Date: Fri, 5 Jul 2019 21:37:22 +0000 From: Rick Macklem <rmacklem@uoguelph.ca> To: Alan Somers <asomers@freebsd.org> Cc: "freebsd-current@FreeBSD.org" <freebsd-current@FreeBSD.org>, "kib@freebsd.org" <kib@FreeBSD.org> Subject: Re: test program for copy_file_range(2) Message-ID: <YTXPR01MB0285A8C209354AC5089776AEDDF50@YTXPR01MB0285.CANPRD01.PROD.OUTLOOK.COM> In-Reply-To: <CAOtMX2g65aOraEtzM3eU9fqdZ1qtfDbV5YWiZUMvW67O%2BODKJQ@mail.gmail.com> References: <YTXPR01MB02854ED77B07C7434C2F442EDDF50@YTXPR01MB0285.CANPRD01.PROD.OUTLOOK.COM> <CAOtMX2jXL0pOL2yTK6r2BxRT_MmCJ4ip4p2-nEEoKnBzASW1kA@mail.gmail.com> <YTXPR01MB0285DC793701FEA545B5E972DDF50@YTXPR01MB0285.CANPRD01.PROD.OUTLOOK.COM>, <CAOtMX2g65aOraEtzM3eU9fqdZ1qtfDbV5YWiZUMvW67O%2BODKJQ@mail.gmail.com>
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Alan Somers wrote: >On Fri, Jul 5, 2019 at 9:11 AM Rick Macklem <rmacklem@uoguelph.ca> wrote: >> >> Alan Somers wrote: >> >On Thu, Jul 4, 2019 at 6:38 PM Rick Macklem <rmacklem@uoguelph.ca> wrot= e: >> >> >> >> I have a little program for testing the copy_file_range(2) syscall I'= ve been >> >> working on. (The current version is attached, in case anyone is inter= ested.) >> >> >> >> It take a few minutes to run on a slow system and uses about 6Gbytes = of disk >> >> space for the file system the output file is on. (It creates 2 files = to use for testing. >> >> The first one is sparse and the second is copied from it, but grows a= s different byte >> >> ranges get copied, since "punching holes" is done via writes of 0 byt= es.) >> >> >> >> My question is.. >> >> What needs to be done to include this in FreeBSD? >> >> I see some stuff under head/tests. I could probably figure out >> >> what the macros in those files are, but I can only see tests to see i= f >> >> arguments are valid and similar. As such, I'm not sure if this is the= correct >> >> place for a test like this? >> >> >> >> Thanks for any help with this, rick >> > >> >head/tests is for complete automated tests, mostly in ATF format. >> >Your program sounds more like the kind of helper program that might be >> >more suitable for head/tools/regression. Those programs all require >> >some operator interaction. If you can automate your program then we >> >should add it to head/tests/sys. Does it really need 6GB to get >> >decent test coverage? >> Well, I wanted the input file to exceed 4Gb and to have a > 4Gb hole in = it, to catch >> 32bit bugs (I test on i386). This did catch some problems during testing= . >> >> Then, the program copies (random) ranges of the file to a second file. I= f the random >> copy is done over the "big hole" for the case where it hasn't truncated = the output >> file (every second iteration), then it writes a "lot of 0s", growing the= output file >> up to 6Gb of data. >> >> I could limit the "random" ranges to not copy the "big hole", but that w= ould avoid >> testing that case. >> >> rick > >random ranges are another problem. Automated tests shouldn't use >random behavior, because then failures won't be reproducible. It's >best to test a set of hand selected edge cases. If you're going to >test random ranges too, then the program should use a user-selectable >random seed (perhaps seeding from the timer if the user doesn't >specify a seed, and printing the seed that was chosen). Good points. Now, I'm about as far from an expert on testing as they come, = but the problem in this case is that I have already written the code to handle = the edge cases I recognized. (Ideally the guy who writes the test program isn't= the guy who wrote the code, but...) By doing the "random" stuff, I am hoping to catch cases that I hadn't antic= ipated. (I put the "random" in quotes, since I use random(3) without seeding it, so= I actually get the same reproducible results.) I crank the # of cycles up so that it runs for hours/days/weeks. I do agree I should add some specific edge cases (which I have already chec= ked) to the test program. rick
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