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author | Kay Sievers <kay.sievers@vrfy.org> | 2009-03-09 14:18:52 +0100 |
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committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-03-24 16:38:26 -0700 |
commit | 4995f8ef9d3aac72745e12419d7fbaa8d01b1d81 (patch) | |
tree | 32b86d8b5f5ccba8f367d3e911ba3d1e19d73729 /arch/arm/mach-at91/board-sam9263ek.c | |
parent | ce21c7bcd796fc4f45d48781b7e85f493cc55ee5 (diff) | |
download | linux-4995f8ef9d3aac72745e12419d7fbaa8d01b1d81.tar.gz linux-4995f8ef9d3aac72745e12419d7fbaa8d01b1d81.tar.bz2 linux-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 'arch/arm/mach-at91/board-sam9263ek.c')
0 files changed, 0 insertions, 0 deletions