Bug#790571: please give-back capnproto on mipsel

Just noticed that the description in the patch itself misleading --
please disregard that. My earlier email represents my best
understanding of the issue.

On Sat, Aug 1, 2015 at 1:28 PM, Tom Lee <[email protected]> wrote:
> Control: tags -1 +patch
>
> Alrighty, potential patch is attached. Can you folks try it out & let
> me know if it works? If all looks good I'll prep a new upload & send
> the patch upstream.
>
> Dejan, you were right on the money with the page size thing. Looks
> like the write operation in async-unix-test.c++ writes data to the
> pipe until the underlying buffer is completely filled. At that point,
> the write operation fails & the test continues until we hit the read
> operation. At that point we try to read 4096 bytes. It seems like if
> PIPE_BUF > 4096 (where PIPE_BUF is typically the size of a page), the
> pipe doesn't become writable & so the test fails.
>
> I find this behavior a little surprising, but I can reproduce it
> myself on x86_64 by simply changing the buffer size to something less
> than PIPE_BUF. Interesting stuff.
>
> With this patch applied I wouldn't be surprised if we saw the write
> notification fire multiple times (once per PIPE_BUF bytes read). Even
> if that is happening, I feel like we're testing the intended behavior.
>
> Cheers,
> Tom
>
>
> On Sat, Aug 1, 2015 at 9:04 AM, Tom Lee <[email protected]> wrote:
>> Control: tags +confirmed
>>
>> Dejan, Arturo, thanks for looking into this. Sorry I've been so slow
>> to get back to you.
>>
>> Arturo, I understand you've followed up with upstream regarding the
>> affected tests & Kenton's helping you out with some experimental
>> patches to disable the failing tests. I'd be interested to know how
>> that works out, but I do worry that by disabling the tests we'll be
>> potentially glossing over a real issue.
>>
>> Dejan, I think you might be onto something with that 4k buffer but let
>> me look into it a little. Are you aware of any porterboxes with
>> similar setups to mips-aql-02 + mipsel-manda-0{1,2}?
>> https://db.debian.org/machines.cgi?host=eder (Loongson 2E) looks like
>> it might be a promising candidate from a quick google around.
>>
>> I'm guessing this is likely what's causing builds to fail on several
>> other archs too.
>>
>> Cheers,
>> Tom
>>
>> On Fri, Jul 17, 2015 at 8:20 AM, Dejan Latinovic
>> <[email protected]> wrote:
>>>
>>> Hi,
>>> I have tested capnproto on a few local machines.
>>> Initially, build failed on all boards.
>>> On different MIPS boards, different tests were failing.
>>>
>>>
>>> AsyncUnixTest.WriteObserver fails if the kernel PAGESIZE is larger that 4k.
>>>
>>> After I reduced PAGESIZE to 4096 on CI20, all tests passed.
>>>
>>> The solution could be to increase buffer size:
>>>> char buffer[4096]
>>> (src/kj/async-unix-test.c++ +416)
>>> I had increased it to 16384 and tried it on Loongson 3A
>>> (PAGESIZE is 16k, same board as mipsel-manda-01, mipsel-manda-02),
>>> all test passed.
>>> We should keep on mind that pagesize on some MIPS board is up to 64k.
>>> This solution should be discussed upstream.
>>>
>>>
>>> On EdgeRouter Pro (mips-aql-02),
>>> these two test failed:
>>>> [  FAILED  ] 2 tests, listed below:
>>>> [  FAILED  ] AsyncUnixTest.SignalWithValue
>>>> [  FAILED  ] AsyncUnixTest.SignalWithPointerValue
>>>
>>> I will do further investigating.
>>>
>>> Best Regards,
>>> Dejan
>>
>>
>>
>> --
>> Tom Lee / http://tomlee.co / @tglee
>
>
>
> --
> Tom Lee / http://tomlee.co / @tglee



-- 
Tom Lee / http://tomlee.co / @tglee