From patchwork Tue Jun 4 06:29:18 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Granados via B4 Relay X-Patchwork-Id: 13684724 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 050DA13DDC2; Tue, 4 Jun 2024 06:29:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717482600; cv=none; b=osh6ykqNEgSQ3/RsJ+/RoJpskwKTZe92C//XZJflq97G830dgyvMgYADCRf9ejm21WehEJ4B9R52yl83lubBvm/FZPVYCKfpS4RYvDCey34p/1IJIFt7D+rZqVBdPAYXSjUSbwmrZP1v+hBvhOmYVTjEe0dNFyMgzV3k56ECOOc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717482600; c=relaxed/simple; bh=T+INzTDE9Vj+7m+fiSwp436wQ7Ya1GzvcaOJ2zGRMJM=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=ns3rvFO4mo3KYB+AF3bu/FnM7nFPxUdSUCY6APwEk3RV1oJiK1p8516ZR3R17wEQyq/4NpnvJ/3tsg1tAWGnDQZHXEuLopdsRDMiUoh17nJV5opQkGZoP0qEhXkgnsQsd8geCKBq7VAjJXVZqjbwPv1symDJ3fFD9lmMtF1C32w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TFlC/ZS3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TFlC/ZS3" Received: by smtp.kernel.org (Postfix) with ESMTPS id 889F1C2BBFC; Tue, 4 Jun 2024 06:29:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1717482599; bh=T+INzTDE9Vj+7m+fiSwp436wQ7Ya1GzvcaOJ2zGRMJM=; h=From:Subject:Date:To:Cc:Reply-To:From; b=TFlC/ZS30LUnRDy+uM1Lmyz7SgI8vziMwa1ZlXiYVsqCK5GmlTG6FI4LB3Uyei1Px 610UkX6nXJ6F1h00uRP/y6X8h3I3SLe6na/TRUuE1MgD5M9GGxs1HeMQWqEH+Los8Z hIreDOKIeG2O5eItfhXlVbS1CWzA/SRPMrgos8OhUnoFhjBfgc/E2k0T4Vx5AGsMgh W3FZBSdwpt7wSVBLuaonLJ6w2WaeY/fHTEhJfAvyd4L5CP5FL43kASovUciNSwDKke HwJoIz5T0mHyRyLC1BNzBq4QUNTOp/sjh7ANRDSVYLGTSrBIiUT3JngVuoe6AsAnhn kUEQfnFuUqZQg== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75C49C25B7E; Tue, 4 Jun 2024 06:29:59 +0000 (UTC) From: Joel Granados via B4 Relay Subject: [PATCH 0/8] sysctl: Remove sentinel check from sysctl internals Date: Tue, 04 Jun 2024 08:29:18 +0200 Message-Id: <20240604-jag-sysctl_remset-v1-0-2df7ecdba0bd@samsung.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAD60XmYC/x3M3QpAQBBA4VfRXNsau0JeRdJag5G/diSSd7e5/ C7OeUDIMwmU0QOeThbe1oAkjsCNdh1IcRcMGnWKGRo12UHJLe6YG0+L0KFS27eFy7VBNBC63VP P1/+s6vf9APoicb1jAAAA To: Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , Boqun Feng , Suren Baghdasaryan , Kent Overstreet , Andrew Morton , Luis Chamberlain , Kees Cook , Joel Granados , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5454; i=j.granados@samsung.com; h=from:subject:message-id; bh=hO67nruGWcLOvW84X+XKeZd/ahfbOIwca7ow3jpSfbc=; b=owJ4nAHtARL+kA0DAAoBupfNUreWQU8ByyZiAGZetGFfrIgm0qAxkXBF8akY86Nh4/uz1S+jh vDn/e1k+HsfMIkBswQAAQoAHRYhBK5HCVcl5jElzssnkLqXzVK3lkFPBQJmXrRhAAoJELqXzVK3 lkFPt5sMAIsGofTYusm1CrCNXBQ8FpJMaCfdZ4UfdUIi3/ZLCPDNmCDoJm9vvlGQSV5bxlrlxZB o4Gaj/xdCAe2XnUhynhzIWLcQrkHobHo0KnUZhVywFyPNtavexf6xkOKyZRina7iWbXlm9ojSPn vms2DlunREdloZHGeEp+ItfVVcMOnbsarrNh3u69QSIZ6tebBcdhGDWRqrCdXAcO/8hf5P+73FZ jL33BEgFQ/pNXlsr8kF1SI7eV1Z+rN2BO2auzybO+/hdWHbpWFySxukUegl34wkHws4yM5xC3hi BI7wPT03k+iYsntOOwVhW4pmiRPjd8RDvWgmHFCI+ts7sOoi2Hviyv5DenscGsGPEgZhh8vL7bt OiMWxQy9cv5RteMcTQI+152cOBxb4SCdHZD4JRCmKShqPxRkzJhr6fY+HfrOnKpfn8F1O9p+oOt gwpHJONzKL4EjWL+TtxY7uGwA503oA7l6bKvvd11zAWkFX4G/5Hm4vnMcH+sDtIwllg1vVr2V56 +U= X-Developer-Key: i=j.granados@samsung.com; a=openpgp; fpr=F1F8E46D30F0F6C4A45FF4465895FAAC338C6E77 X-Endpoint-Received: by B4 Relay for j.granados@samsung.com/default with auth_id=70 X-Original-From: Joel Granados Reply-To: j.granados@samsung.com From: Joel Granados What? Remove the loop stopping criteria check for ->procname == NULL, the array size calculation based on sentinels and the superfluous sentinels created within the sysctl infrastructure. None are needed as they are now solely based on ctl_table ARRAY_SIZE. Finally, sentinels that have been added in recent releases (not present for the original patchsets) were removed. Why? By removing the sysctl sentinel elements we avoid kernel bloat as ctl_table arrays get moved out of kernel/sysctl.c into their own respective subsystems. This move was started long ago to avoid merge conflicts; the sentinel removal bit is to avoid bloating the kernel by one element as arrays moved out. It includes work in /arch [1], /dirver [2], fs/ [3], kernel [4], net/ [5], mm/ [6], security/ [6], io_uring [6] and