Re: [PATCH 2/2] fs: Support compiling out sendfile
From: josh@joshtriplett.org
Date: 2014-10-20 22:24:31
Also in:
linux-fsdevel, lkml
Possibly related (same subject, not in this thread)
- 2014-10-21 · Re: [PATCH 2/2] fs: Support compiling out sendfile · Eric Paris <eparis@redhat.com>
On Mon, Oct 20, 2014 at 11:48:37PM +0200, Pieter Smith wrote:
Many embedded systems will not need this syscall, and omitting it saves space. Add a new EXPERT config option CONFIG_SENDFILE_SYSCALL (default y) to support compiling it out.
Nice work, thanks! If there are no objections, and nobody has a tree they'd rather carry this through, I'll take the series through the tiny tree when it's ready to merge.
bloat-o-meter: add/remove: 0/4 grow/shrink: 5/0 up/down: 23/-751 (-728) function old new delta sys_pwritev 115 122 +7 sys_preadv 115 122 +7 fdput_pos 29 36 +7 sys_pwrite64 115 116 +1 sys_pread64 115 116 +1 fdput 11 - -11 sys_sendfile 122 - -122 sys_sendfile64 126 - -126 do_sendfile 492 - -492
Interesting inlining decisions by GCC here. Got a bloat-o-meter for the two-patch series, by any chance? (Also, is this with tinyconfig? In particular, with OPTIMIZE_INLINING and OPTIMIZE_FOR_SIZE?) I'm wondering if moving sendfile to a separate file made GCC put fdput out-of-line, and compiling it out reversed that again.
Signed-off-by: Pieter Smith <redacted>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
quoted hunk ↗ jump to hunk
--- fs/Makefile | 3 ++- init/Kconfig | 10 ++++++++++ kernel/sys_ni.c | 4 ++++ 3 files changed, 16 insertions(+), 1 deletion(-)diff --git a/fs/Makefile b/fs/Makefile index 1e3423f..1bbfea7 100644 --- a/fs/Makefile +++ b/fs/Makefile@@ -5,7 +5,7 @@ # Rewritten to use lists instead of if-statements. # -obj-y := open.o read_write.o sendfile.o file_table.o super.o \ +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 dcache.o inode.o \ attr.o bad_inode.o file.o filesystems.o namespace.o \@@ -38,6 +38,7 @@ obj-$(CONFIG_COMPAT_BINFMT_ELF) += compat_binfmt_elf.o obj-$(CONFIG_BINFMT_ELF_FDPIC) += binfmt_elf_fdpic.o obj-$(CONFIG_BINFMT_SOM) += binfmt_som.o obj-$(CONFIG_BINFMT_FLAT) += binfmt_flat.o +obj-$(CONFIG_SENDFILE_SYSCALL) += sendfile.o obj-$(CONFIG_FS_MBCACHE) += mbcache.o obj-$(CONFIG_FS_POSIX_ACL) += posix_acl.odiff --git a/init/Kconfig b/init/Kconfig index 782a65b..df6785c 100644 --- a/init/Kconfig +++ b/init/Kconfig@@ -1547,6 +1547,16 @@ config ADVISE_SYSCALLS applications use these syscalls, you can disable this option to save space. +config SENDFILE_SYSCALL + bool "Enable sendfile syscall" if EXPERT + default y + help + This option enables the sendfile syscall, used by applications to copy + data between file descriptors. Because sendfile performs the copying + within the kernel, it is more efficient than the combination of read + and write. If building an embedded system where no applications use + the sendfile syscall, you can disable this option to save space. +
I'm thinking of adding a submenu to group config FOO_SYSCALL options. :) I'll probably push that as part of the 3.19 merge window, as a patch on top of all of the individual tinification options.
quoted hunk ↗ jump to hunk
config PCI_QUIRKS default y bool "Enable PCI quirk workarounds" if EXPERTdiff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index d4709d4..b068de7 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c@@ -159,6 +159,10 @@ cond_syscall(sys_uselib); cond_syscall(sys_fadvise64); cond_syscall(sys_fadvise64_64); cond_syscall(sys_madvise); +cond_syscall(sys_sendfile); +cond_syscall(sys_sendfile64); +cond_syscall(compat_sys_sendfile); +cond_syscall(compat_sys_sendfile64); /* arch-specific weak syscall entries */ cond_syscall(sys_pciconfig_read);-- 1.9.1