On 1/26/22 12:13 AM, Petr Vorel wrote:
Hi all,
on 2022/1/26 4:33, Shuah Khan wrote :
On 12/15/21 2:56 AM, Yang Xu wrote:
Since kernel commit 43209ea2d17a ("zram: remove max_comp_streams internals"), zram has switched to per-cpu streams. Even kernel still keep this interface for some reasons, but writing to max_comp_stream doesn't take any effect. So remove it.
I get that max_comp_stream doesn't do anything since this referenced commit. Don't we need this test on older kernels since older kernels still support max_comp_stream?
I read the following info from kernel selftest documentation https://www.kernel.org/doc/html/latest/dev-tools/kselftest.html
"The kernel contains a set of “self tests” under the tools/testing/selftests/ directory. These are intended to be small tests to exercise individual code paths in the kernel. Tests are intended to be run after building, installing and booting a kernel."
So, we can build older kernel(use older kernel source) if we want to test older kernel.
IMO, kernel selftest is different from other testsuit(ie ltp, this shuould think about api changes because ltp may test on different kernel).
Yes, that's how I understand the difference with approach of in kselftest - the kernel tree testsuite and LTP - the out-of-tree testsuite.
Removing max_comp_stream test appears to be motivated by the fact it isn't needed on newer kernels.
Kselftest from mainline can be run on older stable kernels. This is a use-case for a lot test rings. The idea is that when a new test gets added for older code to regression test a bug, we should be able to run that test on an older kernel. This is the reason why we don't remove code that can still test an older kernel and make sure it skips gracefully.
Thanks for clarifying this approach. It might be worth of documenting it in dev-tools/kselftest.rst.
Kind regards, Petr
Hence, I won't be taking this patch.
thanks, -- Shuah