From patchwork Mon Oct 2 08:55:17 2023 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: 13405715 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id ACA9EE784B2 for ; Mon, 2 Oct 2023 08:53:27 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B611510E237; Mon, 2 Oct 2023 08:53:22 +0000 (UTC) Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by gabe.freedesktop.org (Postfix) with ESMTPS id 88A3210E237; Mon, 2 Oct 2023 08:53:17 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id 91F4EB80DDC; Mon, 2 Oct 2023 08:53:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPS id D7198C433C8; Mon, 2 Oct 2023 08:53:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696236794; bh=IZog35uNq8vGRsNKIfEniN68FE7olg9OC5FvS2SzfCc=; h=From:Subject:Date:To:Cc:Reply-To:From; b=hufwGK8eMTwpAZzY5tjjCcSrUlENx2R+GHGSL/MRXkOFuLxlRDrpxb7L8+UmzAAMY 3kyrLlmdif7UJUhx8unTHOW05aoTQTW9PQR/22MMlDEvRzoawpbBHEOwCPKVSGi9hX 0wD8UynDxT9GxWBuVaKGJb1hefuvPbZhQSQ6hYcimLZgnX/osYq003o8rF1prmfvhi LtYeFa0hAvwXxBPpAp66rx2duVRL7Q2j6tUSgp66GHPQLnypVAF+y5Z1tfYpYJ5k6j /t6wPv+O/vLovGDIQr1Jl99KdgEs2bk9jJSQfzwBDj1gwVb8p3QcZWt/rbklVbQMGh 6tqQLbbnXv/NQ== 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 B437FE784A5; Mon, 2 Oct 2023 08:53:14 +0000 (UTC) From: Joel Granados via B4 Relay Date: Mon, 02 Oct 2023 10:55:17 +0200 Message-Id: <20231002-jag-sysctl_remove_empty_elem_drivers-v2-0-02dd0d46f71e@samsung.com> MIME-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAHWFGmUC/43NSw6DIBSF4a0YxqVB7EM66j4aQwhe9DYihmtJj XHvpSadd/ifwflWRhARiN2KlUVISBjGHPJQMNubsQOObW4mhayEklf+NB2nhew86Ag+JNDgp3n RMIDXbcQEkbgT1UldpBFtbVm+miI4fO/Mo8ndI80hLruayu/6A+r/gFRyweGsSimcNcqpOxlPr 7E72uBZs23bB7xaV5/aAAAA To: Luis Chamberlain , willy@infradead.org, josh@joshtriplett.org, Kees Cook , Phillip Potter , Clemens Ladisch , Arnd Bergmann , Greg Kroah-Hartman , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Jiri Slaby , "James E.J. Bottomley" , "Martin K. Petersen" , Doug Gilbert , Sudip Mukherjee , Jason Gunthorpe , Leon Romanovsky , Corey Minyard , Theodore Ts'o , "Jason A. Donenfeld" , David Ahern , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Robin Holt , Steve Wahl , Russ Weight , "Rafael J. Wysocki" , Song Liu , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Daniel Vetter X-Mailer: b4 0.13-dev-86aa5 X-Developer-Signature: v=1; a=openpgp-sha256; l=12365; i=j.granados@samsung.com; h=from:subject:message-id; bh=odYjDIhyzOtO5Q0U203ntyluw37NErA2/ZkJretAk7g=; b=owEB7QES/pANAwAKAbqXzVK3lkFPAcsmYgBlGoV7hvNwCIGX3CH1hN+xorNhoD5xKwuTuTXzC Hr03QRHgz2JAbMEAAEKAB0WIQSuRwlXJeYxJc7LJ5C6l81St5ZBTwUCZRqFewAKCRC6l81St5ZB T9oDC/wKVdRDpAFA8LsfwGfmauawotop1selvIUUiWvIA6Ydbya0ucL7Chq71gwhtiD6XFgnEAm MYfELkOZ3OHpp+ERmRTsKo2NcA+1/OHMfAADX3brGP5OWKzGXVhkR9GYDAYD1XPo6ShiUZIT+Cu fIFO+s/Wg5tgnVjs4yE44jXRFPsbH3pwnqxFGbAbX26GI+GTPo+jjtUL0a+WcbJy9Mpxpu2+bDO TZHVixlLPOqq3YBxSBPOYQ+IYTra4MO9MYTdEdvQhfSGZgVBw+fdrG0/5caISy38c3S91WaLLFV pXyRzsol2P/FUrSXxdgKSkD6vBheUaywFVgt6cstLp4+/yStMgYYYcknx5Mlf4LOwuebaFLKAau pP1GDHZXYoR6xKI2UghYY1DX7mGloY0U16rrWh7f2hSAvTBsMHyzN1GS5nrtecfUmMpDNvqcDx6 WIPfHqbSx6RcqFTDisa1KnzCA91No7YAHYQrpOwTMzCuakkbopEGnu34ba88MRprtuL3M= 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 Subject: [Intel-gfx] [PATCH v2 00/15] sysctl: Remove sentinel elements from drivers X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: j.granados@samsung.com Cc: Joel Granados , linux-hyperv@vger.kernel.org, linux-scsi@vger.kernel.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-raid@vger.kernel.org, linux-serial@vger.kernel.org, xen-devel@lists.xenproject.org, openipmi-developer@lists.sourceforge.net, linuxppc-dev@lists.ozlabs.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" From: Joel Granados What? These commits remove the sentinel element (last empty element) from the sysctl arrays of all the files under the "drivers/" directory that use a sysctl array for registration. The merging of the preparation patches (in https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/) to mainline allows us to just remove sentinel elements without changing behavior (more info here [1]). These commits are part of a bigger set (here https://github.com/Joelgranados/linux/tree/tag/sysctl_remove_empty_elem_V4) that remove the ctl_table sentinel. Make the review process easier by chunking the commits into manageable pieces. Each chunk can be reviewed separately without noise from parallel sets. Now that the architecture chunk has been mostly reviewed [6], we send the "drivers/" directory. Once this one is done, it will be follwed by "fs/*", "kernel/*", "net/*" and miscellaneous. The final set will remove the unneeded check for ->procname == NULL. 