Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753041AbaKXIiZ (ORCPT ); Mon, 24 Nov 2014 03:38:25 -0500 Received: from mail-lb0-f174.google.com ([209.85.217.174]:38532 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752532AbaKXIiW (ORCPT ); Mon, 24 Nov 2014 03:38:22 -0500 MIME-Version: 1.0 In-Reply-To: <20141123233637.GC12456@thin> References: <1416752468-1626-1-git-send-email-pieter@boesman.nl> <20141123.134623.2061031332250984539.davem@davemloft.net> <20141123194326.GB8517@thin> <20141123203040.GB26749@smipidev> <20141123233637.GC12456@thin> Date: Mon, 24 Nov 2014 09:38:20 +0100 X-Google-Sender-Auth: peioOhpX1wWVlyXatAAORO_v8CI Message-ID: Subject: Re: [PATCH 0/6] kernel tinification: optionally compile out splice family of syscalls (splice, vmsplice, tee and sendfile) From: Geert Uytterhoeven To: Josh Triplett Cc: Pieter Smith , David Miller , alexander.h.duyck@intel.com, Al Viro , Alexei Starovoitov , Andrew Morton , beber@meleeweb.net, catalina.mocanu@gmail.com, Daniel Borkmann , Eric Dumazet , "Eric W. Biederman" , Fabian Frederick , fuse-devel@lists.sourceforge.net, Hugh Dickins , iulia.manda21@gmail.com, Jan Beulich , bfields@fieldses.org, jlayton@poochiereds.net, linux-api@vger.kernel.org, Linux FS Devel , "linux-kernel@vger.kernel.org" , "Luis R. Rodriguez" , Matt Turner , Mel Gorman , "Michael S. Tsirkin" , Miklos Szeredi , "netdev@vger.kernel.org" , Oleg Nesterov , Paul.Durrant@citrix.com, Paul McKenney , Peter Foley , Thomas Graf , Tom Herbert , willemb@google.com, xiaoguangrong@linux.vnet.ibm.com, zhenglong.cai@cs2c.com.cn Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 24, 2014 at 12:36 AM, Josh Triplett wrote: > On Sun, Nov 23, 2014 at 09:30:40PM +0100, Pieter Smith wrote: >> On Sun, Nov 23, 2014 at 11:43:26AM -0800, Josh Triplett wrote: >> > On Sun, Nov 23, 2014 at 01:46:23PM -0500, David Miller wrote: >> > > Truly removing sendfile/sendpage means that you can't even compile NFS >> > > into the tree. >> > >> > If you mean the in-kernel nfsd (CONFIG_NFSD), that already has a large >> > stack of "select" and "depends on", both directly and indirectly; adding >> > a "select SPLICE_SYSCALL" to it seems fine. (That select does need >> > adding, though. Pieter, you need to test-compile more than just >> > tinyconfig and defconfig. Try an allyesconfig with *just* splice turned >> > off, and make sure that compiles.) >> >> Did exacly that. Took forever on my hardware, but no problems. > > Ah, I see. Looking more closely at nfsd, it looks like it already has a > code path for filesystems that don't do splice. I think, rather than > making nfsd select SPLICE_SYSCALL, that it would suffice to change the > "rqstp->rq_splice_ok = true;" in svc_process_common (net/sunrpc/svc.c) > to: > > rqstp->rq_splice_ok = IS_ENABLED(CONFIG_SPLICE_SYSCALL); > > Then nfsd should simply *always* fall back to its non-splice support. Hence I suggest adding to the nfsd help text: While nfsd works without SPLICE_SYSCALL, you may want to enable SPLICE_SYSCALL for <...> (performance?) reasons. (Hmm, does Kconfig need a "suggests", cfr. Debian package dependencies?) Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/