From: Sabrina Dubroca <sd@queasysnail•net>
To: j.granados@samsung•com
Cc: "David S. Miller" <davem@davemloft•net>,
Eric Dumazet <edumazet@google•com>,
Jakub Kicinski <kuba@kernel•org>, Paolo Abeni <pabeni@redhat•com>,
Alexander Aring <alex.aring@gmail•com>,
Stefan Schmidt <stefan@datenfreihafen•org>,
Miquel Raynal <miquel.raynal@bootlin•com>,
David Ahern <dsahern@kernel•org>,
Steffen Klassert <steffen.klassert@secunet•com>,
Herbert Xu <herbert@gondor•apana.org.au>,
Matthieu Baerts <matttbe@kernel•org>,
Mat Martineau <martineau@kernel•org>,
Geliang Tang <geliang@kernel•org>,
Remi Denis-Courmont <courmisch@gmail•com>,
Allison Henderson <allison.henderson@oracle•com>,
David Howells <dhowells@redhat•com>,
Marc Dionne <marc.dionne@auristor•com>,
Marcelo Ricardo Leitner <marcelo.leitner@gmail•com>,
Xin Long <lucien.xin@gmail•com>,
Wenjia Zhang <wenjia@linux•ibm.com>,
Jan Karcher <jaka@linux•ibm.com>,
"D. Wythe" <alibuda@linux•alibaba.com>,
Tony Lu <tonylu@linux•alibaba.com>,
Wen Gu <guwen@linux•alibaba.com>,
Trond Myklebust <trond.myklebust@hammerspace•com>,
Anna Schumaker <anna@kernel•org>,
Chuck Lever <chuck.lever@oracle•com>,
Jeff Layton <jlayton@kernel•org>, Neil Brown <neilb@suse•de>,
Olga Kornievskaia <kolga@netapp•com>,
Dai Ngo <Dai.Ngo@oracle•com>, Tom Talpey <tom@talpey•com>,
Jon Maloy <jmaloy@redhat•com>, Ying Xue <ying.xue@windriver•com>,
Martin Schiller <ms@dev•tdt.de>,
Pablo Neira Ayuso <pablo@netfilter•org>,
Jozsef Kadlecsik <kadlec@netfilter•org>,
Florian Westphal <fw@strlen•de>, Roopa Prabhu <roopa@nvidia•com>,
Nikolay Aleksandrov <razor@blackwall•org>,
Simon Horman <horms@verge•net.au>, Julian Anastasov <ja@ssi•bg>,
Joerg Reuter <jreuter@yaina•de>,
Luis Chamberlain <mcgrof@kernel•org>,
Kees Cook <keescook@chromium•org>,
netdev@vger•kernel.org, linux-kernel@vger•kernel.org,
dccp@vger•kernel.org, linux-wpan@vger•kernel.org,
mptcp@lists•linux.dev, linux-hams@vger•kernel.org,
linux-rdma@vger•kernel.org, rds-devel@oss•oracle.com,
linux-afs@lists•infradead.org, linux-sctp@vger•kernel.org,
linux-s390@vger•kernel.org, linux-nfs@vger•kernel.org,
tipc-discussion@lists•sourceforge.net, linux-x25@vger•kernel.org,
netfilter-devel@vger•kernel.org, coreteam@netfilter•org,
bridge@lists•linux.dev, lvs-devel@vger•kernel.org
Subject: Re: [PATCH net-next v6 0/8] sysctl: Remove sentinel elements from networking
Date: Wed, 1 May 2024 15:22:08 +0200 [thread overview]
Message-ID: <ZjJCANEjFK890VCA@hog> (raw)
In-Reply-To: <20240501-jag-sysctl_remset_net-v6-0-370b702b6b4a@samsung.com>
2024-05-01, 11:29:24 +0200, Joel Granados via B4 Relay wrote:
> From: Joel Granados <j.granados@samsung•com>
>
> What?
> These commits remove the sentinel element (last empty element) from the
> sysctl arrays of all the files under the "net/" directory that register
> a sysctl array. The merging of the preparation patches [4] to mainline
> allows us to just remove sentinel elements without changing behavior.
