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Wed, 17 Jan 2024 15:02:46 -0800 (PST) MIME-Version: 1.0 References: <20240115092727.888096-1-elver@google.com> In-Reply-To: <20240115092727.888096-1-elver@google.com> From: Andrey Konovalov Date: Thu, 18 Jan 2024 00:02:35 +0100 Message-ID: Subject: Re: [PATCH RFC 1/2] stackdepot: add stats counters exported via debugfs To: Marco Elver Cc: Andrew Morton , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 895141C001F X-Stat-Signature: gurfgt3j1x7htqkyqw64fj3jcz1rtnmp X-Rspam-User: X-HE-Tag: 1705532568-858101 X-HE-Meta: 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 ZNV03jcp v5KcBdJ7ulJ8/BeZU6vOk8LrNUy/5WcHqiR93Mh4kfitYL98FyNcpYwfgS3EZB7KGMtsmda3jEkTDVimhGCv6hMUyynv5Bo+3uneTap906+wXbh+0eGGByORK07w7eYIl9XhDfBju9odawqYO1LKTmS+1/U8sdOylfiTZALIBmbftSi+iDWua0sd+HauXgpJG1U69GLXKsXgD2bSAgFQDFAdZS/u2GnHGTA4GBhVUT/08MG3hH0OVGyk1jLQ9UEdaygkXdCoSRiG+3k+oKPBS0nIm3+DM0rptLuy+oMOpWXKmcCS2NpLIEg9p8zDeeq31826Ep/xubOm7iEXH4RWDgnJU5CclfbaZb4a8q1kx83/s1qMvwHGJCv3AJLUvN4GjzLKQ6Esz3EsZ1bQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jan 15, 2024 at 10:27=E2=80=AFAM Marco Elver wro= te: > > Add a few basic stats counters for stack depot that can be used to derive= if > stack depot is working as intended. This is a snapshot of the new stats a= fter > booting a system with a KASAN-enabled kernel: > > $ cat /sys/kernel/debug/stackdepot/stats > pools: 838 > allocations: 29861 > frees: 6561 > in_use: 23300 > freelist_size: 1840 > > Generally, "pools" should be well below the max; once the system is boote= d, > "in_use" should remain relatively steady. > > Signed-off-by: Marco Elver > --- > lib/stackdepot.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 53 insertions(+) > > diff --git a/lib/stackdepot.c b/lib/stackdepot.c > index a0be5d05c7f0..80a8ca24ccc8 100644 > --- a/lib/stackdepot.c > +++ b/lib/stackdepot.c > @@ -14,6 +14,7 @@ > > #define pr_fmt(fmt) "stackdepot: " fmt > > +#include > #include > #include > #include > @@ -115,6 +116,23 @@ static bool new_pool_required =3D true; > /* Lock that protects the variables above. */ > static DEFINE_RWLOCK(pool_rwlock); > > +/* Statistics counters for debugfs. */ > +enum depot_counter_id { > + DEPOT_COUNTER_ALLOCS, > + DEPOT_COUNTER_FREES, > + DEPOT_COUNTER_INUSE, > + DEPOT_COUNTER_FREELIST_SIZE, > + DEPOT_COUNTER_COUNT, > +}; > +static long counters[DEPOT_COUNTER_COUNT]; > +static const char *const counter_names[] =3D { > + [DEPOT_COUNTER_ALLOCS] =3D "allocations", > + [DEPOT_COUNTER_FREES] =3D "frees", > + [DEPOT_COUNTER_INUSE] =3D "in_use", > + [DEPOT_COUNTER_FREELIST_SIZE] =3D "freelist_size", > +}; > +static_assert(ARRAY_SIZE(counter_names) =3D=3D DEPOT_COUNTER_COUNT); > + > static int __init disable_stack_depot(char *str) > { > return kstrtobool(str, &stack_depot_disabled); > @@ -277,6 +295,7 @@ static void depot_init_pool(void *pool) > stack->handle.extra =3D 0; > > list_add(&stack->list, &free_stacks); > + counters[DEPOT_COUNTER_FREELIST_SIZE]++; > } > > /* Save reference to the pool to be used by depot_fetch_stack(). = */ > @@ -376,6 +395,7 @@ depot_alloc_stack(unsigned long *entries, int size, u= 32 hash, void **prealloc) > /* Get and unlink the first entry from the freelist. */ > stack =3D list_first_entry(&free_stacks, struct stack_record, lis= t); > list_del(&stack->list); > + counters[DEPOT_COUNTER_FREELIST_SIZE]--; > > /* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. = */ > if (size > CONFIG_STACKDEPOT_MAX_FRAMES) > @@ -394,6 +414,8 @@ depot_alloc_stack(unsigned long *entries, int size, u= 32 hash, void **prealloc) > */ > kmsan_unpoison_memory(stack, DEPOT_STACK_RECORD_SIZE); > > + counters[DEPOT_COUNTER_ALLOCS]++; > + counters[DEPOT_COUNTER_INUSE]++; > return stack; > } > > @@ -426,6 +448,10 @@ static void depot_free_stack(struct stack_record *st= ack) > lockdep_assert_held_write(&pool_rwlock); > > list_add(&stack->list, &free_stacks); > + > + counters[DEPOT_COUNTER_FREELIST_SIZE]++; > + counters[DEPOT_COUNTER_FREES]++; > + counters[DEPOT_COUNTER_INUSE]--; > } > > /* Calculates the hash for a stack. */ > @@ -690,3 +716,30 @@ unsigned int stack_depot_get_extra_bits(depot_stack_= handle_t handle) > return parts.extra; > } > EXPORT_SYMBOL(stack_depot_get_extra_bits); > + > +static int stats_show(struct seq_file *seq, void *v) > +{ > + /* > + * data race ok: These are just statistics counters, and approxim= ate > + * statistics are ok for debugging. > + */ > + seq_printf(seq, "pools: %d\n", data_race(pools_num)); > + for (int i =3D 0; i < DEPOT_COUNTER_COUNT; i++) > + seq_printf(seq, "%s: %ld\n", counter_names[i], data_race(= counters[i])); > + > + return 0; > +} > +DEFINE_SHOW_ATTRIBUTE(stats); > + > +static int depot_debugfs_init(void) > +{ > + struct dentry *dir; > + > + if (stack_depot_disabled) > + return 0; > + > + dir =3D debugfs_create_dir("stackdepot", NULL); > + debugfs_create_file("stats", 0444, dir, NULL, &stats_fops); > + return 0; > +} > +late_initcall(depot_debugfs_init); > -- > 2.43.0.275.g3460e3d667-goog > Reviewed-by: Andrey Konovalov