Linking call stack to timeline

[aulwes]

Hi, In the latest master branch, the struct SegmentInfo contains the field, allocTime, which implies the time when an allocation occurs. How can I get this info from the json output file from a call stack? What I'm attempting to do is link a call stack to a particular time in the Timeline view. For example, if I see a large jump in physical memory, I'd like to determine which allocation caused the jump. it seems there must be some way for me to parse the json output to read the allocTime and find the associated call stack.

[svalat]

Hi,
thanks for the question.
The allocTime is there since the origin of MALT to compute the lifetime of the segment. It is used only at free time to calculate the lifetime.
In practice, last year I reworked the tracing mechanism of MALT backend so you can get the full trace of allocs.
If I rewrite the web interface, this because I want to offer this trace base analysis in an optional second step which was hard to do in the old one.

I don't yet make those info poping up in the interface but I will do as soon a I found time. I want to have to feature : being able to see what you ask, what allocations are in a specific region. And get the time details in the source annotation with a time chart per location.

If ever you want to explore on your side, you can malt -o trace:enabled=true ......, you will get a trace file with the stack info attached to each alloc.

Otherwise by writing this response, I'm thinking we can still do it in a profile base way not to down to the trace. (so thanks for the question).

I need to

• Trick the MALT::ProfiledValue class so we can use as the template a list of stacks concerned.
• When getting an alloc, register it to this list in the current frame.

I will be relatively "easy" to make a new page with a chart and print on each point the list of stacks concerned.

Do you want to try, or do you want I give a look (I'm not sure to have time in the coming 4 weeks).

[aulwes]

I will try the trace:enabled=true option. I'm sure if I try to do the modifications, it will take me much longer, so will leave it to you. Thank you!

[aulwes]

What tool do I use to parse or view the .trace file?

[svalat]

OK, with the trace you will for now have the info about virtual memory, not the physical one. I still miss one feature I want to implement for this.

For the trace, there is a reader but not exposed outside, I'm preparing a patch for end next week so you can play with that on your side via a C API, it is mostly ready.

It is also usefull to me to inject the info in the WebUI.

[aulwes]

ok, thank you, I'll look for the reader next week.