Re: [Tarantool-patches] [PATCH luajit v4 3/4] memprof: group allocations on traces by traceno

[Igor Munkin via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Misha,

Thanks for the fixes! LGTM now.

On 04.11.21, Mikhail Shishatskiy wrote:
> Hi, Igor!
> Thank you for the review!
> 
> New commit message:
> ============================================================
> memprof: group allocations on traces by traceno
> 
> When LuaJIT executes a trace, the trace number is stored as
> the virtual machine state. So, we can treat this number as
> an allocation event source in memprof and report allocation events
> from traces as well.
> 
> Previously, all the allocations from traces were marked as INTERNAL.
> 
> This patch introduces the functionality described above by adding
> a new allocation source type named ASOURCE_TRACE. If allocation event
> occurs when trace is executed, trace number and trace's mcode starting
> address are streamed to a binary file:
> 
> | loc-trace  := trace-no trace-addr
> | trace-no   := <ULEB128>
> | trace-addr := <ULEB128>
> 
> Also, the memory profiler parser is adjusted to recognize entries
> mentioned above. The <loc> structure is extended with field <traceno>,
> representing trace number. Trace locations are demangled as
> 
> | TRACE [<trace-no>] <trace-addr>
> 
> Resolves tarantool/tarantool#5814
> ============================================================
> 
> Diff:
> ============================================================
> diff --git a/test/tarantool-tests/misclib-memprof-lapi.test.lua b/test/tarantool-tests/misclib-memprof-lapi.test.lua
> index 0328c06d..4b7140e9 100644
> --- a/test/tarantool-tests/misclib-memprof-lapi.test.lua
> +++ b/test/tarantool-tests/misclib-memprof-lapi.test.lua
> @@ -113,14 +113,15 @@ local function form_source_line(line)
>     return string.format("@%s:%d", arg[0], line)
>   end
> 
> -local function check_alloc_report(alloc, traceno, line, function_line, nevents)
> +local function check_alloc_report(alloc, location, nevents)
>     local expected_name, event
> -  if traceno ~= 0 then
> +  local traceno = location.traceno
> +  if traceno then
>       expected_name = string.format("TRACE [%d]", traceno)
>       event = alloc.trace[traceno]
>     else
> -    expected_name = form_source_line(function_line)
> -    event = alloc.line[line]
> +    expected_name = form_source_line(location.linedefined)
> +    event = alloc.line[location.line]
>     end
>     assert(expected_name == event.name, ("got='%s', expected='%s'"):format(
>       event.name,
> @@ -173,9 +174,9 @@ test:test("output", function(subtest)
>     -- one is the number of allocations. 1 event - alocation of
>     -- table by itself + 1 allocation of array part as far it is
>     -- bigger than LJ_MAX_COLOSIZE (16).
> -  subtest:ok(check_alloc_report(alloc, 0, 34, 32, 2))
> +  subtest:ok(check_alloc_report(alloc, { line = 34, linedefined = 32 }, 2))
>     -- 20 strings allocations.
> -  subtest:ok(check_alloc_report(alloc, 0, 39, 32, 20))
> +  subtest:ok(check_alloc_report(alloc, { line = 39, linedefined = 32 }, 20))
> 
>     -- Collect all previous allocated objects.
>     subtest:ok(free.INTERNAL.num == 22)
> @@ -238,9 +239,9 @@ test:test("jit-output", function(subtest)
>     local free = fill_ev_type(events, symbols, "free")
> 
>     -- We expect, that loop will be compiled into a trace.
> -  subtest:ok(check_alloc_report(alloc, 1, 37, 32, 20))
> +  subtest:ok(check_alloc_report(alloc, { traceno = 1 }, 20))
>     -- See same checks with jit.off().
> -  subtest:ok(check_alloc_report(alloc, 0, 34, 32, 2))
> +  subtest:ok(check_alloc_report(alloc, { line = 34, linedefined = 32 }, 2))
>     subtest:ok(free.INTERNAL.num == 22)
> 
>     -- Restore default JIT settings.
> diff --git a/tools/utils/symtab.lua b/tools/utils/symtab.lua
> index 85945fb2..c4acc4cb 100644
> --- a/tools/utils/symtab.lua
> +++ b/tools/utils/symtab.lua
> @@ -77,26 +77,22 @@ function M.id(loc)
>     return string_format("f%#xl%dt%d", loc.addr, loc.line, loc.traceno)
>   end
> 
> -local function demangle_lfunc(symtab, loc)
> +function M.demangle(symtab, loc)
> +  if loc.traceno ~= 0 then
> +    return string_format("TRACE [%d] %#x", loc.traceno, loc.addr)
> +  end
> +
>     local addr = loc.addr
> 
>     if addr == 0 then
>       return "INTERNAL"
> -  elseif symtab[addr] then
> -    return string_format("%s:%d", symtab[addr].source, loc.line)
>     end
> -  return string_format("CFUNC %#x", addr)
> -end
> 
> -local function demangle_trace(loc)
> -  return string_format("TRACE [%d] %#x", loc.traceno, loc.addr)
> -end
> -
> -function M.demangle(symtab, loc)
> -  if loc.traceno ~= 0 then
> -    return demangle_trace(loc)
> +  if symtab[addr] then
> +    return string_format("%s:%d", symtab[addr].source, loc.line)
>     end
> -  return demangle_lfunc(symtab, loc)
> +
> +  return string_format("CFUNC %#x", addr)
>   end
> 
>   return M
> ============================================================
> 
> Issue: https://github.com/tarantool/tarantool/issues/5814
> Branch: https://github.com/tarantool/luajit/tree/shishqa/gh-5814-group-allocations-on-trace-by-trace-number
> CI: https://github.com/tarantool/tarantool/tree/shishqa/gh-5814-group-allocations-on-trace-by-trace-number
> 
> On 27.10.2021 16:56, Igor Munkin wrote:
> >Misha,
> >
> >Thanks for the patch! Please, consider the comments below.
> >
> >On 29.09.21, Mikhail Shishatskiy wrote:

<snipped>

> 
> >
> >Typo: s/streamed/is streamed/.
> 
> I assume, there should be s/streamed/are streamed/.

Precisely.

> 

<snipped>

> >>
> >> Resolves tarantool/tarantool#5814
> >
> >Does this patch "resolve" the issue or only being a "part of" it?
> 
> IMO, this patch _resolves_ the issue, as we are now able to get
> information about allocations on particular traces:
> 
> | TRACE [<trace-no>] <trace-addr>
> 
> And this is exactly what was requested in the issue.

Got it, thanks.

> 

<snipped>

> >
> >-- 
> >Best regards,
> >IM
> 
> --
> Best regards,
> Mikhail Shishatskiy

-- 
Best regards,
IM