> This is safe because the sysctl registration code (register_sysctl() and
> friends) use the array size in addition to checking for a sentinel [1].
>
> 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 (more
> info here [5]).
>
> When are we done?
> There are 4 patchest (25 commits [2]) that are still outstanding to
> completely remove the sentinels: files under "net/" (this patchset),
> files under "kernel/" dir, misc dirs (files under mm/ security/ and
> others) and the final set that removes the unneeded check for ->procname
> == NULL.
>
> 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; I measured in
> x86_64 to give an idea of the aggregated savings. The actual savings
> will depend on individual kernel configuration.
> * bloat-o-meter
> - The "yesall" config saves 3976 bytes (bloat-o-meter output [6])
> - A reduced config [3] saves 1263 bytes (bloat-o-meter output [7])
>
> Savings in allocated memory:
> None in this set but will occur when the superfluous allocations are
> removed from proc_sysctl.c. I include it here for context. The
> estimated savings during boot for config [3] are 6272 bytes. See [8]
> for how to measure it.
>
> Comments/feedback greatly appreciated
>
> Changes in v6:
> - Rebased onto net-next/main.
> - Besides re-running my cocci scripts, I ran a new find script [9].
> Found 0 hits in net/
> - Moved "i" variable declaraction out of for() in sysctl_core_net_init
> - Removed forgotten sentinel in mpls_table
> - Removed CONFIG_AX25_DAMA_SLAVE guard from net/ax25/ax25_ds_timer.c. It
> is not needed because that file is compiled only when
> CONFIG_AX25_DAMA_SLAVE is set.
> - When traversing smc_table, stop on ARRAY_SIZE instead of ARRAY_SIZE-1.
> - Link to v5: https://lore.kernel.org/r/20240426-jag-sysctl_remset_net-v5-0-e3b12f6111a6@samsung.com
I pointed out a few tiny details in the ax25 patch but either way, the
series looks good to me. Thanks!
Series:
Reviewed-by: Sabrina Dubroca <sd@queasysnail•net>
Note that you could have kept the ack/reviewed-by on patch 4 since it
was not modified. Jeff and Chuck, your reviews got lost in the repost.
--
Sabrina
next prev parent reply other threads:[~2024-05-01 13:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-01 9:29 [PATCH net-next v6 0/8] sysctl: Remove sentinel elements from networking Joel Granados via B4 Relay
2024-05-01 9:29 ` [PATCH net-next v6 1/8] net: Remove the now superfluous sentinel elements from ctl_table array Joel Granados via B4 Relay
2024-05-03 12:40 ` patchwork-bot+netdevbpf
2024-05-01 9:29 ` [PATCH net-next v6 2/8] net: ipv{6,4}: " Joel Granados via B4 Relay
2024-05-01 9:29 ` [PATCH net-next v6 3/8] net: rds: " Joel Granados via B4 Relay
2024-05-03 2:27 ` Allison Henderson
2024-05-01 9:29 ` [PATCH net-next v6 4/8] net: sunrpc: " Joel Granados via B4 Relay
2024-05-01 9:29 ` [PATCH net-next v6 5/8] net: Remove ctl_table sentinel elements from several networking subsystems Joel Granados via B4 Relay
2024-05-01 9:29 ` [PATCH net-next v6 6/8] netfilter: Remove the now superfluous sentinel elements from ctl_table array Joel Granados via B4 Relay
2024-05-01 9:29 ` [PATCH net-next v6 7/8] appletalk: " Joel Granados via B4 Relay
2024-05-01 9:29 ` [PATCH net-next v6 8/8] ax.25: x.25: " Joel Granados via B4 Relay
2024-05-01 13:15 ` Sabrina Dubroca
2024-05-03 12:18 ` Joel Granados
2024-05-03 15:23 ` Dan Carpenter
2024-05-07 8:02 ` Joel Granados
2024-05-01 13:22 ` Sabrina Dubroca [this message]
2024-05-03 12:20 ` [PATCH net-next v6 0/8] sysctl: Remove sentinel elements from networking Joel Granados
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