Re: [PATCH 3/4] perf inject --jit: Remove //anon mmap events

Jiri Olsa
2019-09-29T15:30:06Z

On Sat, Sep 28, 2019 at 01:45:36AM +0000, Steve MacLean wrote:
> While a JIT is jitting code it will eventually need to commit more pages and
> change these pages to executable permissions.
>
> Typically the JIT will want these co-located to minimize branch displacements.
>
> The kernel will coalesce these anonymous mapping with identical permissions
> before sending an mmap event for the new pages. This means the mmap event for
> the new pages will include the older pages.
>
> These anonymous mmap events will obscure the jitdump injected pseudo events.
> This means that the jitdump generated symbols, machine code, debugging info,
> and unwind info will no longer be used.
>
> Observations:
>
> When a process emits a jit dump marker and a jitdump file, the perf-xxx.map
> file represents inferior information which has been superseded by the
> jitdump jit-xxx.dump file.
>
> Further the '//anon*' mmap events are only required for the legacy
> perf-xxx.map mapping.
>
> Summary:
>
> Add rbtree to track which pids have successfully injected a jitdump file.
>
> During "perf inject --jit", discard "//anon*" mmap events for any pid which
> has successfully processed a jitdump file.
>
> Committer testing:
>
> // jitdump case
> perf record <app with jitdump>
> perf inject --jit --input perf.data --output perfjit.data
>
> // verify mmap "//anon" events present initially
> perf script --input perf.data --show-mmap-events | grep '//anon'
> // verify mmap "//anon" events removed
> perf script --input perfjit.data --show-mmap-events | grep '//anon'
>
> // no jitdump case
> perf record <app without jitdump>
> perf inject --jit --input perf.data --output perfjit.data
>
> // verify mmap "//anon" events present initially
> perf script --input perf.data --show-mmap-events | grep '//anon'
> // verify mmap "//anon" events not removed
> perf script --input perfjit.data --show-mmap-events | grep '//anon'
>
> Repro:
>
> This issue was discovered while testing the initial CoreCLR jitdump
> implementation. https://github.com/dotnet/coreclr/pull/26897.

I can't apply this one:

patching file builtin-inject.c
Hunk #1 FAILED at 263.
1 out of 1 hunk FAILED -- saving rejects to file builtin-inject.c.rej
patching file util/jitdump.c
patch: **** malformed patch at line 236: btree, node);

jirka