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 came after Mathew Wilcox suggested it to avoid bloating the kernel by one element as arrays moved out. This patchset will reduce the overall build time size of the kernel and run time memory bloat by about ~64 bytes per declared ctl_table array. I have consolidated some links that shed light on the history of this effort [2]. Testing: * Ran sysctl selftests (./tools/testing/selftests/sysctl/sysctl.sh) * Ran this through 0-day with no errors or warnings Size saving after removing all sentinels: These are the bytes that we save after removing all the sentinels (this plus all the other chunks). I included them to get an idea of how much memory we are talking about. * bloat-o-meter: - The "yesall" configuration results save 9158 bytes https://lore.kernel.org/all/20230621091000.424843-1-j.granados@samsung.com/ - The "tiny" config + CONFIG_SYSCTL save 1215 bytes https://lore.kernel.org/all/20230809105006.1198165-1-j.granados@samsung.com/ * memory usage: In memory savings are measured to be 7296 bytes. (here is how to measure [3]) Size saving after this patchset: * bloat-o-meter - The "yesall" config saves 2432 bytes [4] - The "tiny" config saves 64 bytes [5] * memory usage: In this case there were no bytes saved because I do not have any of the drivers in the patch. To measure it comment the printk in `new_dir` and uncomment the if conditional in `new_links` [3]. Reviewed-by: David Ahern Reviewed-by: Steve Wahl --- Changes in v2: - Left the dangling comma in the ctl_table arrays. - Link to v1: https://lore.kernel.org/r/20230928-jag-sysctl_remove_empty_elem_drivers-v1-0-e59120fca9f9@samsung.com Comments/feedback greatly appreciated Best Joel [1] We are able to remove a sentinel table without behavioral change by introducing a table_size argument in the same place where procname is checked for NULL. The idea is for it to keep stopping when it hits ->procname == NULL, while the sentinel is still present. And when the sentinel is removed, it will stop on the table_size. You can go to (https://lore.kernel.org/all/20230809105006.1198165-1-j.granados@samsung.com/) for more information. [2] Links Related to the ctl_table sentinel removal: * Good summary from Luis sent with the "pull request" for the preparation patches. https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/ * Another very good summary from Luis. https://lore.kernel.org/all/ZMFizKFkVxUFtSqa@bombadil.infradead.org/ * This is a patch set that replaces register_sysctl_table with register_sysctl https://lore.kernel.org/all/20230302204612.782387-1-mcgrof@kernel.org/ * Patch set to deprecate register_sysctl_paths() https://lore.kernel.org/all/20230302202826.776286-1-mcgrof@kernel.org/ * Here there is an explicit expectation for the removal of the sentinel element. https://lore.kernel.org/all/20230321130908.6972-1-frank.li@vivo.com * The "ARRAY_SIZE" approach was mentioned (proposed?) in this thread https://lore.kernel.org/all/20220220060626.15885-1-tangmeng@uniontech.com [3] 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 echo $n accum=$(calc "$accum + $n") done echo $accum [4] add/remove: 0/0 grow/shrink: 0/21 up/down: 0/-2432 (-2432) Function old new delta xpc_sys_xpc_hb 192 128 -64 xpc_sys_xpc 128 64 -64 vrf_table 128 64 -64 ucma_ctl_table 128 64 -64 tty_table 192 128 -64 sg_sysctls 128 64 -64 scsi_table 128 64 -64 random_table 448 384 -64 raid_table 192 128 -64 oa_table 192 128 -64 mac_hid_files 256 192 -64 iwcm_ctl_table 128 64 -64 ipmi_table 128 64 -64 hv_ctl_table 128 64 -64 hpet_table 128 64 -64 firmware_config_table 192 128 -64 cdrom_table 448 384 -64 balloon_table 128 64 -64 parport_sysctl_template 