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.)
Given the requirements of running a file server in the kernel, I'd
expect CONFIG_NFSD to end up with several more selects of optional
functionality in the future. It seems rather likely that the average
embedded system will be compiling out NFS. :)
Also, this patch series compiles out splice and sendfile, including
several *users* of sendpage; it doesn't compile out the sendpage
support/infrastructure itself.
- Josh Triplett
From: Pieter Smith <hidden> Date: 2014-11-23 20:30:40
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:
quoted
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.
Given the requirements of running a file server in the kernel, I'd
expect CONFIG_NFSD to end up with several more selects of optional
functionality in the future. It seems rather likely that the average
embedded system will be compiling out NFS. :)
Also, this patch series compiles out splice and sendfile, including
several *users* of sendpage; it doesn't compile out the sendpage
support/infrastructure itself.
- Josh Triplett
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:
quoted
On Sun, Nov 23, 2014 at 01:46:23PM -0500, David Miller wrote:
quoted
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.
That said, given that it seems exceedingly unlikely that anyone would
use the in-kernel nfsd on a system trying to minimize kernel size, it
still seems cleaner to just "select SPLICE_SYSCALL" from NFSD in
Kconfig. That avoids making any changes at all to the nfsd source in
this patch series.
- Josh Triplett
From: Jeff Layton <hidden> Date: 2014-11-24 00:28:10
On Sun, 23 Nov 2014 15:36:37 -0800
Josh Triplett [off-list ref] wrote:
On Sun, Nov 23, 2014 at 09:30:40PM +0100, Pieter Smith wrote:
quoted
On Sun, Nov 23, 2014 at 11:43:26AM -0800, Josh Triplett wrote:
quoted
On Sun, Nov 23, 2014 at 01:46:23PM -0500, David Miller wrote:
quoted
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.
I'd probably prefer the above, actually. We have to keep supporting
non-splice enabled fs' for the forseeable future, so we may as well
allow people to run nfsd in such configurations. It could even be
useful for testing the non-splice-enabled codepaths.
That said, given that it seems exceedingly unlikely that anyone would
use the in-kernel nfsd on a system trying to minimize kernel size, it
still seems cleaner to just "select SPLICE_SYSCALL" from NFSD in
Kconfig. That avoids making any changes at all to the nfsd source in
this patch series.
On Mon, Nov 24, 2014 at 12:36 AM, Josh Triplett [off-list ref] wrote:
On Sun, Nov 23, 2014 at 09:30:40PM +0100, Pieter Smith wrote:
quoted
On Sun, Nov 23, 2014 at 11:43:26AM -0800, Josh Triplett wrote:
quoted
On Sun, Nov 23, 2014 at 01:46:23PM -0500, David Miller wrote:
quoted
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-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.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