On Wed, Aug 31, 2022 at 9:52 PM Oscar Salvador <osalvador@xxxxxxx> wrote: > > 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 Hi Oscar, Thanks for the note. I'll take a look most likely on Friday and will follow up with you. Thanks, Suren. > > Thanks > > > -- > Oscar Salvador > SUSE Labs
