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| author |   Kay Sievers <kay.sievers@vrfy.org> | 2009-03-09 14:18:52 +0100 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@suse.de> | 2009-03-24 16:38:26 -0700 |
| commit | 4995f8ef9d3aac72745e12419d7fbaa8d01b1d81 (patch) | |
| tree | 32b86d8b5f5ccba8f367d3e911ba3d1e19d73729 /drivers/char/vc_screen.c | |
| parent | driver core: fix passing platform_data (diff) | |
| download | linux-dev-4995f8ef9d3aac72745e12419d7fbaa8d01b1d81.tar.xz linux-dev-4995f8ef9d3aac72745e12419d7fbaa8d01b1d81.zip | |
vcs: hook sysfs devices into object lifetime instead of "binding"
During bootup performance tracing I noticed many occurrences of
vca* device creation and removal, leading to the usual userspace
uevent processing, which are, in this case, rather pointless.
A simple test showing the kernel timing (not including all the
work userspace has to do), gives us these numbers:
$ time for i in `seq 1000`; do echo a > /dev/tty2; done
real 0m1.142s
user 0m0.015s
sys 0m0.540s
If we move the hook for the vcs* driver core devices from the
tty "binding" to the vc allocation/deallocation, which is what
the vcs* devices represent, we get the following numbers:
$ time for i in `seq 1000`; do echo a > /dev/tty2; done
real 0m0.152s
user 0m0.030s
sys 0m0.072s
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/char/vc_screen.c')
| -rw-r--r-- | drivers/char/vc_screen.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/drivers/char/vc_screen.c b/drivers/char/vc_screen.c index 4f3b3f95fc42..d94d25c12aa8 100644 --- a/drivers/char/vc_screen.c +++ b/drivers/char/vc_screen.c @@ -479,18 +479,18 @@ static const struct file_operations vcs_fops = { static struct class *vc_class; -void vcs_make_sysfs(struct tty_struct *tty) +void vcs_make_sysfs(int index) { - device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 1), NULL, - "vcs%u", tty->index + 1); - device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 129), NULL, - "vcsa%u", tty->index + 1); + device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL, + "vcs%u", index + 1); + device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL, + "vcsa%u", index + 1); } -void vcs_remove_sysfs(struct tty_struct *tty) +void vcs_remove_sysfs(int index) { - device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 1)); - device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 129)); + device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1)); + device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129)); } int __init vcs_init(void) |