On 8/26/2020 5:41 PM, Bruce Richardson wrote: > On Wed, Aug 26, 2020 at 05:33:20PM +0100, Ferruh Yigit wrote: >> On 7/14/2020 10:51 PM, Dharmik Thakkar wrote: >>> Meson build system lacks support for >>> CONFIG_RTE_TEST_PMD_RECORD_CORE_CYCLES and >>> CONFIG_RTE_TEST_PMD_RECORD_BURST_STATS configuration options. >>> >>> One solution is to add these options within meson_options.txt >>> >>> Since adding these as runtime config causes no performance impact, >> >> Hi Dharmik, >> >> These are on the datapath, and even disable there will be additional >> checks, isn't it expected to have some impact? Did you do any >> measurements for it? >> > Branches that always predict the same way can be very cheap, and unless > proven to be a problem, I'd see no issue with having a few on the datapath > - especially if it just one or two per burst. If we start seeing a > significant number, or ones that occur for every packet, then we perhaps > need to be more cautious. > > I also think that using lots of different CFLAGS for turning things on and > off is as bad - or even worse - than using the old build-time config > options, just this time we don't have a single list of them somewhere! > Therefore, I think we really need to start converting these to runtime > options where we can.
+1 using config options via 'CFLAGS' is worse. But if we want it to be compile time option because of performance, this is an option.
