Re: [Tarantool-patches] [PATCH luajit v1] memprof: report all JIT-related allocations as internal

[Mikhail Shishatskiy via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

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Hi, Sergey!
Thank you for the review! I will fix the nitpicks in the next version
of the patch.
  
>Вторник, 27 июля 2021, 17:00 +03:00 от Sergey Kaplun <skaplun@tarantool.org>:
> 
>Hi, Mikhail!
>
>Thanks for the patch!
>
>On 22.07.21, Mikhail Shishatskiy wrote:
>
>| memprof: report all JIT-related allocations as internal
>
>Width limit for commit title is 50 symbols including subsystem name
>considering our code style guide [1].
>
>> There are cases when the memory profiler attempts to attribute
>> allocations triggered by the JIT engine recording phase
>> with a Lua function to be recorded. In this case,
>> lj_debug_frameline() may return BC_NOPOS (i.e. a negative value).
>>
>> Previously, these situations were ignored and the profiler
>> reported, that the source line was equal to zero.
>>
>> This patch adjusts profiler behavior to treat allocations
>> described above as internal by dumping ASOURCE_INT if
>> lj_debug_frameline() returns a negative value.
>
>Maybe it is better to catch out the JIT-related allocation and associate
>it with the corresponding trace after these issues [2][3] will be
>resolved, isn't it?
>Otherwise after fixing other nitpicks patch LGTM.
>
>Thoughts?
 
I’ve tested the behavior of such allocations: all of them are actually connected to
the growth of general-purpose vectors in the JIT state. It is a controversial question,
should we report them as trace-related or as internal. IMO, internal is better, as
we do not confuse users by mixing the number of internally allocated bytes with bytes
allocated from the actual payload.
 
>>
>> Resolves tarantool/tarantool#5679
>> ---
>>
>> Issue:  https://github.com/tarantool/tarantool/issues/5679
>> Branch:  https://github.com/tarantool/luajit/tree/shishqa/gh-5679-report-jit-allocations-as-internal
>
>Sorry, I can't find Tarantool's standalone branch with these changes to
>check CI. May you please share it here?
 
Strange, I can not find it too, but remember that I have pushed it. I think
I can rebase to the branch [1], as the current patch uses the same changes
in the memprof tests. And when [1] will be approved, I will resend the new 
version with a shorter commit message title and some changes in tests (see below).
 
>>
>> src/lj_memprof.c | 28 +++++++----
>> .../misclib-memprof-lapi.test.lua | 50 ++++++++++++-------
>> 2 files changed, 51 insertions(+), 27 deletions(-)
>>
>> diff --git a/src/lj_memprof.c b/src/lj_memprof.c
>> index 2c1ef3b8..b4985b8e 100644
>> --- a/src/lj_memprof.c
>> +++ b/src/lj_memprof.c
<snipped>
>>
>> +-- Test for marking jit-related allocations as internal.
>> +-- See also  https://github.com/tarantool/tarantool/issues/5679 .
>> jit.on()
>> +symbols, events = generate_parsed_output(TMP_BINFILE, function()
>
>Why do you use this instead of default_payload?
>Please drop a comment here.
 
I’ve checked again and realized, that I can use default_payload to test this behavior :)
 
>> + for _ = 1, 100 do
>> + local _ = {_, _}
>> + end
>> +end)
>> +alloc = fill_ev_type(events, symbols, "alloc")
>> +test:ok(alloc[0] == nil)
>> +
>> os.exit(test:check() and 0 or 1)
>> --
>> 2.32.0
>>
>
>[1]:  https://github.com/tarantool/tarantool/wiki/Code-review-procedure#commit-message
>[2]:  https://github.com/tarantool/tarantool/issues/5814
>[3]:  https://github.com/tarantool/tarantool/issues/5815
>
>--
>Best regards,
>Sergey Kaplun
 
[1]: https://github.com/tarantool/luajit/tree/shishqa/gh-5814-group-allocations-on-trace-by-trace-number
--
Best regards,
Mikhail Shishatskiy

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