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From: Suren Baghdasaryan <[email protected]>
To: Marco Elver <[email protected]>
Cc: Michal Hocko <[email protected]>,
	Kent Overstreet <[email protected]>,
	Mel Gorman <[email protected]>,
	Peter Zijlstra <[email protected]>,
	Andrew Morton <[email protected]>,
	Vlastimil Babka <[email protected]>,
	Johannes Weiner <[email protected]>,
	Roman Gushchin <[email protected]>,
	Davidlohr Bueso <[email protected]>,
	Matthew Wilcox <[email protected]>,
	"Liam R. Howlett" <[email protected]>,
	David Vernet <[email protected]>,
	Juri Lelli <[email protected]>,
	Laurent Dufour <[email protected]>,
	Peter Xu <[email protected]>,
	David Hildenbrand <[email protected]>,
	Jens Axboe <[email protected]>,
	[email protected], [email protected], [email protected],
	[email protected], [email protected],
	Vincent Guittot <[email protected]>,
	Dietmar Eggemann <[email protected]>,
	Steven Rostedt <[email protected]>,
	Benjamin Segall <[email protected]>,
	Daniel Bristot de Oliveira <[email protected]>,
	Valentin Schneider <[email protected]>,
	Christopher Lameter <[email protected]>,
	Pekka Enberg <[email protected]>,
	Joonsoo Kim <[email protected]>,
	[email protected], Alexander Potapenko <[email protected]>,
	Dmitry Vyukov <[email protected]>,
	Shakeel Butt <[email protected]>,
	Muchun Song <[email protected]>,
	[email protected], [email protected],
	David Rientjes <[email protected]>,
	Minchan Kim <[email protected]>,
	Kalesh Singh <[email protected]>,
	kernel-team <[email protected]>,
	linux-mm <[email protected]>,
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected],
	LKML <[email protected]>
Subject: Re: [RFC PATCH 00/30] Code tagging framework and applications
Date: Mon, 5 Sep 2022 11:07:25 -0700	[thread overview]
Message-ID: <CAJuCfpF4Meeo5b=ZTGe+YDCd9-jJ+WUazpJzaq7stOu2=1oP9Q@mail.gmail.com> (raw)
In-Reply-To: <CANpmjNOYNWSSiV+VzvzBAeDJX+c1DRP+6jedKMt3gLNg8bgWKA@mail.gmail.com>

On Mon, Sep 5, 2022 at 1:58 AM Marco Elver <[email protected]> wrote:
>
> On Mon, 5 Sept 2022 at 10:12, Michal Hocko <[email protected]> wrote:
> > On Sun 04-09-22 18:32:58, Suren Baghdasaryan wrote:
> > > On Thu, Sep 1, 2022 at 12:15 PM Michal Hocko <[email protected]> wrote:
> > [...]
> > > > Yes, tracking back the call trace would be really needed. The question
> > > > is whether this is really prohibitively expensive. How much overhead are
> > > > we talking about? There is no free lunch here, really.  You either have
> > > > the overhead during runtime when the feature is used or on the source
> > > > code level for all the future development (with a maze of macros and
> > > > wrappers).
> > >
> > > As promised, I profiled a simple code that repeatedly makes 10
> > > allocations/frees in a loop and measured overheads of code tagging,
> > > call stack capturing and tracing+BPF for page and slab allocations.
> > > Summary:
> > >
> > > 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
> >
> > Yes, I am not surprised that the call stack capturing is really
> > expensive comparing to the allocator fast path (which is really highly
> > optimized and I suspect that with 10 allocation/free loop you mostly get
> > your memory from the pcp lists). Is this overhead still _that_ visible
> > for somehow less microoptimized workloads which have to take slow paths
> > as well?
> >
> > Also what kind of stack unwinder is configured (I guess ORC)? This is
> > not my area but from what I remember the unwinder overhead varies
> > between ORC and FP.
> >
> > And just to make it clear. I do realize that an overhead from the stack
> > unwinding is unavoidable. And code tagging would logically have lower
> > overhead as it performs much less work. But the main point is whether
> > our existing stack unwiding approach is really prohibitively expensive
> > to be used for debugging purposes on production systems. I might
> > misremember but I recall people having bigger concerns with page_owner
> > memory footprint than the actual stack unwinder overhead.
>
> This is just to point out that we've also been looking at cheaper
> collection of the stack trace (for KASAN and other sanitizers). The
> cheapest way to unwind the stack would be a system with "shadow call
> stack" enabled. With compiler support it's available on arm64, see
> CONFIG_SHADOW_CALL_STACK. For x86 the hope is that at one point the
> kernel will support CET, which newer Intel and AMD CPUs support.
> Collecting the call stack would then be a simple memcpy.

