On Sun, 17 Oct 2021, Randy Dunlap wrote: > On 10/17/21 11:12 AM, Julia Lawall wrote: > > Hello, > > > > If I do the following: > > > > git clean -dfx > > cp saved_config .config > > make olddefconfig && make && make modules_install && make install > > > > Should I always end up with the same kernel, regardless of the kernel that > > is currently running on the machine? > > > > I see a large performance difference between Linux 5.10 and all versions > > afterwards for a particular benchmark. I am unable to bisect the problem > > eg between 5.10 and 5.11, because as soon as I come to a kernel that gives > > the bad performance, all of the kernels that I generate subsequently in > > the bisecting process (using the above commands) also have the bad > > performance. > > > > It could of course be that I have completely misinterpreted the problem, > > and it has nothing to do with the kernel. But I have tested the program a > > lot when only working on variants of Linux 5.9. I only start to have > > problems when I use versions >= 5.11. > > Hi, > > My "guess" is that this has something to do with the build > reusing some current file(s) that need to be rebuilt. > I.e., adding a "make clean" or "make proper" might be needed. This was my guess too. But I have the git clean -dfx. I did a comparison with make distclean and this does a little more (mostly some files in tools). thanks, julia > > I say this only because sometimes I cannot even reproduce > a build that has errors or warnings unless I prefix it with > make clean or mrproper. (i.e., nothing to do with booting > and running the new kernel) > Even though the .config file has changed and I do > "make olddefconfig", the same build errors do not show up > unless I do the clean or mrproper step also. > > > -- > ~Randy >
