4 ms·
I saw a youtube talk on this one ... I think it was this one: https://www.youtube.com/watch?v=O1YP8QP9gLA https://www.youtube.com/watch?v=O1YP8QP9gLA Really gr
by alexc05 11y ago
I saw a youtube talk on this one ... I think it was this one: https://www.youtube.com/watch?v=O1YP8QP9gLA https://www.youtube.com/watch?v=O1YP8QP9gLA
Really great stuff. The spot where he gets to a pretty good description of how he uses his flame graph is roughly here: https://youtu.be/O1YP8QP9gLA?t=611 https://youtu.be/O1YP8QP9gLA?t=611
With respect to that blog-post the bit about the truncated towers is a bit of a red herring if you're 100% new to flame graphs.
The real meaty bits are the wide sections.
- MikeTheJoker 11y agoGenerally you're right that the wide sections are where you want to focus your attention when looking for optimizations. The point I was trying to make in the blog post is that we had to take the flame graph visualization a step further to eliminate the noise obscuring a major hot spot. The large number of broken stacks was one of the first hurdles we had to cross to improve the clarity of the visualization. BTW, this is a different flame graph and optimization than the one discussed in the YouTube video. We use flame graphs extensively throughout Netflix.
- m4dc4pXXX 11y agoCan you write up how you fixed the broken call stacks? I've used Brendan's tools (with java-perf-map, also an awesome tool) to generate flame graphs for Scala code and had no idea I could only see 127 frames.
- brendangregg 11y agoWe ultimately should be fixing this with BPF, which we'll certainly post instructions for.