On Tue, Aug 30, 2022 at 02:48:49PM -0700, Suren Baghdasaryan wrote: > =========================== > Code tagging framework > =========================== > Code tag is a structure identifying a specific location in the source code > which is generated at compile time and can be embedded in an application- > specific structure. Several applications of code tagging are included in > this RFC, such as memory allocation tracking, dynamic fault injection, > latency tracking and improved error code reporting. > Basically, it takes the old trick of "define a special elf section for > objects of a given type so that we can iterate over them at runtime" and > creates a proper library for it. > > =========================== > Memory allocation tracking > =========================== > The goal for using codetags for memory allocation tracking is to minimize > performance and memory overhead. By recording only the call count and > allocation size, the required operations are kept at the minimum while > collecting statistics for every allocation in the codebase. With that > information, if users are interested in mode detailed context for a > specific allocation, they can enable more in-depth context tracking, > which includes capturing the pid, tgid, task name, allocation size, > timestamp and call stack for every allocation at the specified code > location. > Memory allocation tracking is implemented in two parts: > > part1: instruments page and slab allocators to record call count and total > memory allocated at every allocation in the source code. Every time an > allocation is performed by an instrumented allocator, the codetag at that > location increments its call and size counters. Every time the memory is > freed these counters are decremented. To decrement the counters upon free, > allocated object needs a reference to its codetag. Page allocators use > page_ext to record this reference while slab allocators use memcg_data of > the slab page. > The data is exposed to the user space via a read-only debugfs file called > alloc_tags. Hi Suren, I just posted a patch [1] and reading through your changelog and seeing your PoC, I think we have some kind of overlap. My patchset aims to give you the stacktrace <-> relationship information and it is achieved by a little amount of extra code mostly in page_owner.c/ and lib/stackdepot. Of course, your works seems to be more complete wrt. the information you get. I CCed you in case you want to have a look [1] https://lkml.org/lkml/2022/9/1/36 Thanks -- Oscar Salvador SUSE Labs
