This patchs adds the CONFIG_AIO option which allows to remove support
for asynchronous I/O operations, that are not necessarly used by
applications, particularly on embedded devices. As this is a
size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
save ~7 kilobytes of kernel code/data:
text data bss dec hex filename
1115067 119180 217088 1451335 162547 vmlinux
1108025 119048 217088 1444161 160941 vmlinux.new
-7042 -132 0 -7174 -1C06 +/-
This patch has been originally written by Matt Mackall
<[email protected]>, and is part of the Linux Tiny project.
Signed-off-by: Thomas Petazzoni <[email protected]>
Signed-off-by: Matt Mackall <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
fs/Makefile | 3 ++-
include/linux/aio.h | 9 +++++++++
init/Kconfig | 8 ++++++++
kernel/sys_ni.c | 5 +++++
kernel/sysctl.c | 2 ++
5 files changed, 26 insertions(+), 1 deletion(-)
Index: linuxdev/fs/Makefile
===================================================================
--- linuxdev.orig/fs/Makefile
+++ linuxdev/fs/Makefile
@@ -8,7 +8,7 @@
obj-y := open.o read_write.o file_table.o super.o \
char_dev.o stat.o exec.o pipe.o namei.o fcntl.o \
ioctl.o readdir.o select.o fifo.o locks.o dcache.o inode.o \
- attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \
+ attr.o bad_inode.o file.o filesystems.o namespace.o \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o drop_caches.o splice.o sync.o utimes.o \
stack.o
@@ -27,6 +27,7 @@
obj-$(CONFIG_SIGNALFD) += signalfd.o
obj-$(CONFIG_TIMERFD) += timerfd.o
obj-$(CONFIG_EVENTFD) += eventfd.o
+obj-$(CONFIG_AIO) += aio.o
obj-$(CONFIG_COMPAT) += compat.o compat_ioctl.o
nfsd-$(CONFIG_NFSD) := nfsctl.o
Index: linuxdev/include/linux/aio.h
===================================================================
--- linuxdev.orig/include/linux/aio.h
+++ linuxdev/include/linux/aio.h
@@ -204,12 +204,21 @@
/* prototypes */
extern unsigned aio_max_size;
+#ifdef CONFIG_AIO
extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
extern int aio_put_req(struct kiocb *iocb);
extern void kick_iocb(struct kiocb *iocb);
extern int aio_complete(struct kiocb *iocb, long res, long res2);
struct mm_struct;
extern void exit_aio(struct mm_struct *mm);
+#else
+static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
+static inline int aio_put_req(struct kiocb *iocb) { return 0; }
+static inline void kick_iocb(struct kiocb *iocb) { }
+static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }
+struct mm_struct;
+static inline void exit_aio(struct mm_struct *mm) { }
+#endif /* CONFIG_AIO */
#define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
Index: linuxdev/init/Kconfig
===================================================================
--- linuxdev.orig/init/Kconfig
+++ linuxdev/init/Kconfig
@@ -724,6 +724,14 @@
option replaces shmem and tmpfs with the much simpler ramfs code,
which may be appropriate on small systems without swap.
+config AIO
+ bool "Enable AIO support" if EMBEDDED
+ default y
+ help
+ This option enables POSIX asynchronous I/O which may by used
+ by some high performance threaded applications. Disabling
+ this option saves about 7k.
+
config VM_EVENT_COUNTERS
default y
bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
Index: linuxdev/kernel/sys_ni.c
===================================================================
--- linuxdev.orig/kernel/sys_ni.c
+++ linuxdev/kernel/sys_ni.c
@@ -125,6 +125,11 @@
cond_syscall(sys_vm86);
cond_syscall(compat_sys_ipc);
cond_syscall(compat_sys_sysctl);
+cond_syscall(sys_io_setup);
+cond_syscall(sys_io_destroy);
+cond_syscall(sys_io_submit);
+cond_syscall(sys_io_cancel);
+cond_syscall(sys_io_getevents);
/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read);
Index: linuxdev/kernel/sysctl.c
===================================================================
--- linuxdev.orig/kernel/sysctl.c
+++ linuxdev/kernel/sysctl.c
@@ -1290,6 +1290,7 @@
.extra1 = &zero,
.extra2 = &two,
},
+#ifdef CONFIG_AIO
{
.procname = "aio-nr",
.data = &aio_nr,
@@ -1304,6 +1305,7 @@
.mode = 0644,
.proc_handler = &proc_doulongvec_minmax,
},
+#endif /* CONFIG_AIO */
#ifdef CONFIG_INOTIFY_USER
{
.ctl_name = FS_INOTIFY,
--
Thomas Petazzoni, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
>This patchs adds the CONFIG_AIO option which allows to remove support
>for asynchronous I/O operations, that are not necessarly used by
>applications, particularly on embedded devices. As this is a
>size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
>save ~7 kilobytes of kernel code/data:
Shouldn't this also make sure not to install aio_abi.h or at least an
empty aio_abi.h?
On Thu, Jul 31, 2008 at 12:09:29PM +0200, Bernhard Fischer wrote:
> On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
> >This patchs adds the CONFIG_AIO option which allows to remove support
> >for asynchronous I/O operations, that are not necessarly used by
> >applications, particularly on embedded devices. As this is a
> >size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
> >save ~7 kilobytes of kernel code/data:
>
> Shouldn't this also make sure not to install aio_abi.h or at least an
> empty aio_abi.h?
