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Date:   Wed, 26 Jan 2022 08:13:10 +0100
From:   Petr Vorel <pvorel@suse.cz>
To:     "xuyang2018.jy@fujitsu.com" <xuyang2018.jy@fujitsu.com>
Cc:     Shuah Khan <skhan@linuxfoundation.org>,
        "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>,
        "shuah@kernel.org" <shuah@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "naresh.kamboju@linaro.org" <naresh.kamboju@linaro.org>,
        "aleksei.kodanev@bell-sw.com" <aleksei.kodanev@bell-sw.com>
Subject: Re: [PATCH 1/3] selftests/zram: Remove obsolete max_comp_streams
 interface
Message-ID: <YfD0hiUSf40jX82d@pevik>
Reply-To: Petr Vorel <pvorel@suse.cz>
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 <1146337d-718e-a369-1012-224f06bc9c2f@linuxfoundation.org>
 <61F0D9F7.1080200@fujitsu.com>
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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.

Kind regards,
Petr

> Also cc ltp co-maintainer Petr

> Or, did I miss something?

> Best Regards
> Yang Xu


> > thanks,
> > -- Shuah