From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793868258; b=rZwS1z6J4ZMqu2RsSyi8EC8rC4g3AT4QpJF4jDCDq2C9PzJZubUIXGWyOKLgK08NGtH7 KFkqZ+3Z/vQFNgAxcDyZs34FAo8Lgf+5wfJDamqdGIiw6sDOJ0NwzKGDt06JgEPZGMc4M dXmKUCZ460+OuQR2fTT71cCt1mcsZ8Rt7tuxhZJQjbN0AvjXhpBZ/jrYy/rPtfhhEkvLY +5A2XS3mChWROFFGfI0hQscKTDq56xbzki75rohJQ4BooY6JOvV8/tzS0dC5eJbTQiZEn pNAzWEXLBxCDgTJKVq+eNdG7RcrEfEkDdzo0DIUvdr7sDySMtRplOh+uo9VQTzQf2/w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793868258; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer; bh=ZaNkuK+CuZCH16Zfn9adKcMMnVfFDERJiwr1XCFoM7M=; b=4Z6Q9vQf1T8oniO8MYTZ14ERcwxHbBunjasLcizOYAy6eVx7v0EEpdFDnkfbB/KNvsJM OjAk+4NY+/IIoUNYeOgY5bXU31xKpcPqrsnxczJVrWIZd2/4B7s1sYudHp88pqfDgNMYW CjXMH2NVdYkYZs5Aj3FCz9ftLAE/KKrqkDkOxkYsvu7RLS7xBhRmG8ALUmzjdt4nKsUe5 ulZW5epz3f1mImnPdCXHy1ITsck9rDPtN0EpXFeCo77H0zxS264uGwgN81xY0vAJvJo4N iRalNdpriWaMeHJkPldevrE2a3xd1O0dSIQYBkbDcVAGkRObUuBsyAK48zhKSL9Dzyg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Xl6rJmUN; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1ED15606A326 for ; Thu, 5 Nov 2026 08:44:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Xl6rJmUN Received: by smtp.kernel.org (Postfix) with ESMTPSA id 709831F00A15; Thu, 5 Nov 2026 08:44:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793868257; bh=ZaNkuK+CuZCH16Zfn9adKcMMnVfFDERJiwr1XCFoM7M=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=Xl6rJmUN/DWrJon99nZtxTbfk5UDamIX8Eq/y4HE94KYkSeXgDheIx+53+ZQXd1Mu 0k/BcEHNgJQsE7TMa0C3mD1aclFY0HQgwxmwGUdYvkPy5Y5QXplmW0GjNqokKIbklS 9iz0MpLl7bh6vPvauR9kFF/es4F1pI94mOdmOXv7NqAZ/GtvlVvyfM5Bn1RYdz2mjy omCm9bRJ67oFRb4w6BgXx9sow/DiQOP3Yt/y+fmktLRG05HRq/QLdnXVmrOpx7iPiZ G3Fuw4HJgbR2Lf/LgqGjojP4OkERYm/vSAr8k8gXDTmWnvSaeeC3oqHV4mq/T8zR1z YLOG9Herkid2w== From: "Vlastimil Babka (SUSE)" Date: Thu, 05 Nov 2026 09:43:55 +0100 Subject: [PATCH v3 06/10] mm, slab: make SLUB_TINY handling dynamic for sizing decisions X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261105-slub_tiny_rework-v3-6-0484ce59eabb@kernel.org> References: <20261105-slub_tiny_rework-v3-0-0484ce59eabb@kernel.org> In-Reply-To: <20261105-slub_tiny_rework-v3-0-0484ce59eabb@kernel.org> To: Harry Yoo , Andrey Ryabinin Cc: Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Geert Uytterhoeven , Conor Dooley , Damien Le Moal , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , kasan-dev@googlegroups.com, "Vlastimil Babka (SUSE)" X-Mailer: b4 0.16.0 Enabling CONFIG_SLUB_TINY results in the caches' min partial slabs threshold to be zero, thus every slab where all objects become free is freed immediately. It also sets the default slab_max_order to 1, with the goal of reducing the potential of internal slab fragmentation. Rework both of these decisions to be based on the newly introduced slab_tiny_enabled flag instead of #ifdefs. It's still possible to override the reduced slab_max_order with the boot parameter, as before. Signed-off-by: Vlastimil Babka (SUSE) --- mm/slub.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index a3ee1bdf0eb3..be4e1f193295 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -272,7 +272,6 @@ void *fixup_red_left(struct kmem_cache *s, void *p) /* Enable to log cmpxchg failures */ #undef SLUB_DEBUG_CMPXCHG -#ifndef CONFIG_SLUB_TINY /* * Minimum number of partial slabs. These will be left on the partial * lists even if they are empty. kmem_cache_shrink may reclaim them. @@ -285,10 +284,6 @@ void *fixup_red_left(struct kmem_cache *s, void *p) * sort the partial list by the number of objects in use. */ #define MAX_PARTIAL 10 -#else -#define MIN_PARTIAL 0 -#define MAX_PARTIAL 0 -#endif #define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \ SLAB_POISON | SLAB_STORE_USER) @@ -7706,8 +7701,7 @@ EXPORT_SYMBOL(kmem_cache_alloc_bulk_noprof); * take the list_lock. */ static unsigned int slab_min_order; -static unsigned int slab_max_order = - IS_ENABLED(CONFIG_SLUB_TINY) ? 1 : PAGE_ALLOC_COSTLY_ORDER; +static unsigned int slab_max_order = PAGE_ALLOC_COSTLY_ORDER; static unsigned int slab_min_objects; /* @@ -8027,7 +8021,7 @@ static unsigned int calculate_sheaf_capacity(struct kmem_cache *s, size_t size; - if (IS_ENABLED(CONFIG_SLUB_TINY) || s->flags & SLAB_DEBUG_FLAGS) + if (slab_tiny_enabled || s->flags & SLAB_DEBUG_FLAGS) return 0; /* @@ -8763,6 +8757,9 @@ void __init kmem_cache_init(void) slab_obj_ext_has_codetag_init(); + if (slab_tiny_enabled) + slab_max_order = 1; + if (slab_max_order_param <= MAX_PAGE_ORDER) slab_max_order = slab_max_order_param; @@ -8886,6 +8883,8 @@ int do_kmem_cache_create(struct kmem_cache *s, const char *name, */ s->min_partial = min_t(unsigned long, MAX_PARTIAL, ilog2(s->size) / 2); s->min_partial = max_t(unsigned long, MIN_PARTIAL, s->min_partial); + if (slab_tiny_enabled) + s->min_partial = 0; s->cpu_sheaves = alloc_percpu(struct slub_percpu_sheaves); if (!s->cpu_sheaves) { -- 2.56.0