912 720 -192 parport_default_sysctl_table 584 136 -448 parport_device_sysctl_template 776 136 -640 Total: Before=429940038, After=429937606, chg -0.00% [5] add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-64 (-64) Function old new delta random_table 448 384 -64 Total: Before=1885527, After=1885463, chg -0.00% [6] https://lore.kernel.org/all/20230913-jag-sysctl_remove_empty_elem_arch-v2-0-d1bd13a29bae@samsung.com/ Signed-off-by: Joel Granados To: Luis Chamberlain To: willy@infradead.org To: josh@joshtriplett.org To: Kees Cook To: Phillip Potter To: Clemens Ladisch To: Arnd Bergmann To: Greg Kroah-Hartman To: Juergen Gross To: Stefano Stabellini To: Oleksandr Tyshchenko To: Jiri Slaby To: "James E.J. Bottomley" To: "Martin K. Petersen" To: Doug Gilbert To: Sudip Mukherjee To: Jason Gunthorpe To: Leon Romanovsky To: Corey Minyard To: Theodore Ts'o To: "Jason A. Donenfeld" To: David Ahern To: "David S. Miller" To: Eric Dumazet To: Jakub Kicinski To: Paolo Abeni To: Robin Holt To: Steve Wahl To: Russ Weight To: "Rafael J. Wysocki" To: Song Liu To: "K. Y. Srinivasan" To: Haiyang Zhang To: Wei Liu To: Dexuan Cui To: Jani Nikula To: Joonas Lahtinen To: Rodrigo Vivi To: Tvrtko Ursulin To: David Airlie To: Daniel Vetter Cc: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xenproject.org Cc: linux-serial@vger.kernel.org Cc: linux-scsi@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-rdma@vger.kernel.org Cc: openipmi-developer@lists.sourceforge.net Cc: netdev@vger.kernel.org Cc: linux-raid@vger.kernel.org Cc: linux-hyperv@vger.kernel.org Cc: intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org --- --- Joel Granados (15): cdrom: Remove now superfluous sentinel element from ctl_table array hpet: Remove now superfluous sentinel element from ctl_table array xen: Remove now superfluous sentinel element from ctl_table array tty: Remove now superfluous sentinel element from ctl_table array scsi: Remove now superfluous sentinel element from ctl_table array parport: Remove the now superfluous sentinel element from ctl_table array macintosh: Remove the now superfluous sentinel element from ctl_table array infiniband: Remove the now superfluous sentinel element from ctl_table array char-misc: Remove the now superfluous sentinel element from ctl_table array vrf: Remove the now superfluous sentinel element from ctl_table array sgi-xp: Remove the now superfluous sentinel element from ctl_table array fw loader: Remove the now superfluous sentinel element from ctl_table array raid: Remove now superfluous sentinel element from ctl_table array Drivers: hv: Remove now superfluous sentinel element from ctl_table array intel drm: Remove now superfluous sentinel element from ctl_table array drivers/base/firmware_loader/fallback_table.c | 1 - drivers/cdrom/cdrom.c | 1 - drivers/char/hpet.c | 1 - drivers/char/ipmi/ipmi_poweroff.c | 1 - drivers/char/random.c | 1 - drivers/gpu/drm/i915/i915_perf.c | 1 - drivers/hv/hv_common.c | 1 - drivers/infiniband/core/iwcm.c | 1 - drivers/infiniband/core/ucma.c | 1 - drivers/macintosh/mac_hid.c | 1 - drivers/md/md.c | 1 - drivers/misc/sgi-xp/xpc_main.c | 2 -- drivers/net/vrf.c | 1 - drivers/parport/procfs.c | 28 +++++++++++---------------- drivers/scsi/scsi_sysctl.c | 1 - drivers/scsi/sg.c | 1 - drivers/tty/tty_io.c | 1 - drivers/xen/balloon.c | 1 - 18 files changed, 11 insertions(+), 35 deletions(-) --- base-commit: 0e945134b680040b8613e962f586d91b6d40292d change-id: 20230927-jag-sysctl_remove_empty_elem_drivers-f034962a0d8c Best regards, diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index c88854df0b62..e0073a627bac 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -976,6 +976,8 @@ 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); + // Counts additional sentinel used for each new dir. + printk("%ld sysctl saved mem kzalloc \n", sizeof(struct ctl_table)); return new; } @@ -1199,6 +1201,9 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_ link_name += len; link++; } + // Counts additional sentinel used for each new registration + //if ((head->ctl_table + head->ctl_table_size)->procname) + 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 = nr_entries;