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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1724522705; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=b1cr4HFsHjQtQrwgw0v0pluuE8by2jRYsZZv2/hFaZA=; b=ZjuVLsG2af5BTL4yTIoOCaNYOnmQsVvqocvTVD8x5DMshfnenznngvORvY0M2a/LPdMelH j84ABf3my8Usx7Mih1zSSJodMHSVl255PRv3tceacTMhKb7nGd0p4VtNsTjD5GdvmVMhYo IYB1NomBNdGKl2rJYJJVuPS61jXjwfk= From: Kent Overstreet To: david@fromorbit.com, linux-fsdevel@vger.kernel.org, linux-mm@vger.kernel.org Cc: Kent Overstreet , Andrew Morton , Qi Zheng , Roman Gushchin , linux-mm@kvack.org Subject: [PATCH 03/10] mm: shrinker: Add new stats for .to_text() Date: Sat, 24 Aug 2024 14:04:45 -0400 Message-ID: <20240824180454.3160385-4-kent.overstreet@linux.dev> In-Reply-To: <20240824180454.3160385-1-kent.overstreet@linux.dev> References: <20240824180454.3160385-1-kent.overstreet@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 23A3E12000A X-Stat-Signature: 8wd8pbtabagikfs3pbpazwbhbgribi4s X-Rspam-User: X-HE-Tag: 1724522706-707435 X-HE-Meta: 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 Cy+pqLut wW7DQnDb8QRTildxe1mx3C8Gd/3jiHwizsgSOUnw+rZgozm+ZMGS0Gx9E9vSpojv2BOCqC+eU1lE4N2vyFw5Xvw+SF2Ft1+hug5oKCnBCzQLADuPRBFwtCJHRnCfpTwyQPsdpfBMIsfo78Hg934BkLb9oi4I9xYfbkHHqbyaIyNlHvMMmkT3rZMPWfWI/bNAuYjAzvn1pbvWvaz8H4/4ofyNCHnrEpICY50ste/X6XMQdGbLfrYU7366UCyaeFnwh6BkHx7LxcFALPmB4Zd2YLLXM/MdWpITofTN34cVj9T0KskzorgDqUipvIYbMJtrMGM0IfDRuXcy9n7oJMKPHCe9o/Q== 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: Add a few new shrinker stats. number of objects requested to free, number of objects freed: Shrinkers won't necessarily free all objects requested for a variety of reasons, but if the two counts are wildly different something is likely amiss. .scan_objects runtime: If one shrinker is taking an excessive amount of time to free objects that will block kswapd from running other shrinkers. Cc: Andrew Morton Cc: Qi Zheng Cc: Roman Gushchin Cc: linux-mm@kvack.org Signed-off-by: Kent Overstreet --- include/linux/shrinker.h | 6 ++++++ mm/shrinker.c | 23 ++++++++++++++++++++++- 2 files changed, 28 insertions(+), 1 deletion(-) diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 6193612617a1..106622ddac77 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -118,6 +118,12 @@ struct shrinker { #endif /* objs pending delete, per node */ atomic_long_t *nr_deferred; + + atomic_long_t objects_requested_to_free; + atomic_long_t objects_freed; + unsigned long last_freed; /* timestamp, in jiffies */ + unsigned long last_scanned; /* timestamp, in jiffies */ + atomic64_t ns_run; }; #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ diff --git a/mm/shrinker.c b/mm/shrinker.c index ad52c269bb48..feaa8122afc9 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -430,13 +430,24 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, total_scan >= freeable) { unsigned long ret; unsigned long nr_to_scan = min(batch_size, total_scan); + u64 start_time = ktime_get_ns(); + + atomic_long_add(nr_to_scan, &shrinker->objects_requested_to_free); shrinkctl->nr_to_scan = nr_to_scan; shrinkctl->nr_scanned = nr_to_scan; ret = shrinker->scan_objects(shrinker, shrinkctl); + + atomic64_add(ktime_get_ns() - start_time, &shrinker->ns_run); if (ret == SHRINK_STOP) break; freed += ret; + unsigned long now = jiffies; + if (ret) { + atomic_long_add(ret, &shrinker->objects_freed); + shrinker->last_freed = now; + } + shrinker->last_scanned = now; count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); total_scan -= shrinkctl->nr_scanned; @@ -812,9 +823,19 @@ EXPORT_SYMBOL_GPL(shrinker_free); void shrinker_to_text(struct seq_buf *out, struct shrinker *shrinker) { struct shrink_control sc = { .gfp_mask = GFP_KERNEL, }; + unsigned long nr_freed = atomic_long_read(&shrinker->objects_freed); seq_buf_puts(out, shrinker->name); - seq_buf_printf(out, " objects: %lu\n", shrinker->count_objects(shrinker, &sc)); + seq_buf_putc(out, '\n'); + + seq_buf_printf(out, "objects: %lu\n", shrinker->count_objects(shrinker, &sc)); + seq_buf_printf(out, "requested to free: %lu\n", atomic_long_read(&shrinker->objects_requested_to_free)); + seq_buf_printf(out, "objects freed: %lu\n", nr_freed); + seq_buf_printf(out, "last scanned: %li sec ago\n", (jiffies - shrinker->last_scanned) / HZ); + seq_buf_printf(out, "last freed: %li sec ago\n", (jiffies - shrinker->last_freed) / HZ); + seq_buf_printf(out, "ns per object freed: %llu\n", nr_freed + ? div64_ul(atomic64_read(&shrinker->ns_run), nr_freed) + : 0); if (shrinker->to_text) { shrinker->to_text(out, shrinker); -- 2.45.2