Section (2) bdflush
bdflush — start, flush, or tune buffer-dirty-flush daemon
Since Linux 2.6, this system call is deprecated
and does nothing. It is likely to disappear
altogether in a future kernel release. Nowadays, the
task performed by
bdflush() starts, flushes,
or tunes the buffer-dirty-flush daemon. Only a privileged
process (one with the
CAP_SYS_ADMIN capability) may call
negative or 0, and no daemon has been started, then
bdflush() enters the daemon
code and never returns.
func is 1, some
dirty buffers are written to disk.
func is 2 or
more and is even (low bit is 0), then
address is the address of a
long word, and the tuning parameter numbered (
func−2)/2 is returned to
the caller in that address.
func is 3 or
more and is odd (low bit is 1), then
data is a long word, and the
kernel sets tuning parameter numbered (
func−3)/2 to that
The set of parameters, their values, and their valid
ranges are defined in the Linux kernel source file
negative or 0 and the daemon successfully starts,
bdflush() never returns.
Otherwise, the return value is 0 on success and −1 on
errno set to
indicate the error.
An attempt was made to enter the daemon code after another process has already entered.
addresspoints outside your accessible address space.
An attempt was made to read or write an invalid parameter number, or to write an invalid value to a parameter.
Caller does not have the
bdflush() is Linux-specific
and should not be used in programs intended to be
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Copyright (c) 1995 Michael Chastain (mecshell.portal.com), 15 April 1995.
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Modified 1997-01-31 by Eric S. Raymond <esrthyrsus.com>
Modified 2004-06-17 by Michael Kerrisk <mtk.manpagesgmail.com>