The userspace headers are independent of any kernel configuration
(except for the architecture).
cu
Adrian
--
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
On Thu, Jul 31, 2008 at 01:12:19PM +0300, Adrian Bunk wrote:
>On Thu, Jul 31, 2008 at 12:09:29PM +0200, Bernhard Fischer wrote:
>> On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
>> >This patchs adds the CONFIG_AIO option which allows to remove support
>> >for asynchronous I/O operations, that are not necessarly used by
>> >applications, particularly on embedded devices. As this is a
>> >size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
>> >save ~7 kilobytes of kernel code/data:
>>
>> Shouldn't this also make sure not to install aio_abi.h or at least an
>> empty aio_abi.h?
>
>The userspace headers are independent of any kernel configuration
>(except for the architecture).
I beg to disagree:
internals as exposed by e.g. aio_abi.h are impl dependent. Noone except
the impl and it's users are interrested in it.
If a per package feature, independent of arch, is off, all respective
features stuff should be off for that particular installation.
I.e. if I, for subsequent installations, choose to turn on feature, the
requested feature-stuff will be installed properly. If I, OTOH, choose
to (keep to) turn off feature, then all feature-related stuff should --
and has to be and stay -- turned off.
In the particular case of the kernel exposing unwanted API extensions
that are off, all such API reminiscences should be off, thus not
installed to my staging dir at all since i explicitely asked for doing
away with all of the API.
>From a libc POV i'd agree, but from an inherently broken userspace POV
installing willingly broken stuff is just wrong and misleading, imo.
On Fri, Aug 01, 2008 at 12:42:22AM +0200, Bernhard Fischer wrote:
> On Thu, Jul 31, 2008 at 01:12:19PM +0300, Adrian Bunk wrote:
> >On Thu, Jul 31, 2008 at 12:09:29PM +0200, Bernhard Fischer wrote:
> >> On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
> >> >This patchs adds the CONFIG_AIO option which allows to remove support
> >> >for asynchronous I/O operations, that are not necessarly used by
> >> >applications, particularly on embedded devices. As this is a
> >> >size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
> >> >save ~7 kilobytes of kernel code/data:
> >>
> >> Shouldn't this also make sure not to install aio_abi.h or at least an
> >> empty aio_abi.h?
> >
> >The userspace headers are independent of any kernel configuration
> >(except for the architecture).
>
> I beg to disagree:
> internals as exposed by e.g. aio_abi.h are impl dependent. Noone except
> the impl and it's users are interrested in it.
>...
That's utter bullshit.
The contents of aio_abi.h is a kernel<->userspace ABI that mustn't ever
change. [1]
cu
Adrian
[1] there are some exceptions like adding stuff (but not in existing
structs), but basically the contents of aio_abi.h is cast in stone
--
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
Adrian Bunk wrote:
> On Fri, Aug 01, 2008 at 12:42:22AM +0200, Bernhard Fischer wrote:
> > On Thu, Jul 31, 2008 at 01:12:19PM +0300, Adrian Bunk wrote:
> > >On Thu, Jul 31, 2008 at 12:09:29PM +0200, Bernhard Fischer wrote:
> > >> On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
> > >> >This patchs adds the CONFIG_AIO option which allows to remove support
> > >> >for asynchronous I/O operations, that are not necessarly used by
> > >> >applications, particularly on embedded devices. As this is a
> > >> >size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
> > >> >save ~7 kilobytes of kernel code/data:
> > >>
> > >> Shouldn't this also make sure not to install aio_abi.h or at least an
> > >> empty aio_abi.h?
> > >
> > >The userspace headers are independent of any kernel configuration
> > >(except for the architecture).
> >
> > I beg to disagree:
> > internals as exposed by e.g. aio_abi.h are impl dependent. Noone except
> > the impl and it's users are interrested in it.
> >...
>
> That's utter bullshit.
>
> The contents of aio_abi.h is a kernel<->userspace ABI that mustn't ever
> change. [1]
Case in point:
I want to be able to compile an application for embedded Linux which
*can use* Linux-AIO, but can also run on a kernel which has Linux-AIO
removed by this patch.
I still want to compile the application with that capability, in case
it's run on another kernel with it enabled.
I shouldn't have to have a separate, special kernel with all options
enabled, just to compile applications that run on multiple kernels and
use run-time features when available.
Just like all the other kernel<->userspace interfaces, the header
files (including their presence) shouldn't depend on kernel
configuration at all.
-- Jamie
On Tue, Aug 05, 2008 at 07:26:07PM +0100, Jamie Lokier wrote:
>> > >The userspace headers are independent of any kernel configuration
>> > >(except for the architecture).
>> >
>> > I beg to disagree:
>> > internals as exposed by e.g. aio_abi.h are impl dependent. Noone except
>> > the impl and it's users are interrested in it.
>> >...
>>
>> That's utter bullshit.
>>
>> The contents of aio_abi.h is a kernel<->userspace ABI that mustn't ever
>> change. [1]
>
>Case in point:
>
>I want to be able to compile an application for embedded Linux which
>*can use* Linux-AIO, but can also run on a kernel which has Linux-AIO
>removed by this patch.
>
>I still want to compile the application with that capability, in case
>it's run on another kernel with it enabled.
>
>I shouldn't have to have a separate, special kernel with all options
>enabled, just to compile applications that run on multiple kernels and
>use run-time features when available.
>
>Just like all the other kernel<->userspace interfaces, the header
>files (including their presence) shouldn't depend on kernel
>configuration at all.
alright, makes perfect sense. I must have been playing too much with
libc recently, i guess.
thanks,