Thanks for the note Marco! I'll check out the CONFIG_SHADOW_CALL_STACK
on Android.

  reply	other threads:[~2022-09-05 18:07 UTC|newest]

Thread overview: 138+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-30 21:48 [RFC PATCH 00/30] Code tagging framework and applications Suren Baghdasaryan
2022-08-30 21:48 ` [RFC PATCH 01/30] kernel/module: move find_kallsyms_symbol_value declaration Suren Baghdasaryan
2022-08-30 21:48 ` [RFC PATCH 02/30] lib/string_helpers: Drop space in string_get_size's output Suren Baghdasaryan
2022-08-30 21:48 ` [RFC PATCH 03/30] Lazy percpu counters Suren Baghdasaryan
2022-08-31 10:02   ` Mel Gorman
2022-08-31 15:37     ` Suren Baghdasaryan
2022-08-31 16:20     ` Kent Overstreet
2022-09-01  6:51   ` Peter Zijlstra
2022-09-01 14:32     ` Kent Overstreet
2022-09-01 14:48       ` Steven Rostedt
2022-09-01 15:43         ` Kent Overstreet
2022-09-01 18:59       ` Peter Zijlstra
2022-08-30 21:48 ` [RFC PATCH 04/30] scripts/kallysms: Always include __start and __stop symbols Suren Baghdasaryan
2022-08-30 21:48 ` [RFC PATCH 05/30] lib: code tagging framework Suren Baghdasaryan
2022-08-30 21:48 ` [RFC PATCH 06/30] lib: code tagging module support Suren Baghdasaryan
2022-08-30 21:48 ` [RFC PATCH 07/30] lib: add support for allocation tagging Suren Baghdasaryan
2022-08-30 21:48 ` [RFC PATCH 08/30] lib: introduce page " Suren Baghdasaryan
2022-08-30 21:48 ` [RFC PATCH 09/30] change alloc_pages name in dma_map_ops to avoid name conflicts Suren Baghdasaryan
2022-08-30 21:48 ` [RFC PATCH 10/30] mm: enable page allocation tagging for __get_free_pages and alloc_pages Suren Baghdasaryan
2022-08-31 10:11   ` Mel Gorman
2022-08-31 15:45     ` Suren Baghdasaryan
2022-08-31 15:52       ` Suren Baghdasaryan
2022-08-31 17:46     ` Kent Overstreet
2022-09-01  1:07       ` Suren Baghdasaryan
2022-09-01  7:41       ` Peter Zijlstra
2022-08-30 21:49 ` [RFC PATCH 11/30] mm: introduce slabobj_ext to support slab object extensions Suren Baghdasaryan
2022-09-01 23:35   ` Roman Gushchin
2022-09-02  0:23     ` Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 12/30] mm: introduce __GFP_NO_OBJ_EXT flag to selectively prevent slabobj_ext creation Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 13/30] mm/slab: introduce SLAB_NO_OBJ_EXT to avoid obj_ext creation Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 14/30] mm: prevent slabobj_ext allocations for slabobj_ext and kmem_cache objects Suren Baghdasaryan
2022-09-01 23:40   ` Roman Gushchin
2022-09-02  0:24     ` Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 15/30] lib: introduce slab allocation tagging Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 16/30] mm: enable slab allocation tagging for kmalloc and friends Suren Baghdasaryan
2022-09-01 23:50   ` Roman Gushchin
2022-08-30 21:49 ` [RFC PATCH 17/30] lib/string.c: strsep_no_empty() Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 18/30] codetag: add codetag query helper functions Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 19/30] move stack capture functionality into a separate function for reuse Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 20/30] lib: introduce support for storing code tag context Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 21/30] lib: implement context capture support for page and slab allocators Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 22/30] Code tagging based fault injection Suren Baghdasaryan
2022-08-31  1:51   ` Randy Dunlap
2022-08-31 15:56     ` Suren Baghdasaryan
2022-08-31 10:37   ` Dmitry Vyukov
2022-08-31 15:51     ` Suren Baghdasaryan
2022-08-31 17:30     ` Kent Overstreet
2022-09-01  8:43       ` Dmitry Vyukov
2022-08-30 21:49 ` [RFC PATCH 23/30] timekeeping: Add a missing include Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 24/30] wait: Clean up waitqueue_entry initialization Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 25/30] lib/time_stats: New library for statistics on events Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 26/30] bcache: Convert to lib/time_stats Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 27/30] Code tagging based latency tracking Suren Baghdasaryan
2022-08-31  1:53   ` Randy Dunlap
2022-08-31 15:55     ` Suren Baghdasaryan
2022-09-01  7:11   ` Peter Zijlstra
2022-09-01 14:43     ` Kent Overstreet
