>> function inline. The current way to the loop is the fastest I've found >>> (I've wrote a small program to test different way) and we will need it >>> when different of size will be supported. >> >> I don't expect the performance to drop massively with this patches >> applied, but it would be good to al least have an idea of the impact. > > Note that using 64kb pages in Linux tends to destroy performance > in Linux in any case, as the memory consumption for most workloads > explodes. In a virtualized environment you already tend to be > memory constrained, so any measurement should take that into account > and put the extra overhead into perspective to the massive overhead > of running 64kb pages when RAM is tight.
If this is the case, why are some distros using 64 KiB pages then? David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
