From nobody Wed Dec 17 20:40:31 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 15B1EC61D97 for ; Wed, 22 Nov 2023 23:25:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344600AbjKVXZj (ORCPT ); Wed, 22 Nov 2023 18:25:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57260 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344409AbjKVXZd (ORCPT ); Wed, 22 Nov 2023 18:25:33 -0500 Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [IPv6:2001:41d0:1004:224b::ac]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B610D110 for ; Wed, 22 Nov 2023 15:25:29 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700695528; 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=h7yT/gNa8WVPOQ61JKqXqNgHJRrqgXjHTIF9eRajh2g=; b=O6Wa1Pq7Futp9HUKsVGvdg+Z5w+n3MO/N9v0rDnM9VMU80eqJlKtDs5MCdlB/RLuq3zB75 DFQ+Bbi5//mR819xx4Wrz6FRF25hy8ONIL+PG+xyufurdr4QS6+jDEsypsEnexxM7IRVd+ TH/mv9J3tjkNle2GRCxH+jXEE/7wAlg= From: Kent Overstreet To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Kent Overstreet , Andrew Morton , Qi Zheng , Roman Gushchin Subject: [PATCH 3/7] mm: shrinker: Add new stats for .to_text() Date: Wed, 22 Nov 2023 18:25:08 -0500 Message-ID: <20231122232515.177833-4-kent.overstreet@linux.dev> In-Reply-To: <20231122232515.177833-1-kent.overstreet@linux.dev> References: <20231122232515.177833-1-kent.overstreet@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 | 5 +++++ mm/shrinker.c | 18 +++++++++++++++++- 2 files changed, 22 insertions(+), 1 deletion(-) diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 968c55474e78..497a7e8e348c 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -118,6 +118,11 @@ 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; + atomic_long_t last_freed; + atomic64_t ns_run; }; #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ =20 diff --git a/mm/shrinker.c b/mm/shrinker.c index 4976dbac4c83..acfc3f92f552 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -430,13 +430,20 @@ static unsigned long do_shrink_slab(struct shrink_con= trol *shrinkctl, total_scan >=3D freeable) { unsigned long ret; unsigned long nr_to_scan =3D min(batch_size, total_scan); + u64 start_time =3D ktime_get_ns(); + + atomic_long_add(nr_to_scan, &shrinker->objects_requested_to_free); =20 shrinkctl->nr_to_scan =3D nr_to_scan; shrinkctl->nr_scanned =3D nr_to_scan; ret =3D shrinker->scan_objects(shrinker, shrinkctl); + + atomic64_add(ktime_get_ns() - start_time, &shrinker->ns_run); if (ret =3D=3D SHRINK_STOP) break; freed +=3D ret; + atomic_long_add(ret, &shrinker->objects_freed); + atomic_long_set(&shrinker->last_freed, ret); =20 count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); total_scan -=3D shrinkctl->nr_scanned; @@ -812,9 +819,18 @@ EXPORT_SYMBOL_GPL(shrinker_free); void shrinker_to_text(struct seq_buf *out, struct shrinker *shrinker) { struct shrink_control sc =3D { .gfp_mask =3D GFP_KERNEL, }; + unsigned long nr_freed =3D atomic_long_read(&shrinker->objects_freed); =20 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", shrinker->count_objects(s= hrinker, &sc)); + seq_buf_printf(out, "requested to free: %lu", atomic_long_read(&shrinke= r->objects_requested_to_free)); + seq_buf_printf(out, "objects freed: %lu", nr_freed); + seq_buf_printf(out, "last freed: %lu", atomic_long_read(&shrinke= r->last_freed)); + seq_buf_printf(out, "ns per object freed: %llu", nr_freed + ? div64_ul(atomic64_read(&shrinker->ns_run), nr_freed) + : 0); =20 if (shrinker->to_text) { shrinker->to_text(out, shrinker); --=20 2.42.0