2022-09-01 21:38   ` Steven Rostedt
2022-09-01 21:46     ` Steven Rostedt
2022-09-01 21:54     ` Kent Overstreet
2022-09-01 22:34       ` Steven Rostedt
2022-09-01 22:55         ` Kent Overstreet
2022-09-02  0:23           ` Steven Rostedt
2022-09-02  1:35             ` Kent Overstreet
2022-09-02  1:59               ` Steven Rostedt
2022-08-30 21:49 ` [RFC PATCH 28/30] Improved symbolic error names Suren Baghdasaryan
2022-09-01 23:19   ` Joe Perches
2022-09-01 23:26     ` Kent Overstreet
2022-08-30 21:49 ` [RFC PATCH 29/30] dyndbg: Convert to code tagging Suren Baghdasaryan
2022-08-30 21:49 ` [RFC PATCH 30/30] MAINTAINERS: Add entries for code tagging & related Suren Baghdasaryan
2022-08-31  7:38 ` [RFC PATCH 00/30] Code tagging framework and applications Peter Zijlstra
2022-08-31  8:42   ` Kent Overstreet
2022-08-31 10:19     ` Mel Gorman
2022-08-31 10:47       ` Michal Hocko
2022-08-31 15:28         ` Suren Baghdasaryan
2022-08-31 16:48           ` Suren Baghdasaryan
2022-08-31 19:01         ` Kent Overstreet
2022-08-31 20:56           ` Yosry Ahmed
2022-08-31 21:38             ` Suren Baghdasaryan
2022-09-01 22:27             ` Roman Gushchin
2022-09-01 22:37               ` Kent Overstreet
2022-09-01 22:53                 ` Roman Gushchin
2022-09-01 23:36                   ` Suren Baghdasaryan
2022-09-02  0:17                   ` Kent Overstreet
2022-09-02  1:04                     ` Roman Gushchin
2022-09-02  1:16                       ` Kent Overstreet
2022-09-02 12:02                       ` Jens Axboe
2022-09-02 19:48                         ` Kent Overstreet
2022-09-02 19:53                           ` Jens Axboe
2022-09-02 20:05                             ` Kent Overstreet
2022-09-02 20:23                               ` Jens Axboe
2022-09-01  7:18           ` Michal Hocko
2022-09-01 15:33             ` Suren Baghdasaryan
2022-09-01 19:15               ` Michal Hocko
2022-09-01 19:39                 ` Suren Baghdasaryan
2022-09-01 20:15                   ` Kent Overstreet
2022-09-05  8:49                     ` Michal Hocko
2022-09-05 23:46                       ` Kent Overstreet
2022-09-06  7:23                         ` Michal Hocko
2022-09-06 18:20                           ` Kent Overstreet
2022-09-07 11:00                             ` Michal Hocko
2022-09-07 13:04                               ` Kent Overstreet
2022-09-07 13:45                                 ` Steven Rostedt
2022-09-08  6:35                                   ` Kent Overstreet
2022-09-08  6:49                                     ` Suren Baghdasaryan
2022-09-08  7:07                                       ` Kent Overstreet
2022-09-08  7:12                                     ` Michal Hocko
2022-09-08  7:29                                       ` Kent Overstreet
2022-09-08  7:47                                         ` Michal Hocko
2022-09-05  1:32                 ` Suren Baghdasaryan
2022-09-05  8:12                   ` Michal Hocko
2022-09-05  8:58                     ` Marco Elver
2022-09-05 18:07                       ` Suren Baghdasaryan [this message]
2022-09-05 18:03                     ` Suren Baghdasaryan
2022-09-06  8:01                       ` Michal Hocko
2022-09-06 15:35                         ` Suren Baghdasaryan
2022-09-05 15:07                   ` Steven Rostedt
2022-09-05 18:08                     ` Suren Baghdasaryan
2022-09-05 20:42                       ` Kent Overstreet
2022-09-05 22:16                         ` Steven Rostedt
2022-09-05 23:50                           ` Kent Overstreet
2022-09-01  8:05           ` David Hildenbrand
2022-09-01 14:23             ` Kent Overstreet
2022-09-01 15:07               ` David Hildenbrand
2022-09-01 15:39                 ` Suren Baghdasaryan
2022-09-01 15:48                 ` Kent Overstreet
2022-08-31 15:59       ` Kent Overstreet
2022-09-01  7:05         ` Peter Zijlstra
2022-09-01  7:36           ` Daniel Bristot de Oliveira
2022-09-01  7:42           ` Peter Zijlstra
2022-09-01 11:05         ` Mel Gorman
2022-09-01 16:31           ` Kent Overstreet
2022-09-01  7:00       ` Peter Zijlstra
2022-09-01 14:29         ` Kent Overstreet
2022-09-05 18:44       ` Nadav Amit
2022-09-05 19:16         ` Steven Rostedt
2022-09-01  4:52 ` Oscar Salvador
2022-09-01  5:05   ` Suren Baghdasaryan

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