On 2014-08-31 11:53, Hannu Nyman wrote: > > This could be a problem caused by mips16. We use that in BB to create > smaller binaries. but Jonas saw a performance problem in some > applications, mostly stuff doing crypto (big integer calculations). > > Have developers evaluated the pros and cons of using mips16 as the default? Yes
> It was made the default along the switch to gcc4.8, but I do not remember > seeing any extensive discussion about that change. Yes, it produces smaller > binaries, but apparently with a visible performance hit. Most binaries are not performance sensitive > The performance problems can materialize in strange ways, e.g. ssh login time > to dropbear doubled (increased by several seconds), > https://dev.openwrt.org/ticket/15209 . So, it is not just about gradual > performance hit, but it can apparently cause visible annoyances. Right. We should simply identify binaries where mips16 is causing problems and disable it for those. > Now that the performance issues have been noticed, is there any plan for > developers to systematically go through the core apps to check the impact and > turn mips16 off for problematic apps? I guess that based by evedence so far, > it might be turned off for all math-intensive apps like crypto libraries, but > there may be also others (maybe voice & image encoding/decoding?) > > To have small binaries is nice, but I guess that a growing amount of Openwrt > users are power users with modern routers with more flash space and having > interest for VPNs etc. And for them mips16 may have brought more trouble than > benefits. I think only a small portion of our packages seem to have problems with mips16, and turning it off selectively is very easy - so I don't consider this a big deal. I think it makes sense to simply wait for bug reports to show up and deal with those on a case by case basis. If we delay using mips16 until core devs have gone through every single package, it will never get done... - Felix _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