other misc directories [6]. It will reduce the overall build time size of the kernel and run time memory bloat by about ~64 bytes per declared ctl_table array (more info here [0]). Testing: * Ran sysctl selftests (./tools/testing/selftests/sysctl/sysctl.sh) * Ran this through 0-day with no errors or warnings Savings in vmlinux: A total of 64 bytes per sentinel is saved after removal. Here is the aggregated savings for all the removal patchsets ([1,2,3,4,5,6]) for the x86_64 arch (actual savings will depend on kernel conf): |------|---------|-----------|-------|-----------|--------|---------|----------------| |dir | arch[1] | driver[2] | fs[3] | kernel[4] | net[5] | misc[6] | Total(approx.) | |------|---------|-----------|-------|-----------|--------|---------|----------------| |Bytes | 192 | 2432 | 1920 | 1984 | 3976 | 963 | 11467 | |------|---------|-----------|-------|-----------|--------|---------|----------------| Savings in allocated memory: The estimated savings during boot for config [3] are 6272 bytes. See [7] for how to measure it. Comments/feedback greatly appreciated Best Joel [0] Links Related to the ctl_table sentinel removal: * Good summaries from Luis: https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/ https://lore.kernel.org/all/ZMFizKFkVxUFtSqa@bombadil.infradead.org/ * Patches adjusting sysctl register calls: https://lore.kernel.org/all/20230302204612.782387-1-mcgrof@kernel.org/ https://lore.kernel.org/all/20230302202826.776286-1-mcgrof@kernel.org/ * Discussions about expectations and approach https://lore.kernel.org/all/20230321130908.6972-1-frank.li@vivo.com https://lore.kernel.org/all/20220220060626.15885-1-tangmeng@uniontech.com [1] https://lore.kernel.org/20231002-jag-sysctl_remove_empty_elem_arch-v3-0-606da2840a7a@samsung.com [2] https://lore.kernel.org/20231002-jag-sysctl_remove_empty_elem_drivers-v2-0-02dd0d46f71e@samsung.com [3] https://lore.kernel.org/20231121-jag-sysctl_remove_empty_elem_fs-v2-0-39eab723a034@samsung.com [4] https://lore.kernel.org/20240328-jag-sysctl_remove_empty_elem_kernel-v3-0-285d273912fe@samsung.com [5] https://lore.kernel.org/20240501-jag-sysctl_remset_net-v6-0-370b702b6b4a@samsung.com [6] https://lore.kernel.org/20240328-jag-sysctl_remset_misc-v1-0-47c1463b3af2@samsung.com [7] To measure the in memory savings apply this on top of this patchset. " " and then run the following bash script in the kernel: accum=0 for n in $(dmesg | grep kzalloc | awk '{print $3}') ; do accum=$(calc "$accum + $n") done echo $accum Signed-off-by: Joel Granados --- Joel Granados (8): locking: Remove superfluous sentinel element from kern_lockdep_table mm profiling: Remove superfluous sentinel element from ctl_table sysctl: Remove check for sentinel element in ctl_table arrays sysctl: Replace nr_entries with ctl_table_size in new_links sysctl: Remove superfluous empty allocations from sysctl internals sysctl: Remove "child" sysctl code comments sysctl: Remove ctl_table sentinel code comments sysctl: Warn on an empty procname element fs/proc/proc_sysctl.c | 50 +++++++++++++++++++++--------------------------- kernel/locking/lockdep.c | 1 - lib/alloc_tag.c | 1 - net/sysctl_net.c | 11 ++--------- 4 files changed, 24 insertions(+), 39 deletions(-) --- base-commit: 1613e604df0cd359cf2a7fbd9be7a0bcfacfabd0 change-id: 20240603-jag-sysctl_remset-4afb8c723003 Best regards, diff --git i/fs/proc/proc_sysctl.c w/fs/proc/proc_sysctl.c index a6aeaa928dd2..6ca5341bcddf 100644 --- i/fs/proc/proc_sysctl.c +++ w/fs/proc/proc_sysctl.c @@ -963,6 +963,7 @@ static struct ctl_dir *new_dir(struct ctl_table_set *set, table[0].procname = new_name; table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO; init_header(&new->header, set->dir.header.root, set, node, table, 1); + printk("%ld sysctl saved mem kzalloc\n", sizeof(struct ctl_table)); return new; } @@ -1186,6 +1187,7 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_ link_name += len; link++; } + printk("%ld sysctl saved mem kzalloc\n", sizeof(struct ctl_table)); init_header(links, dir->header.root, dir->header.set, node, link_table, head->ctl_table_size); links->nreg = head->ctl_table_size;