Re: [RFC PATCH 00/30] Code tagging framework and applications

Steven Rostedt
2022-09-05T15:06:50Z

On Sun, 4 Sep 2022 18:32:58 -0700
Suren Baghdasaryan <surenb@google.com> wrote:

> Page allocations (overheads are compared to get_free_pages() duration):
> 6.8% Codetag counter manipulations (__lazy_percpu_counter_add + __alloc_tag_add)
> 8.8% lookup_page_ext
> 1237% call stack capture
> 139% tracepoint with attached empty BPF program

Have you tried tracepoint with custom callback?

static void my_callback(void *data, unsigned long call_site,
const void *ptr, struct kmem_cache *s,
size_t bytes_req, size_t bytes_alloc,
gfp_t gfp_flags)
{
struct my_data_struct *my_data = data;

{ do whatever }
}

[..]
register_trace_kmem_alloc(my_callback, my_data);

Now the my_callback function will be called directly every time the
kmem_alloc tracepoint is hit.

This avoids that perf and BPF overhead.

-- Steve