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Message-id: <53ADCD3B.3000209@samsung.com> Date: Fri, 27 Jun 2014 13:59:55 -0600 From: Shuah Khan <shuah.kh@...sung.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: gregkh@...uxfoundation.org, keescook@...omium.org, michael@...erman.id.au, fweisbec@...il.com, benh@...nel.crashing.org, linux-kernel@...r.kernel.org, Shuah Khan <shuah.kh@...sung.com> Subject: Re: [PATCH] tools: selftests - create a separate hotplug target On 06/27/2014 01:45 PM, Andrew Morton wrote: > On Fri, 27 Jun 2014 11:10:37 -0600 Shuah Khan <shuah.kh@...sung.com> wrote: > >> On 06/26/2014 03:51 PM, Andrew Morton wrote: >>> On Thu, 26 Jun 2014 14:33:56 -0600 Shuah Khan <shuah.kh@...sung.com> wrote: >>> >>>> On some systems, hotplug tests could hang forever waiting for cpu and >>>> memory to be ready to be offlined. A special hotplug target is created, >>>> which will help run non-hotplug tests and run hotplug tests as a special >>>> case. Individual hotplug tests can still be run as a special target >>>> targeted for a single subsystem. >>> >>> This is a bit sad. The general philosophy with selftests is that they >>> should run to completion even if the kernel/hardware which they are >>> testing isn't available - they should work it out for themselves. >>> >>> But that's obviously a problem with hotplug. And with networking or >>> anything else which needs external action. >>> >>> On the other hand, networking has loopback and the kernel supports cpu >>> hotplug simulation via procfs. So perhaps the cpu and memory hotplug >>> tests should be redone so they do the plug/unplug injection themselves, >>> so they can run without external intervention? >> >> Changing/running the tests in a safe mode (least possibility of hang) >> mode is another option. This way the tests are run in normal mode with >> reduced scope. Memory hotplug test has the ratio option and when I >> specified low ratio 1-5%, it completed in a few seconds. >> >> cpu-hotplug test will require changes. I am working on a change to >> offline a user specified # of cpus instead offlining all hotpluggable >> cpus and then onlining them again at the end of the test. >> >> When all selftests are run, safe mode hotplug tests will be run. >> >> Does this approach sound reasonable? > > I don't know really. You know more about this than I - what advantages > does the separate-make-target approach have over this approach? > Currently these tests run with full range - i.e try to offline all cpus that are hotpluggable and try to offline all memory that is hotpluggable. This results in hangs. Creating a separate target the way I did it in this patch excludes these tests all together. i.e when somebody runs: make -C tools/testing/selftests run_tests hotplug tests don't run. Instead, with a few changes, tests can be run with a reduced scope so a % of the memory gets offlined as opposed to all of it and the same thing with cpus. This way hotplug code gets tested as opposed to being excluded in a default test run case. However, if limited scope testing isn't useful, separate target is better until tests can be made safe to run without hangs. -- Shuah -- Shuah Khan Senior Linux Kernel Developer - Open Source Group Samsung Research America(Silicon Valley) shuah.kh@...sung.com | (970) 672-0658 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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