On Thu, Oct 17, 2019 at 11:23:20AM -0700, Steve MacLean wrote: > From: Steve MacLean <steve.macl...@microsoft.com> > > 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 colocated 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 file represents inferior information which has been superceded by the 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 sucessfully injected a jitdump file. > > During "perf inject --jit", discard "//anon*" mmap events for any pid which > has sucessfully 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 posted some questions for previous version in here, but can't find answers: https://lore.kernel.org/lkml/20191003105716.GB23291@krava/ thanks, jirka
